1 /* 2 * Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 package java.lang; 26 27 import java.io.BufferedInputStream; 28 import java.io.BufferedOutputStream; 29 import java.io.Console; 30 import java.io.FileDescriptor; 31 import java.io.FileInputStream; 32 import java.io.FileOutputStream; 33 import java.io.IOException; 34 import java.io.InputStream; 35 import java.io.PrintStream; 36 import java.io.UnsupportedEncodingException; 37 import java.lang.annotation.Annotation; 38 import java.lang.invoke.MethodHandle; 39 import java.lang.invoke.MethodType; 40 import java.lang.module.ModuleDescriptor; 41 import java.lang.reflect.Constructor; 42 import java.lang.reflect.Executable; 43 import java.lang.reflect.Method; 44 import java.lang.reflect.Modifier; 45 import java.net.URI; 46 import java.nio.charset.CharacterCodingException; 47 import java.security.AccessControlContext; 48 import java.security.ProtectionDomain; 49 import java.security.AccessController; 50 import java.security.PrivilegedAction; 51 import java.nio.channels.Channel; 52 import java.nio.channels.spi.SelectorProvider; 53 import java.nio.charset.Charset; 54 import java.util.Iterator; 55 import java.util.List; 56 import java.util.Map; 57 import java.util.Objects; 58 import java.util.Properties; 59 import java.util.PropertyPermission; 60 import java.util.ResourceBundle; 61 import java.util.function.Supplier; 62 import java.util.concurrent.ConcurrentHashMap; 63 import java.util.stream.Stream; 64 65 import jdk.internal.util.StaticProperty; 66 import jdk.internal.module.ModuleBootstrap; 67 import jdk.internal.module.ServicesCatalog; 68 import jdk.internal.reflect.CallerSensitive; 69 import jdk.internal.reflect.Reflection; 70 import jdk.internal.HotSpotIntrinsicCandidate; 71 import jdk.internal.access.JavaLangAccess; 72 import jdk.internal.access.SharedSecrets; 73 import jdk.internal.misc.VM; 74 import jdk.internal.logger.LoggerFinderLoader; 75 import jdk.internal.logger.LazyLoggers; 76 import jdk.internal.logger.LocalizedLoggerWrapper; 77 import jdk.internal.util.SystemProps; 78 import jdk.internal.vm.annotation.Stable; 79 import sun.nio.fs.DefaultFileSystemProvider; 80 import sun.reflect.annotation.AnnotationType; 81 import sun.nio.ch.Interruptible; 82 import sun.security.util.SecurityConstants; 83 84 /** 85 * The {@code System} class contains several useful class fields 86 * and methods. It cannot be instantiated. 87 * 88 * Among the facilities provided by the {@code System} class 89 * are standard input, standard output, and error output streams; 90 * access to externally defined properties and environment 91 * variables; a means of loading files and libraries; and a utility 92 * method for quickly copying a portion of an array. 93 * 94 * @since 1.0 95 */ 96 public final class System { 97 /* Register the natives via the static initializer. 98 * 99 * The VM will invoke the initPhase1 method to complete the initialization 100 * of this class separate from <clinit>. 101 */ 102 private static native void registerNatives(); 103 static { 104 registerNatives(); 105 } 106 107 /** Don't let anyone instantiate this class */ 108 private System() { 109 } 110 111 /** 112 * The "standard" input stream. This stream is already 113 * open and ready to supply input data. Typically this stream 114 * corresponds to keyboard input or another input source specified by 115 * the host environment or user. 116 */ 117 public static final InputStream in = null; 118 119 /** 120 * The "standard" output stream. This stream is already 121 * open and ready to accept output data. Typically this stream 122 * corresponds to display output or another output destination 123 * specified by the host environment or user. 124 * <p> 125 * For simple stand-alone Java applications, a typical way to write 126 * a line of output data is: 127 * <blockquote><pre> 128 * System.out.println(data) 129 * </pre></blockquote> 130 * <p> 131 * See the {@code println} methods in class {@code PrintStream}. 132 * 133 * @see java.io.PrintStream#println() 134 * @see java.io.PrintStream#println(boolean) 135 * @see java.io.PrintStream#println(char) 136 * @see java.io.PrintStream#println(char[]) 137 * @see java.io.PrintStream#println(double) 138 * @see java.io.PrintStream#println(float) 139 * @see java.io.PrintStream#println(int) 140 * @see java.io.PrintStream#println(long) 141 * @see java.io.PrintStream#println(java.lang.Object) 142 * @see java.io.PrintStream#println(java.lang.String) 143 */ 144 public static final PrintStream out = null; 145 146 /** 147 * The "standard" error output stream. This stream is already 148 * open and ready to accept output data. 149 * <p> 150 * Typically this stream corresponds to display output or another 151 * output destination specified by the host environment or user. By 152 * convention, this output stream is used to display error messages 153 * or other information that should come to the immediate attention 154 * of a user even if the principal output stream, the value of the 155 * variable {@code out}, has been redirected to a file or other 156 * destination that is typically not continuously monitored. 157 */ 158 public static final PrintStream err = null; 159 160 // indicates if a security manager is possible 161 private static final int NEVER = 1; 162 private static final int MAYBE = 2; 163 private static @Stable int allowSecurityManager; 164 165 // current security manager 166 private static volatile SecurityManager security; // read by VM 167 168 // return true if a security manager is allowed 169 private static boolean allowSecurityManager() { 170 return (allowSecurityManager != NEVER); 171 } 172 173 /** 174 * Reassigns the "standard" input stream. 175 * 176 * First, if there is a security manager, its {@code checkPermission} 177 * method is called with a {@code RuntimePermission("setIO")} permission 178 * to see if it's ok to reassign the "standard" input stream. 179 * 180 * @param in the new standard input stream. 181 * 182 * @throws SecurityException 183 * if a security manager exists and its 184 * {@code checkPermission} method doesn't allow 185 * reassigning of the standard input stream. 186 * 187 * @see SecurityManager#checkPermission 188 * @see java.lang.RuntimePermission 189 * 190 * @since 1.1 191 */ 192 public static void setIn(InputStream in) { 193 checkIO(); 194 setIn0(in); 195 } 196 197 /** 198 * Reassigns the "standard" output stream. 199 * 200 * First, if there is a security manager, its {@code checkPermission} 201 * method is called with a {@code RuntimePermission("setIO")} permission 202 * to see if it's ok to reassign the "standard" output stream. 203 * 204 * @param out the new standard output stream 205 * 206 * @throws SecurityException 207 * if a security manager exists and its 208 * {@code checkPermission} method doesn't allow 209 * reassigning of the standard output stream. 210 * 211 * @see SecurityManager#checkPermission 212 * @see java.lang.RuntimePermission 213 * 214 * @since 1.1 215 */ 216 public static void setOut(PrintStream out) { 217 checkIO(); 218 setOut0(out); 219 } 220 221 /** 222 * Reassigns the "standard" error output stream. 223 * 224 * First, if there is a security manager, its {@code checkPermission} 225 * method is called with a {@code RuntimePermission("setIO")} permission 226 * to see if it's ok to reassign the "standard" error output stream. 227 * 228 * @param err the new standard error output stream. 229 * 230 * @throws SecurityException 231 * if a security manager exists and its 232 * {@code checkPermission} method doesn't allow 233 * reassigning of the standard error output stream. 234 * 235 * @see SecurityManager#checkPermission 236 * @see java.lang.RuntimePermission 237 * 238 * @since 1.1 239 */ 240 public static void setErr(PrintStream err) { 241 checkIO(); 242 setErr0(err); 243 } 244 245 private static volatile Console cons; 246 247 /** 248 * Returns the unique {@link java.io.Console Console} object associated 249 * with the current Java virtual machine, if any. 250 * 251 * @return The system console, if any, otherwise {@code null}. 252 * 253 * @since 1.6 254 */ 255 public static Console console() { 256 Console c; 257 if ((c = cons) == null) { 258 synchronized (System.class) { 259 if ((c = cons) == null) { 260 cons = c = SharedSecrets.getJavaIOAccess().console(); 261 } 262 } 263 } 264 return c; 265 } 266 267 /** 268 * Returns the channel inherited from the entity that created this 269 * Java virtual machine. 270 * 271 * This method returns the channel obtained by invoking the 272 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel 273 * inheritedChannel} method of the system-wide default 274 * {@link java.nio.channels.spi.SelectorProvider} object. 275 * 276 * <p> In addition to the network-oriented channels described in 277 * {@link java.nio.channels.spi.SelectorProvider#inheritedChannel 278 * inheritedChannel}, this method may return other kinds of 279 * channels in the future. 280 * 281 * @return The inherited channel, if any, otherwise {@code null}. 282 * 283 * @throws IOException 284 * If an I/O error occurs 285 * 286 * @throws SecurityException 287 * If a security manager is present and it does not 288 * permit access to the channel. 289 * 290 * @since 1.5 291 */ 292 public static Channel inheritedChannel() throws IOException { 293 return SelectorProvider.provider().inheritedChannel(); 294 } 295 296 private static void checkIO() { 297 SecurityManager sm = getSecurityManager(); 298 if (sm != null) { 299 sm.checkPermission(new RuntimePermission("setIO")); 300 } 301 } 302 303 private static native void setIn0(InputStream in); 304 private static native void setOut0(PrintStream out); 305 private static native void setErr0(PrintStream err); 306 307 /** 308 * Sets the system-wide security manager. 309 * 310 * If there is a security manager already installed, this method first 311 * calls the security manager's {@code checkPermission} method 312 * with a {@code RuntimePermission("setSecurityManager")} 313 * permission to ensure it's ok to replace the existing 314 * security manager. 315 * This may result in throwing a {@code SecurityException}. 316 * 317 * <p> Otherwise, the argument is established as the current 318 * security manager. If the argument is {@code null} and no 319 * security manager has been established, then no action is taken and 320 * the method simply returns. 321 * 322 * @implNote In the JDK implementation, if the Java virtual machine is 323 * started with the system property {@code java.security.manager} set to 324 * the special token "{@code disallow}" then the {@code setSecurityManager} 325 * method cannot be used to set a security manager. 326 * 327 * @param sm the security manager or {@code null} 328 * @throws SecurityException 329 * if the security manager has already been set and its {@code 330 * checkPermission} method doesn't allow it to be replaced 331 * @throws UnsupportedOperationException 332 * if {@code sm} is non-null and a security manager is not allowed 333 * to be set dynamically 334 * @see #getSecurityManager 335 * @see SecurityManager#checkPermission 336 * @see java.lang.RuntimePermission 337 */ 338 public static void setSecurityManager(SecurityManager sm) { 339 if (allowSecurityManager()) { 340 if (security == null) { 341 // ensure image reader is initialized 342 Object.class.getResource("java/lang/ANY"); 343 // ensure the default file system is initialized 344 DefaultFileSystemProvider.theFileSystem(); 345 } 346 if (sm != null) { 347 try { 348 // pre-populates the SecurityManager.packageAccess cache 349 // to avoid recursive permission checking issues with custom 350 // SecurityManager implementations 351 sm.checkPackageAccess("java.lang"); 352 } catch (Exception e) { 353 // no-op 354 } 355 } 356 setSecurityManager0(sm); 357 } else { 358 // security manager not allowed 359 if (sm != null) { 360 throw new UnsupportedOperationException( 361 "Runtime configured to disallow security manager"); 362 } 363 } 364 } 365 366 private static synchronized 367 void setSecurityManager0(final SecurityManager s) { 368 SecurityManager sm = getSecurityManager(); 369 if (sm != null) { 370 // ask the currently installed security manager if we 371 // can replace it. 372 sm.checkPermission(new RuntimePermission("setSecurityManager")); 373 } 374 375 if ((s != null) && (s.getClass().getClassLoader() != null)) { 376 // New security manager class is not on bootstrap classpath. 377 // Force policy to get initialized before we install the new 378 // security manager, in order to prevent infinite loops when 379 // trying to initialize the policy (which usually involves 380 // accessing some security and/or system properties, which in turn 381 // calls the installed security manager's checkPermission method 382 // which will loop infinitely if there is a non-system class 383 // (in this case: the new security manager class) on the stack). 384 AccessController.doPrivileged(new PrivilegedAction<>() { 385 public Object run() { 386 s.getClass().getProtectionDomain().implies 387 (SecurityConstants.ALL_PERMISSION); 388 return null; 389 } 390 }); 391 } 392 393 security = s; 394 } 395 396 /** 397 * Gets the system-wide security manager. 398 * 399 * @return if a security manager has already been established for the 400 * current application, then that security manager is returned; 401 * otherwise, {@code null} is returned. 402 * @see #setSecurityManager 403 */ 404 public static SecurityManager getSecurityManager() { 405 if (allowSecurityManager()) { 406 return security; 407 } else { 408 return null; 409 } 410 } 411 412 /** 413 * Returns the current time in milliseconds. Note that 414 * while the unit of time of the return value is a millisecond, 415 * the granularity of the value depends on the underlying 416 * operating system and may be larger. For example, many 417 * operating systems measure time in units of tens of 418 * milliseconds. 419 * 420 * <p> See the description of the class {@code Date} for 421 * a discussion of slight discrepancies that may arise between 422 * "computer time" and coordinated universal time (UTC). 423 * 424 * @return the difference, measured in milliseconds, between 425 * the current time and midnight, January 1, 1970 UTC. 426 * @see java.util.Date 427 */ 428 @HotSpotIntrinsicCandidate 429 public static native long currentTimeMillis(); 430 431 /** 432 * Returns the current value of the running Java Virtual Machine's 433 * high-resolution time source, in nanoseconds. 434 * 435 * This method can only be used to measure elapsed time and is 436 * not related to any other notion of system or wall-clock time. 437 * The value returned represents nanoseconds since some fixed but 438 * arbitrary <i>origin</i> time (perhaps in the future, so values 439 * may be negative). The same origin is used by all invocations of 440 * this method in an instance of a Java virtual machine; other 441 * virtual machine instances are likely to use a different origin. 442 * 443 * <p>This method provides nanosecond precision, but not necessarily 444 * nanosecond resolution (that is, how frequently the value changes) 445 * - no guarantees are made except that the resolution is at least as 446 * good as that of {@link #currentTimeMillis()}. 447 * 448 * <p>Differences in successive calls that span greater than 449 * approximately 292 years (2<sup>63</sup> nanoseconds) will not 450 * correctly compute elapsed time due to numerical overflow. 451 * 452 * <p>The values returned by this method become meaningful only when 453 * the difference between two such values, obtained within the same 454 * instance of a Java virtual machine, is computed. 455 * 456 * <p>For example, to measure how long some code takes to execute: 457 * <pre> {@code 458 * long startTime = System.nanoTime(); 459 * // ... the code being measured ... 460 * long elapsedNanos = System.nanoTime() - startTime;}</pre> 461 * 462 * <p>To compare elapsed time against a timeout, use <pre> {@code 463 * if (System.nanoTime() - startTime >= timeoutNanos) ...}</pre> 464 * instead of <pre> {@code 465 * if (System.nanoTime() >= startTime + timeoutNanos) ...}</pre> 466 * because of the possibility of numerical overflow. 467 * 468 * @return the current value of the running Java Virtual Machine's 469 * high-resolution time source, in nanoseconds 470 * @since 1.5 471 */ 472 @HotSpotIntrinsicCandidate 473 public static native long nanoTime(); 474 475 /** 476 * Copies an array from the specified source array, beginning at the 477 * specified position, to the specified position of the destination array. 478 * A subsequence of array components are copied from the source 479 * array referenced by {@code src} to the destination array 480 * referenced by {@code dest}. The number of components copied is 481 * equal to the {@code length} argument. The components at 482 * positions {@code srcPos} through 483 * {@code srcPos+length-1} in the source array are copied into 484 * positions {@code destPos} through 485 * {@code destPos+length-1}, respectively, of the destination 486 * array. 487 * <p> 488 * If the {@code src} and {@code dest} arguments refer to the 489 * same array object, then the copying is performed as if the 490 * components at positions {@code srcPos} through 491 * {@code srcPos+length-1} were first copied to a temporary 492 * array with {@code length} components and then the contents of 493 * the temporary array were copied into positions 494 * {@code destPos} through {@code destPos+length-1} of the 495 * destination array. 496 * <p> 497 * If {@code dest} is {@code null}, then a 498 * {@code NullPointerException} is thrown. 499 * <p> 500 * If {@code src} is {@code null}, then a 501 * {@code NullPointerException} is thrown and the destination 502 * array is not modified. 503 * <p> 504 * Otherwise, if any of the following is true, an 505 * {@code ArrayStoreException} is thrown and the destination is 506 * not modified: 507 * <ul> 508 * <li>The {@code src} argument refers to an object that is not an 509 * array. 510 * <li>The {@code dest} argument refers to an object that is not an 511 * array. 512 * <li>The {@code src} argument and {@code dest} argument refer 513 * to arrays whose component types are different primitive types. 514 * <li>The {@code src} argument refers to an array with a primitive 515 * component type and the {@code dest} argument refers to an array 516 * with a reference component type. 517 * <li>The {@code src} argument refers to an array with a reference 518 * component type and the {@code dest} argument refers to an array 519 * with a primitive component type. 520 * </ul> 521 * <p> 522 * Otherwise, if any of the following is true, an 523 * {@code IndexOutOfBoundsException} is 524 * thrown and the destination is not modified: 525 * <ul> 526 * <li>The {@code srcPos} argument is negative. 527 * <li>The {@code destPos} argument is negative. 528 * <li>The {@code length} argument is negative. 529 * <li>{@code srcPos+length} is greater than 530 * {@code src.length}, the length of the source array. 531 * <li>{@code destPos+length} is greater than 532 * {@code dest.length}, the length of the destination array. 533 * </ul> 534 * <p> 535 * Otherwise, if any actual component of the source array from 536 * position {@code srcPos} through 537 * {@code srcPos+length-1} cannot be converted to the component 538 * type of the destination array by assignment conversion, an 539 * {@code ArrayStoreException} is thrown. In this case, let 540 * <b><i>k</i></b> be the smallest nonnegative integer less than 541 * length such that {@code src[srcPos+}<i>k</i>{@code ]} 542 * cannot be converted to the component type of the destination 543 * array; when the exception is thrown, source array components from 544 * positions {@code srcPos} through 545 * {@code srcPos+}<i>k</i>{@code -1} 546 * will already have been copied to destination array positions 547 * {@code destPos} through 548 * {@code destPos+}<i>k</I>{@code -1} and no other 549 * positions of the destination array will have been modified. 550 * (Because of the restrictions already itemized, this 551 * paragraph effectively applies only to the situation where both 552 * arrays have component types that are reference types.) 553 * 554 * @param src the source array. 555 * @param srcPos starting position in the source array. 556 * @param dest the destination array. 557 * @param destPos starting position in the destination data. 558 * @param length the number of array elements to be copied. 559 * @throws IndexOutOfBoundsException if copying would cause 560 * access of data outside array bounds. 561 * @throws ArrayStoreException if an element in the {@code src} 562 * array could not be stored into the {@code dest} array 563 * because of a type mismatch. 564 * @throws NullPointerException if either {@code src} or 565 * {@code dest} is {@code null}. 566 */ 567 @HotSpotIntrinsicCandidate 568 public static native void arraycopy(Object src, int srcPos, 569 Object dest, int destPos, 570 int length); 571 572 /** 573 * Returns the same hash code for the given object as 574 * would be returned by the default method hashCode(), 575 * whether or not the given object's class overrides 576 * hashCode(). 577 * The hash code for the null reference is zero. 578 * 579 * @param x object for which the hashCode is to be calculated 580 * @return the hashCode 581 * @since 1.1 582 * @see Object#hashCode 583 * @see java.util.Objects#hashCode(Object) 584 */ 585 @HotSpotIntrinsicCandidate 586 public static native int identityHashCode(Object x); 587 588 /** 589 * System properties. The following properties are guaranteed to be defined: 590 * <dl> 591 * <dt>java.version <dd>Java version number 592 * <dt>java.version.date <dd>Java version date 593 * <dt>java.vendor <dd>Java vendor specific string 594 * <dt>java.vendor.url <dd>Java vendor URL 595 * <dt>java.vendor.version <dd>Java vendor version 596 * <dt>java.home <dd>Java installation directory 597 * <dt>java.class.version <dd>Java class version number 598 * <dt>java.class.path <dd>Java classpath 599 * <dt>os.name <dd>Operating System Name 600 * <dt>os.arch <dd>Operating System Architecture 601 * <dt>os.version <dd>Operating System Version 602 * <dt>file.separator <dd>File separator ("/" on Unix) 603 * <dt>path.separator <dd>Path separator (":" on Unix) 604 * <dt>line.separator <dd>Line separator ("\n" on Unix) 605 * <dt>user.name <dd>User account name 606 * <dt>user.home <dd>User home directory 607 * <dt>user.dir <dd>User's current working directory 608 * </dl> 609 */ 610 611 private static Properties props; 612 613 /** 614 * Determines the current system properties. 615 * 616 * First, if there is a security manager, its 617 * {@code checkPropertiesAccess} method is called with no 618 * arguments. This may result in a security exception. 619 * <p> 620 * The current set of system properties for use by the 621 * {@link #getProperty(String)} method is returned as a 622 * {@code Properties} object. If there is no current set of 623 * system properties, a set of system properties is first created and 624 * initialized. This set of system properties includes a value 625 * for each of the following keys unless the description of the associated 626 * value indicates that the value is optional. 627 * <table class="striped" style="text-align:left"> 628 * <caption style="display:none">Shows property keys and associated values</caption> 629 * <thead> 630 * <tr><th scope="col">Key</th> 631 * <th scope="col">Description of Associated Value</th></tr> 632 * </thead> 633 * <tbody> 634 * <tr><th scope="row">{@systemProperty java.version}</th> 635 * <td>Java Runtime Environment version, which may be interpreted 636 * as a {@link Runtime.Version}</td></tr> 637 * <tr><th scope="row">{@systemProperty java.version.date}</th> 638 * <td>Java Runtime Environment version date, in ISO-8601 YYYY-MM-DD 639 * format, which may be interpreted as a {@link 640 * java.time.LocalDate}</td></tr> 641 * <tr><th scope="row">{@systemProperty java.vendor}</th> 642 * <td>Java Runtime Environment vendor</td></tr> 643 * <tr><th scope="row">{@systemProperty java.vendor.url}</th> 644 * <td>Java vendor URL</td></tr> 645 * <tr><th scope="row">{@systemProperty java.vendor.version}</th> 646 * <td>Java vendor version <em>(optional)</em> </td></tr> 647 * <tr><th scope="row">{@systemProperty java.home}</th> 648 * <td>Java installation directory</td></tr> 649 * <tr><th scope="row">{@systemProperty java.vm.specification.version}</th> 650 * <td>Java Virtual Machine specification version, whose value is the 651 * {@linkplain Runtime.Version#feature feature} element of the 652 * {@linkplain Runtime#version() runtime version}</td></tr> 653 * <tr><th scope="row">{@systemProperty java.vm.specification.vendor}</th> 654 * <td>Java Virtual Machine specification vendor</td></tr> 655 * <tr><th scope="row">{@systemProperty java.vm.specification.name}</th> 656 * <td>Java Virtual Machine specification name</td></tr> 657 * <tr><th scope="row">{@systemProperty java.vm.version}</th> 658 * <td>Java Virtual Machine implementation version which may be 659 * interpreted as a {@link Runtime.Version}</td></tr> 660 * <tr><th scope="row">{@systemProperty java.vm.vendor}</th> 661 * <td>Java Virtual Machine implementation vendor</td></tr> 662 * <tr><th scope="row">{@systemProperty java.vm.name}</th> 663 * <td>Java Virtual Machine implementation name</td></tr> 664 * <tr><th scope="row">{@systemProperty java.specification.version}</th> 665 * <td>Java Runtime Environment specification version, whose value is 666 * the {@linkplain Runtime.Version#feature feature} element of the 667 * {@linkplain Runtime#version() runtime version}</td></tr> 668 * <tr><th scope="row">{@systemProperty java.specification.vendor}</th> 669 * <td>Java Runtime Environment specification vendor</td></tr> 670 * <tr><th scope="row">{@systemProperty java.specification.name}</th> 671 * <td>Java Runtime Environment specification name</td></tr> 672 * <tr><th scope="row">{@systemProperty java.class.version}</th> 673 * <td>Java class format version number</td></tr> 674 * <tr><th scope="row">{@systemProperty java.class.path}</th> 675 * <td>Java class path (refer to 676 * {@link ClassLoader#getSystemClassLoader()} for details)</td></tr> 677 * <tr><th scope="row">{@systemProperty java.library.path}</th> 678 * <td>List of paths to search when loading libraries</td></tr> 679 * <tr><th scope="row">{@systemProperty java.io.tmpdir}</th> 680 * <td>Default temp file path</td></tr> 681 * <tr><th scope="row">{@systemProperty java.compiler}</th> 682 * <td>Name of JIT compiler to use</td></tr> 683 * <tr><th scope="row">{@systemProperty os.name}</th> 684 * <td>Operating system name</td></tr> 685 * <tr><th scope="row">{@systemProperty os.arch}</th> 686 * <td>Operating system architecture</td></tr> 687 * <tr><th scope="row">{@systemProperty os.version}</th> 688 * <td>Operating system version</td></tr> 689 * <tr><th scope="row">{@systemProperty file.separator}</th> 690 * <td>File separator ("/" on UNIX)</td></tr> 691 * <tr><th scope="row">{@systemProperty path.separator}</th> 692 * <td>Path separator (":" on UNIX)</td></tr> 693 * <tr><th scope="row">{@systemProperty line.separator}</th> 694 * <td>Line separator ("\n" on UNIX)</td></tr> 695 * <tr><th scope="row">{@systemProperty user.name}</th> 696 * <td>User's account name</td></tr> 697 * <tr><th scope="row">{@systemProperty user.home}</th> 698 * <td>User's home directory</td></tr> 699 * <tr><th scope="row">{@systemProperty user.dir}</th> 700 * <td>User's current working directory</td></tr> 701 * </tbody> 702 * </table> 703 * <p> 704 * Multiple paths in a system property value are separated by the path 705 * separator character of the platform. 706 * <p> 707 * Note that even if the security manager does not permit the 708 * {@code getProperties} operation, it may choose to permit the 709 * {@link #getProperty(String)} operation. 710 * 711 * @apiNote 712 * <strong>Changing a standard system property may have unpredictable results 713 * unless otherwise specified.</strong> 714 * Property values may be cached during initialization or on first use. 715 * Setting a standard property after initialization using {@link #getProperties()}, 716 * {@link #setProperties(Properties)}, {@link #setProperty(String, String)}, or 717 * {@link #clearProperty(String)} may not have the desired effect. 718 * 719 * @implNote 720 * In addition to the standard system properties, the system 721 * properties may include the following keys: 722 * <table class="striped"> 723 * <caption style="display:none">Shows property keys and associated values</caption> 724 * <thead> 725 * <tr><th scope="col">Key</th> 726 * <th scope="col">Description of Associated Value</th></tr> 727 * </thead> 728 * <tbody> 729 * <tr><th scope="row">{@systemProperty jdk.module.path}</th> 730 * <td>The application module path</td></tr> 731 * <tr><th scope="row">{@systemProperty jdk.module.upgrade.path}</th> 732 * <td>The upgrade module path</td></tr> 733 * <tr><th scope="row">{@systemProperty jdk.module.main}</th> 734 * <td>The module name of the initial/main module</td></tr> 735 * <tr><th scope="row">{@systemProperty jdk.module.main.class}</th> 736 * <td>The main class name of the initial module</td></tr> 737 * </tbody> 738 * </table> 739 * 740 * @return the system properties 741 * @throws SecurityException if a security manager exists and its 742 * {@code checkPropertiesAccess} method doesn't allow access 743 * to the system properties. 744 * @see #setProperties 745 * @see java.lang.SecurityException 746 * @see java.lang.SecurityManager#checkPropertiesAccess() 747 * @see java.util.Properties 748 */ 749 public static Properties getProperties() { 750 SecurityManager sm = getSecurityManager(); 751 if (sm != null) { 752 sm.checkPropertiesAccess(); 753 } 754 755 return props; 756 } 757 758 /** 759 * Returns the system-dependent line separator string. It always 760 * returns the same value - the initial value of the {@linkplain 761 * #getProperty(String) system property} {@code line.separator}. 762 * 763 * <p>On UNIX systems, it returns {@code "\n"}; on Microsoft 764 * Windows systems it returns {@code "\r\n"}. 765 * 766 * @return the system-dependent line separator string 767 * @since 1.7 768 */ 769 public static String lineSeparator() { 770 return lineSeparator; 771 } 772 773 private static String lineSeparator; 774 775 /** 776 * Sets the system properties to the {@code Properties} argument. 777 * 778 * First, if there is a security manager, its 779 * {@code checkPropertiesAccess} method is called with no 780 * arguments. This may result in a security exception. 781 * <p> 782 * The argument becomes the current set of system properties for use 783 * by the {@link #getProperty(String)} method. If the argument is 784 * {@code null}, then the current set of system properties is 785 * forgotten. 786 * 787 * @apiNote 788 * <strong>Changing a standard system property may have unpredictable results 789 * unless otherwise specified</strong>. 790 * See {@linkplain #getProperties getProperties} for details. 791 * 792 * @param props the new system properties. 793 * @throws SecurityException if a security manager exists and its 794 * {@code checkPropertiesAccess} method doesn't allow access 795 * to the system properties. 796 * @see #getProperties 797 * @see java.util.Properties 798 * @see java.lang.SecurityException 799 * @see java.lang.SecurityManager#checkPropertiesAccess() 800 */ 801 public static void setProperties(Properties props) { 802 SecurityManager sm = getSecurityManager(); 803 if (sm != null) { 804 sm.checkPropertiesAccess(); 805 } 806 807 if (props == null) { 808 Map<String, String> tempProps = SystemProps.initProperties(); 809 VersionProps.init(tempProps); 810 props = createProperties(tempProps); 811 } 812 System.props = props; 813 } 814 815 /** 816 * Gets the system property indicated by the specified key. 817 * 818 * First, if there is a security manager, its 819 * {@code checkPropertyAccess} method is called with the key as 820 * its argument. This may result in a SecurityException. 821 * <p> 822 * If there is no current set of system properties, a set of system 823 * properties is first created and initialized in the same manner as 824 * for the {@code getProperties} method. 825 * 826 * @apiNote 827 * <strong>Changing a standard system property may have unpredictable results 828 * unless otherwise specified</strong>. 829 * See {@linkplain #getProperties getProperties} for details. 830 * 831 * @param key the name of the system property. 832 * @return the string value of the system property, 833 * or {@code null} if there is no property with that key. 834 * 835 * @throws SecurityException if a security manager exists and its 836 * {@code checkPropertyAccess} method doesn't allow 837 * access to the specified system property. 838 * @throws NullPointerException if {@code key} is {@code null}. 839 * @throws IllegalArgumentException if {@code key} is empty. 840 * @see #setProperty 841 * @see java.lang.SecurityException 842 * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String) 843 * @see java.lang.System#getProperties() 844 */ 845 public static String getProperty(String key) { 846 checkKey(key); 847 SecurityManager sm = getSecurityManager(); 848 if (sm != null) { 849 sm.checkPropertyAccess(key); 850 } 851 852 return props.getProperty(key); 853 } 854 855 /** 856 * Gets the system property indicated by the specified key. 857 * 858 * First, if there is a security manager, its 859 * {@code checkPropertyAccess} method is called with the 860 * {@code key} as its argument. 861 * <p> 862 * If there is no current set of system properties, a set of system 863 * properties is first created and initialized in the same manner as 864 * for the {@code getProperties} method. 865 * 866 * @param key the name of the system property. 867 * @param def a default value. 868 * @return the string value of the system property, 869 * or the default value if there is no property with that key. 870 * 871 * @throws SecurityException if a security manager exists and its 872 * {@code checkPropertyAccess} method doesn't allow 873 * access to the specified system property. 874 * @throws NullPointerException if {@code key} is {@code null}. 875 * @throws IllegalArgumentException if {@code key} is empty. 876 * @see #setProperty 877 * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String) 878 * @see java.lang.System#getProperties() 879 */ 880 public static String getProperty(String key, String def) { 881 checkKey(key); 882 SecurityManager sm = getSecurityManager(); 883 if (sm != null) { 884 sm.checkPropertyAccess(key); 885 } 886 887 return props.getProperty(key, def); 888 } 889 890 /** 891 * Sets the system property indicated by the specified key. 892 * 893 * First, if a security manager exists, its 894 * {@code SecurityManager.checkPermission} method 895 * is called with a {@code PropertyPermission(key, "write")} 896 * permission. This may result in a SecurityException being thrown. 897 * If no exception is thrown, the specified property is set to the given 898 * value. 899 * 900 * @apiNote 901 * <strong>Changing a standard system property may have unpredictable results 902 * unless otherwise specified</strong>. 903 * See {@linkplain #getProperties getProperties} for details. 904 * 905 * @param key the name of the system property. 906 * @param value the value of the system property. 907 * @return the previous value of the system property, 908 * or {@code null} if it did not have one. 909 * 910 * @throws SecurityException if a security manager exists and its 911 * {@code checkPermission} method doesn't allow 912 * setting of the specified property. 913 * @throws NullPointerException if {@code key} or 914 * {@code value} is {@code null}. 915 * @throws IllegalArgumentException if {@code key} is empty. 916 * @see #getProperty 917 * @see java.lang.System#getProperty(java.lang.String) 918 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 919 * @see java.util.PropertyPermission 920 * @see SecurityManager#checkPermission 921 * @since 1.2 922 */ 923 public static String setProperty(String key, String value) { 924 checkKey(key); 925 SecurityManager sm = getSecurityManager(); 926 if (sm != null) { 927 sm.checkPermission(new PropertyPermission(key, 928 SecurityConstants.PROPERTY_WRITE_ACTION)); 929 } 930 931 return (String) props.setProperty(key, value); 932 } 933 934 /** 935 * Removes the system property indicated by the specified key. 936 * 937 * First, if a security manager exists, its 938 * {@code SecurityManager.checkPermission} method 939 * is called with a {@code PropertyPermission(key, "write")} 940 * permission. This may result in a SecurityException being thrown. 941 * If no exception is thrown, the specified property is removed. 942 * 943 * @apiNote 944 * <strong>Changing a standard system property may have unpredictable results 945 * unless otherwise specified</strong>. 946 * See {@linkplain #getProperties getProperties} method for details. 947 * 948 * @param key the name of the system property to be removed. 949 * @return the previous string value of the system property, 950 * or {@code null} if there was no property with that key. 951 * 952 * @throws SecurityException if a security manager exists and its 953 * {@code checkPropertyAccess} method doesn't allow 954 * access to the specified system property. 955 * @throws NullPointerException if {@code key} is {@code null}. 956 * @throws IllegalArgumentException if {@code key} is empty. 957 * @see #getProperty 958 * @see #setProperty 959 * @see java.util.Properties 960 * @see java.lang.SecurityException 961 * @see java.lang.SecurityManager#checkPropertiesAccess() 962 * @since 1.5 963 */ 964 public static String clearProperty(String key) { 965 checkKey(key); 966 SecurityManager sm = getSecurityManager(); 967 if (sm != null) { 968 sm.checkPermission(new PropertyPermission(key, "write")); 969 } 970 971 return (String) props.remove(key); 972 } 973 974 private static void checkKey(String key) { 975 if (key == null) { 976 throw new NullPointerException("key can't be null"); 977 } 978 if (key.isEmpty()) { 979 throw new IllegalArgumentException("key can't be empty"); 980 } 981 } 982 983 /** 984 * Gets the value of the specified environment variable. An 985 * environment variable is a system-dependent external named 986 * value. 987 * 988 * <p>If a security manager exists, its 989 * {@link SecurityManager#checkPermission checkPermission} 990 * method is called with a 991 * {@link RuntimePermission RuntimePermission("getenv."+name)} 992 * permission. This may result in a {@link SecurityException} 993 * being thrown. If no exception is thrown the value of the 994 * variable {@code name} is returned. 995 * 996 * <p><a id="EnvironmentVSSystemProperties"><i>System 997 * properties</i> and <i>environment variables</i></a> are both 998 * conceptually mappings between names and values. Both 999 * mechanisms can be used to pass user-defined information to a 1000 * Java process. Environment variables have a more global effect, 1001 * because they are visible to all descendants of the process 1002 * which defines them, not just the immediate Java subprocess. 1003 * They can have subtly different semantics, such as case 1004 * insensitivity, on different operating systems. For these 1005 * reasons, environment variables are more likely to have 1006 * unintended side effects. It is best to use system properties 1007 * where possible. Environment variables should be used when a 1008 * global effect is desired, or when an external system interface 1009 * requires an environment variable (such as {@code PATH}). 1010 * 1011 * <p>On UNIX systems the alphabetic case of {@code name} is 1012 * typically significant, while on Microsoft Windows systems it is 1013 * typically not. For example, the expression 1014 * {@code System.getenv("FOO").equals(System.getenv("foo"))} 1015 * is likely to be true on Microsoft Windows. 1016 * 1017 * @param name the name of the environment variable 1018 * @return the string value of the variable, or {@code null} 1019 * if the variable is not defined in the system environment 1020 * @throws NullPointerException if {@code name} is {@code null} 1021 * @throws SecurityException 1022 * if a security manager exists and its 1023 * {@link SecurityManager#checkPermission checkPermission} 1024 * method doesn't allow access to the environment variable 1025 * {@code name} 1026 * @see #getenv() 1027 * @see ProcessBuilder#environment() 1028 */ 1029 public static String getenv(String name) { 1030 SecurityManager sm = getSecurityManager(); 1031 if (sm != null) { 1032 sm.checkPermission(new RuntimePermission("getenv."+name)); 1033 } 1034 1035 return ProcessEnvironment.getenv(name); 1036 } 1037 1038 1039 /** 1040 * Returns an unmodifiable string map view of the current system environment. 1041 * The environment is a system-dependent mapping from names to 1042 * values which is passed from parent to child processes. 1043 * 1044 * <p>If the system does not support environment variables, an 1045 * empty map is returned. 1046 * 1047 * <p>The returned map will never contain null keys or values. 1048 * Attempting to query the presence of a null key or value will 1049 * throw a {@link NullPointerException}. Attempting to query 1050 * the presence of a key or value which is not of type 1051 * {@link String} will throw a {@link ClassCastException}. 1052 * 1053 * <p>The returned map and its collection views may not obey the 1054 * general contract of the {@link Object#equals} and 1055 * {@link Object#hashCode} methods. 1056 * 1057 * <p>The returned map is typically case-sensitive on all platforms. 1058 * 1059 * <p>If a security manager exists, its 1060 * {@link SecurityManager#checkPermission checkPermission} 1061 * method is called with a 1062 * {@link RuntimePermission RuntimePermission("getenv.*")} permission. 1063 * This may result in a {@link SecurityException} being thrown. 1064 * 1065 * <p>When passing information to a Java subprocess, 1066 * <a href=#EnvironmentVSSystemProperties>system properties</a> 1067 * are generally preferred over environment variables. 1068 * 1069 * @return the environment as a map of variable names to values 1070 * @throws SecurityException 1071 * if a security manager exists and its 1072 * {@link SecurityManager#checkPermission checkPermission} 1073 * method doesn't allow access to the process environment 1074 * @see #getenv(String) 1075 * @see ProcessBuilder#environment() 1076 * @since 1.5 1077 */ 1078 public static java.util.Map<String,String> getenv() { 1079 SecurityManager sm = getSecurityManager(); 1080 if (sm != null) { 1081 sm.checkPermission(new RuntimePermission("getenv.*")); 1082 } 1083 1084 return ProcessEnvironment.getenv(); 1085 } 1086 1087 /** 1088 * {@code System.Logger} instances log messages that will be 1089 * routed to the underlying logging framework the {@link System.LoggerFinder 1090 * LoggerFinder} uses. 1091 * 1092 * {@code System.Logger} instances are typically obtained from 1093 * the {@link java.lang.System System} class, by calling 1094 * {@link java.lang.System#getLogger(java.lang.String) System.getLogger(loggerName)} 1095 * or {@link java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle) 1096 * System.getLogger(loggerName, bundle)}. 1097 * 1098 * @see java.lang.System#getLogger(java.lang.String) 1099 * @see java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle) 1100 * @see java.lang.System.LoggerFinder 1101 * 1102 * @since 9 1103 */ 1104 public interface Logger { 1105 1106 /** 1107 * System {@linkplain Logger loggers} levels. 1108 * 1109 * A level has a {@linkplain #getName() name} and {@linkplain 1110 * #getSeverity() severity}. 1111 * Level values are {@link #ALL}, {@link #TRACE}, {@link #DEBUG}, 1112 * {@link #INFO}, {@link #WARNING}, {@link #ERROR}, {@link #OFF}, 1113 * by order of increasing severity. 1114 * <br> 1115 * {@link #ALL} and {@link #OFF} 1116 * are simple markers with severities mapped respectively to 1117 * {@link java.lang.Integer#MIN_VALUE Integer.MIN_VALUE} and 1118 * {@link java.lang.Integer#MAX_VALUE Integer.MAX_VALUE}. 1119 * <p> 1120 * <b>Severity values and Mapping to {@code java.util.logging.Level}.</b> 1121 * <p> 1122 * {@linkplain System.Logger.Level System logger levels} are mapped to 1123 * {@linkplain java.util.logging.Level java.util.logging levels} 1124 * of corresponding severity. 1125 * <br>The mapping is as follows: 1126 * <br><br> 1127 * <table class="striped"> 1128 * <caption>System.Logger Severity Level Mapping</caption> 1129 * <thead> 1130 * <tr><th scope="col">System.Logger Levels</th> 1131 * <th scope="col">java.util.logging Levels</th> 1132 * </thead> 1133 * <tbody> 1134 * <tr><th scope="row">{@link Logger.Level#ALL ALL}</th> 1135 * <td>{@link java.util.logging.Level#ALL ALL}</td> 1136 * <tr><th scope="row">{@link Logger.Level#TRACE TRACE}</th> 1137 * <td>{@link java.util.logging.Level#FINER FINER}</td> 1138 * <tr><th scope="row">{@link Logger.Level#DEBUG DEBUG}</th> 1139 * <td>{@link java.util.logging.Level#FINE FINE}</td> 1140 * <tr><th scope="row">{@link Logger.Level#INFO INFO}</th> 1141 * <td>{@link java.util.logging.Level#INFO INFO}</td> 1142 * <tr><th scope="row">{@link Logger.Level#WARNING WARNING}</th> 1143 * <td>{@link java.util.logging.Level#WARNING WARNING}</td> 1144 * <tr><th scope="row">{@link Logger.Level#ERROR ERROR}</th> 1145 * <td>{@link java.util.logging.Level#SEVERE SEVERE}</td> 1146 * <tr><th scope="row">{@link Logger.Level#OFF OFF}</th> 1147 * <td>{@link java.util.logging.Level#OFF OFF}</td> 1148 * </tbody> 1149 * </table> 1150 * 1151 * @since 9 1152 * 1153 * @see java.lang.System.LoggerFinder 1154 * @see java.lang.System.Logger 1155 */ 1156 public enum Level { 1157 1158 // for convenience, we're reusing java.util.logging.Level int values 1159 // the mapping logic in sun.util.logging.PlatformLogger depends 1160 // on this. 1161 /** 1162 * A marker to indicate that all levels are enabled. 1163 * This level {@linkplain #getSeverity() severity} is 1164 * {@link Integer#MIN_VALUE}. 1165 */ 1166 ALL(Integer.MIN_VALUE), // typically mapped to/from j.u.l.Level.ALL 1167 /** 1168 * {@code TRACE} level: usually used to log diagnostic information. 1169 * This level {@linkplain #getSeverity() severity} is 1170 * {@code 400}. 1171 */ 1172 TRACE(400), // typically mapped to/from j.u.l.Level.FINER 1173 /** 1174 * {@code DEBUG} level: usually used to log debug information traces. 1175 * This level {@linkplain #getSeverity() severity} is 1176 * {@code 500}. 1177 */ 1178 DEBUG(500), // typically mapped to/from j.u.l.Level.FINEST/FINE/CONFIG 1179 /** 1180 * {@code INFO} level: usually used to log information messages. 1181 * This level {@linkplain #getSeverity() severity} is 1182 * {@code 800}. 1183 */ 1184 INFO(800), // typically mapped to/from j.u.l.Level.INFO 1185 /** 1186 * {@code WARNING} level: usually used to log warning messages. 1187 * This level {@linkplain #getSeverity() severity} is 1188 * {@code 900}. 1189 */ 1190 WARNING(900), // typically mapped to/from j.u.l.Level.WARNING 1191 /** 1192 * {@code ERROR} level: usually used to log error messages. 1193 * This level {@linkplain #getSeverity() severity} is 1194 * {@code 1000}. 1195 */ 1196 ERROR(1000), // typically mapped to/from j.u.l.Level.SEVERE 1197 /** 1198 * A marker to indicate that all levels are disabled. 1199 * This level {@linkplain #getSeverity() severity} is 1200 * {@link Integer#MAX_VALUE}. 1201 */ 1202 OFF(Integer.MAX_VALUE); // typically mapped to/from j.u.l.Level.OFF 1203 1204 private final int severity; 1205 1206 private Level(int severity) { 1207 this.severity = severity; 1208 } 1209 1210 /** 1211 * Returns the name of this level. 1212 * @return this level {@linkplain #name()}. 1213 */ 1214 public final String getName() { 1215 return name(); 1216 } 1217 1218 /** 1219 * Returns the severity of this level. 1220 * A higher severity means a more severe condition. 1221 * @return this level severity. 1222 */ 1223 public final int getSeverity() { 1224 return severity; 1225 } 1226 } 1227 1228 /** 1229 * Returns the name of this logger. 1230 * 1231 * @return the logger name. 1232 */ 1233 public String getName(); 1234 1235 /** 1236 * Checks if a message of the given level would be logged by 1237 * this logger. 1238 * 1239 * @param level the log message level. 1240 * @return {@code true} if the given log message level is currently 1241 * being logged. 1242 * 1243 * @throws NullPointerException if {@code level} is {@code null}. 1244 */ 1245 public boolean isLoggable(Level level); 1246 1247 /** 1248 * Logs a message. 1249 * 1250 * @implSpec The default implementation for this method calls 1251 * {@code this.log(level, (ResourceBundle)null, msg, (Object[])null);} 1252 * 1253 * @param level the log message level. 1254 * @param msg the string message (or a key in the message catalog, if 1255 * this logger is a {@link 1256 * LoggerFinder#getLocalizedLogger(java.lang.String, 1257 * java.util.ResourceBundle, java.lang.Module) localized logger}); 1258 * can be {@code null}. 1259 * 1260 * @throws NullPointerException if {@code level} is {@code null}. 1261 */ 1262 public default void log(Level level, String msg) { 1263 log(level, (ResourceBundle) null, msg, (Object[]) null); 1264 } 1265 1266 /** 1267 * Logs a lazily supplied message. 1268 * 1269 * If the logger is currently enabled for the given log message level 1270 * then a message is logged that is the result produced by the 1271 * given supplier function. Otherwise, the supplier is not operated on. 1272 * 1273 * @implSpec When logging is enabled for the given level, the default 1274 * implementation for this method calls 1275 * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), (Object[])null);} 1276 * 1277 * @param level the log message level. 1278 * @param msgSupplier a supplier function that produces a message. 1279 * 1280 * @throws NullPointerException if {@code level} is {@code null}, 1281 * or {@code msgSupplier} is {@code null}. 1282 */ 1283 public default void log(Level level, Supplier<String> msgSupplier) { 1284 Objects.requireNonNull(msgSupplier); 1285 if (isLoggable(Objects.requireNonNull(level))) { 1286 log(level, (ResourceBundle) null, msgSupplier.get(), (Object[]) null); 1287 } 1288 } 1289 1290 /** 1291 * Logs a message produced from the given object. 1292 * 1293 * If the logger is currently enabled for the given log message level then 1294 * a message is logged that, by default, is the result produced from 1295 * calling toString on the given object. 1296 * Otherwise, the object is not operated on. 1297 * 1298 * @implSpec When logging is enabled for the given level, the default 1299 * implementation for this method calls 1300 * {@code this.log(level, (ResourceBundle)null, obj.toString(), (Object[])null);} 1301 * 1302 * @param level the log message level. 1303 * @param obj the object to log. 1304 * 1305 * @throws NullPointerException if {@code level} is {@code null}, or 1306 * {@code obj} is {@code null}. 1307 */ 1308 public default void log(Level level, Object obj) { 1309 Objects.requireNonNull(obj); 1310 if (isLoggable(Objects.requireNonNull(level))) { 1311 this.log(level, (ResourceBundle) null, obj.toString(), (Object[]) null); 1312 } 1313 } 1314 1315 /** 1316 * Logs a message associated with a given throwable. 1317 * 1318 * @implSpec The default implementation for this method calls 1319 * {@code this.log(level, (ResourceBundle)null, msg, thrown);} 1320 * 1321 * @param level the log message level. 1322 * @param msg the string message (or a key in the message catalog, if 1323 * this logger is a {@link 1324 * LoggerFinder#getLocalizedLogger(java.lang.String, 1325 * java.util.ResourceBundle, java.lang.Module) localized logger}); 1326 * can be {@code null}. 1327 * @param thrown a {@code Throwable} associated with the log message; 1328 * can be {@code null}. 1329 * 1330 * @throws NullPointerException if {@code level} is {@code null}. 1331 */ 1332 public default void log(Level level, String msg, Throwable thrown) { 1333 this.log(level, null, msg, thrown); 1334 } 1335 1336 /** 1337 * Logs a lazily supplied message associated with a given throwable. 1338 * 1339 * If the logger is currently enabled for the given log message level 1340 * then a message is logged that is the result produced by the 1341 * given supplier function. Otherwise, the supplier is not operated on. 1342 * 1343 * @implSpec When logging is enabled for the given level, the default 1344 * implementation for this method calls 1345 * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), thrown);} 1346 * 1347 * @param level one of the log message level identifiers. 1348 * @param msgSupplier a supplier function that produces a message. 1349 * @param thrown a {@code Throwable} associated with log message; 1350 * can be {@code null}. 1351 * 1352 * @throws NullPointerException if {@code level} is {@code null}, or 1353 * {@code msgSupplier} is {@code null}. 1354 */ 1355 public default void log(Level level, Supplier<String> msgSupplier, 1356 Throwable thrown) { 1357 Objects.requireNonNull(msgSupplier); 1358 if (isLoggable(Objects.requireNonNull(level))) { 1359 this.log(level, null, msgSupplier.get(), thrown); 1360 } 1361 } 1362 1363 /** 1364 * Logs a message with an optional list of parameters. 1365 * 1366 * @implSpec The default implementation for this method calls 1367 * {@code this.log(level, (ResourceBundle)null, format, params);} 1368 * 1369 * @param level one of the log message level identifiers. 1370 * @param format the string message format in {@link 1371 * java.text.MessageFormat} format, (or a key in the message 1372 * catalog, if this logger is a {@link 1373 * LoggerFinder#getLocalizedLogger(java.lang.String, 1374 * java.util.ResourceBundle, java.lang.Module) localized logger}); 1375 * can be {@code null}. 1376 * @param params an optional list of parameters to the message (may be 1377 * none). 1378 * 1379 * @throws NullPointerException if {@code level} is {@code null}. 1380 */ 1381 public default void log(Level level, String format, Object... params) { 1382 this.log(level, null, format, params); 1383 } 1384 1385 /** 1386 * Logs a localized message associated with a given throwable. 1387 * 1388 * If the given resource bundle is non-{@code null}, the {@code msg} 1389 * string is localized using the given resource bundle. 1390 * Otherwise the {@code msg} string is not localized. 1391 * 1392 * @param level the log message level. 1393 * @param bundle a resource bundle to localize {@code msg}; can be 1394 * {@code null}. 1395 * @param msg the string message (or a key in the message catalog, 1396 * if {@code bundle} is not {@code null}); can be {@code null}. 1397 * @param thrown a {@code Throwable} associated with the log message; 1398 * can be {@code null}. 1399 * 1400 * @throws NullPointerException if {@code level} is {@code null}. 1401 */ 1402 public void log(Level level, ResourceBundle bundle, String msg, 1403 Throwable thrown); 1404 1405 /** 1406 * Logs a message with resource bundle and an optional list of 1407 * parameters. 1408 * 1409 * If the given resource bundle is non-{@code null}, the {@code format} 1410 * string is localized using the given resource bundle. 1411 * Otherwise the {@code format} string is not localized. 1412 * 1413 * @param level the log message level. 1414 * @param bundle a resource bundle to localize {@code format}; can be 1415 * {@code null}. 1416 * @param format the string message format in {@link 1417 * java.text.MessageFormat} format, (or a key in the message 1418 * catalog if {@code bundle} is not {@code null}); can be {@code null}. 1419 * @param params an optional list of parameters to the message (may be 1420 * none). 1421 * 1422 * @throws NullPointerException if {@code level} is {@code null}. 1423 */ 1424 public void log(Level level, ResourceBundle bundle, String format, 1425 Object... params); 1426 } 1427 1428 /** 1429 * The {@code LoggerFinder} service is responsible for creating, managing, 1430 * and configuring loggers to the underlying framework it uses. 1431 * 1432 * A logger finder is a concrete implementation of this class that has a 1433 * zero-argument constructor and implements the abstract methods defined 1434 * by this class. 1435 * The loggers returned from a logger finder are capable of routing log 1436 * messages to the logging backend this provider supports. 1437 * A given invocation of the Java Runtime maintains a single 1438 * system-wide LoggerFinder instance that is loaded as follows: 1439 * <ul> 1440 * <li>First it finds any custom {@code LoggerFinder} provider 1441 * using the {@link java.util.ServiceLoader} facility with the 1442 * {@linkplain ClassLoader#getSystemClassLoader() system class 1443 * loader}.</li> 1444 * <li>If no {@code LoggerFinder} provider is found, the system default 1445 * {@code LoggerFinder} implementation will be used.</li> 1446 * </ul> 1447 * <p> 1448 * An application can replace the logging backend 1449 * <i>even when the java.logging module is present</i>, by simply providing 1450 * and declaring an implementation of the {@link LoggerFinder} service. 1451 * <p> 1452 * <b>Default Implementation</b> 1453 * <p> 1454 * The system default {@code LoggerFinder} implementation uses 1455 * {@code java.util.logging} as the backend framework when the 1456 * {@code java.logging} module is present. 1457 * It returns a {@linkplain System.Logger logger} instance 1458 * that will route log messages to a {@link java.util.logging.Logger 1459 * java.util.logging.Logger}. Otherwise, if {@code java.logging} is not 1460 * present, the default implementation will return a simple logger 1461 * instance that will route log messages of {@code INFO} level and above to 1462 * the console ({@code System.err}). 1463 * <p> 1464 * <b>Logging Configuration</b> 1465 * <p> 1466 * {@linkplain Logger Logger} instances obtained from the 1467 * {@code LoggerFinder} factory methods are not directly configurable by 1468 * the application. Configuration is the responsibility of the underlying 1469 * logging backend, and usually requires using APIs specific to that backend. 1470 * <p>For the default {@code LoggerFinder} implementation 1471 * using {@code java.util.logging} as its backend, refer to 1472 * {@link java.util.logging java.util.logging} for logging configuration. 1473 * For the default {@code LoggerFinder} implementation returning simple loggers 1474 * when the {@code java.logging} module is absent, the configuration 1475 * is implementation dependent. 1476 * <p> 1477 * Usually an application that uses a logging framework will log messages 1478 * through a logger facade defined (or supported) by that framework. 1479 * Applications that wish to use an external framework should log 1480 * through the facade associated with that framework. 1481 * <p> 1482 * A system class that needs to log messages will typically obtain 1483 * a {@link System.Logger} instance to route messages to the logging 1484 * framework selected by the application. 1485 * <p> 1486 * Libraries and classes that only need loggers to produce log messages 1487 * should not attempt to configure loggers by themselves, as that 1488 * would make them dependent from a specific implementation of the 1489 * {@code LoggerFinder} service. 1490 * <p> 1491 * In addition, when a security manager is present, loggers provided to 1492 * system classes should not be directly configurable through the logging 1493 * backend without requiring permissions. 1494 * <br> 1495 * It is the responsibility of the provider of 1496 * the concrete {@code LoggerFinder} implementation to ensure that 1497 * these loggers are not configured by untrusted code without proper 1498 * permission checks, as configuration performed on such loggers usually 1499 * affects all applications in the same Java Runtime. 1500 * <p> 1501 * <b>Message Levels and Mapping to backend levels</b> 1502 * <p> 1503 * A logger finder is responsible for mapping from a {@code 1504 * System.Logger.Level} to a level supported by the logging backend it uses. 1505 * <br>The default LoggerFinder using {@code java.util.logging} as the backend 1506 * maps {@code System.Logger} levels to 1507 * {@linkplain java.util.logging.Level java.util.logging} levels 1508 * of corresponding severity - as described in {@link Logger.Level 1509 * Logger.Level}. 1510 * 1511 * @see java.lang.System 1512 * @see java.lang.System.Logger 1513 * 1514 * @since 9 1515 */ 1516 public static abstract class LoggerFinder { 1517 /** 1518 * The {@code RuntimePermission("loggerFinder")} is 1519 * necessary to subclass and instantiate the {@code LoggerFinder} class, 1520 * as well as to obtain loggers from an instance of that class. 1521 */ 1522 static final RuntimePermission LOGGERFINDER_PERMISSION = 1523 new RuntimePermission("loggerFinder"); 1524 1525 /** 1526 * Creates a new instance of {@code LoggerFinder}. 1527 * 1528 * @implNote It is recommended that a {@code LoggerFinder} service 1529 * implementation does not perform any heavy initialization in its 1530 * constructor, in order to avoid possible risks of deadlock or class 1531 * loading cycles during the instantiation of the service provider. 1532 * 1533 * @throws SecurityException if a security manager is present and its 1534 * {@code checkPermission} method doesn't allow the 1535 * {@code RuntimePermission("loggerFinder")}. 1536 */ 1537 protected LoggerFinder() { 1538 this(checkPermission()); 1539 } 1540 1541 private LoggerFinder(Void unused) { 1542 // nothing to do. 1543 } 1544 1545 private static Void checkPermission() { 1546 final SecurityManager sm = System.getSecurityManager(); 1547 if (sm != null) { 1548 sm.checkPermission(LOGGERFINDER_PERMISSION); 1549 } 1550 return null; 1551 } 1552 1553 /** 1554 * Returns an instance of {@link Logger Logger} 1555 * for the given {@code module}. 1556 * 1557 * @param name the name of the logger. 1558 * @param module the module for which the logger is being requested. 1559 * 1560 * @return a {@link Logger logger} suitable for use within the given 1561 * module. 1562 * @throws NullPointerException if {@code name} is {@code null} or 1563 * {@code module} is {@code null}. 1564 * @throws SecurityException if a security manager is present and its 1565 * {@code checkPermission} method doesn't allow the 1566 * {@code RuntimePermission("loggerFinder")}. 1567 */ 1568 public abstract Logger getLogger(String name, Module module); 1569 1570 /** 1571 * Returns a localizable instance of {@link Logger Logger} 1572 * for the given {@code module}. 1573 * The returned logger will use the provided resource bundle for 1574 * message localization. 1575 * 1576 * @implSpec By default, this method calls {@link 1577 * #getLogger(java.lang.String, java.lang.Module) 1578 * this.getLogger(name, module)} to obtain a logger, then wraps that 1579 * logger in a {@link Logger} instance where all methods that do not 1580 * take a {@link ResourceBundle} as parameter are redirected to one 1581 * which does - passing the given {@code bundle} for 1582 * localization. So for instance, a call to {@link 1583 * Logger#log(Logger.Level, String) Logger.log(Level.INFO, msg)} 1584 * will end up as a call to {@link 1585 * Logger#log(Logger.Level, ResourceBundle, String, Object...) 1586 * Logger.log(Level.INFO, bundle, msg, (Object[])null)} on the wrapped 1587 * logger instance. 1588 * Note however that by default, string messages returned by {@link 1589 * java.util.function.Supplier Supplier<String>} will not be 1590 * localized, as it is assumed that such strings are messages which are 1591 * already constructed, rather than keys in a resource bundle. 1592 * <p> 1593 * An implementation of {@code LoggerFinder} may override this method, 1594 * for example, when the underlying logging backend provides its own 1595 * mechanism for localizing log messages, then such a 1596 * {@code LoggerFinder} would be free to return a logger 1597 * that makes direct use of the mechanism provided by the backend. 1598 * 1599 * @param name the name of the logger. 1600 * @param bundle a resource bundle; can be {@code null}. 1601 * @param module the module for which the logger is being requested. 1602 * @return an instance of {@link Logger Logger} which will use the 1603 * provided resource bundle for message localization. 1604 * 1605 * @throws NullPointerException if {@code name} is {@code null} or 1606 * {@code module} is {@code null}. 1607 * @throws SecurityException if a security manager is present and its 1608 * {@code checkPermission} method doesn't allow the 1609 * {@code RuntimePermission("loggerFinder")}. 1610 */ 1611 public Logger getLocalizedLogger(String name, ResourceBundle bundle, 1612 Module module) { 1613 return new LocalizedLoggerWrapper<>(getLogger(name, module), bundle); 1614 } 1615 1616 /** 1617 * Returns the {@code LoggerFinder} instance. There is one 1618 * single system-wide {@code LoggerFinder} instance in 1619 * the Java Runtime. See the class specification of how the 1620 * {@link LoggerFinder LoggerFinder} implementation is located and 1621 * loaded. 1622 1623 * @return the {@link LoggerFinder LoggerFinder} instance. 1624 * @throws SecurityException if a security manager is present and its 1625 * {@code checkPermission} method doesn't allow the 1626 * {@code RuntimePermission("loggerFinder")}. 1627 */ 1628 public static LoggerFinder getLoggerFinder() { 1629 final SecurityManager sm = System.getSecurityManager(); 1630 if (sm != null) { 1631 sm.checkPermission(LOGGERFINDER_PERMISSION); 1632 } 1633 return accessProvider(); 1634 } 1635 1636 1637 private static volatile LoggerFinder service; 1638 static LoggerFinder accessProvider() { 1639 // We do not need to synchronize: LoggerFinderLoader will 1640 // always return the same instance, so if we don't have it, 1641 // just fetch it again. 1642 if (service == null) { 1643 PrivilegedAction<LoggerFinder> pa = 1644 () -> LoggerFinderLoader.getLoggerFinder(); 1645 service = AccessController.doPrivileged(pa, null, 1646 LOGGERFINDER_PERMISSION); 1647 } 1648 return service; 1649 } 1650 1651 } 1652 1653 1654 /** 1655 * Returns an instance of {@link Logger Logger} for the caller's 1656 * use. 1657 * 1658 * @implSpec 1659 * Instances returned by this method route messages to loggers 1660 * obtained by calling {@link LoggerFinder#getLogger(java.lang.String, 1661 * java.lang.Module) LoggerFinder.getLogger(name, module)}, where 1662 * {@code module} is the caller's module. 1663 * In cases where {@code System.getLogger} is called from a context where 1664 * there is no caller frame on the stack (e.g when called directly 1665 * from a JNI attached thread), {@code IllegalCallerException} is thrown. 1666 * To obtain a logger in such a context, use an auxiliary class that will 1667 * implicitly be identified as the caller, or use the system {@link 1668 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead. 1669 * Note that doing the latter may eagerly initialize the underlying 1670 * logging system. 1671 * 1672 * @apiNote 1673 * This method may defer calling the {@link 1674 * LoggerFinder#getLogger(java.lang.String, java.lang.Module) 1675 * LoggerFinder.getLogger} method to create an actual logger supplied by 1676 * the logging backend, for instance, to allow loggers to be obtained during 1677 * the system initialization time. 1678 * 1679 * @param name the name of the logger. 1680 * @return an instance of {@link Logger} that can be used by the calling 1681 * class. 1682 * @throws NullPointerException if {@code name} is {@code null}. 1683 * @throws IllegalCallerException if there is no Java caller frame on the 1684 * stack. 1685 * 1686 * @since 9 1687 */ 1688 @CallerSensitive 1689 public static Logger getLogger(String name) { 1690 Objects.requireNonNull(name); 1691 final Class<?> caller = Reflection.getCallerClass(); 1692 if (caller == null) { 1693 throw new IllegalCallerException("no caller frame"); 1694 } 1695 return LazyLoggers.getLogger(name, caller.getModule()); 1696 } 1697 1698 /** 1699 * Returns a localizable instance of {@link Logger 1700 * Logger} for the caller's use. 1701 * The returned logger will use the provided resource bundle for message 1702 * localization. 1703 * 1704 * @implSpec 1705 * The returned logger will perform message localization as specified 1706 * by {@link LoggerFinder#getLocalizedLogger(java.lang.String, 1707 * java.util.ResourceBundle, java.lang.Module) 1708 * LoggerFinder.getLocalizedLogger(name, bundle, module)}, where 1709 * {@code module} is the caller's module. 1710 * In cases where {@code System.getLogger} is called from a context where 1711 * there is no caller frame on the stack (e.g when called directly 1712 * from a JNI attached thread), {@code IllegalCallerException} is thrown. 1713 * To obtain a logger in such a context, use an auxiliary class that 1714 * will implicitly be identified as the caller, or use the system {@link 1715 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead. 1716 * Note that doing the latter may eagerly initialize the underlying 1717 * logging system. 1718 * 1719 * @apiNote 1720 * This method is intended to be used after the system is fully initialized. 1721 * This method may trigger the immediate loading and initialization 1722 * of the {@link LoggerFinder} service, which may cause issues if the 1723 * Java Runtime is not ready to initialize the concrete service 1724 * implementation yet. 1725 * System classes which may be loaded early in the boot sequence and 1726 * need to log localized messages should create a logger using 1727 * {@link #getLogger(java.lang.String)} and then use the log methods that 1728 * take a resource bundle as parameter. 1729 * 1730 * @param name the name of the logger. 1731 * @param bundle a resource bundle. 1732 * @return an instance of {@link Logger} which will use the provided 1733 * resource bundle for message localization. 1734 * @throws NullPointerException if {@code name} is {@code null} or 1735 * {@code bundle} is {@code null}. 1736 * @throws IllegalCallerException if there is no Java caller frame on the 1737 * stack. 1738 * 1739 * @since 9 1740 */ 1741 @CallerSensitive 1742 public static Logger getLogger(String name, ResourceBundle bundle) { 1743 final ResourceBundle rb = Objects.requireNonNull(bundle); 1744 Objects.requireNonNull(name); 1745 final Class<?> caller = Reflection.getCallerClass(); 1746 if (caller == null) { 1747 throw new IllegalCallerException("no caller frame"); 1748 } 1749 final SecurityManager sm = System.getSecurityManager(); 1750 // We don't use LazyLoggers if a resource bundle is specified. 1751 // Bootstrap sensitive classes in the JDK do not use resource bundles 1752 // when logging. This could be revisited later, if it needs to. 1753 if (sm != null) { 1754 final PrivilegedAction<Logger> pa = 1755 () -> LoggerFinder.accessProvider() 1756 .getLocalizedLogger(name, rb, caller.getModule()); 1757 return AccessController.doPrivileged(pa, null, 1758 LoggerFinder.LOGGERFINDER_PERMISSION); 1759 } 1760 return LoggerFinder.accessProvider() 1761 .getLocalizedLogger(name, rb, caller.getModule()); 1762 } 1763 1764 /** 1765 * Terminates the currently running Java Virtual Machine. The 1766 * argument serves as a status code; by convention, a nonzero status 1767 * code indicates abnormal termination. 1768 * <p> 1769 * This method calls the {@code exit} method in class 1770 * {@code Runtime}. This method never returns normally. 1771 * <p> 1772 * The call {@code System.exit(n)} is effectively equivalent to 1773 * the call: 1774 * <blockquote><pre> 1775 * Runtime.getRuntime().exit(n) 1776 * </pre></blockquote> 1777 * 1778 * @param status exit status. 1779 * @throws SecurityException 1780 * if a security manager exists and its {@code checkExit} 1781 * method doesn't allow exit with the specified status. 1782 * @see java.lang.Runtime#exit(int) 1783 */ 1784 public static void exit(int status) { 1785 Runtime.getRuntime().exit(status); 1786 } 1787 1788 /** 1789 * Runs the garbage collector in the Java Virtual Machine. 1790 * <p> 1791 * Calling the {@code gc} method suggests that the Java Virtual Machine 1792 * expend effort toward recycling unused objects in order to 1793 * make the memory they currently occupy available for reuse 1794 * by the Java Virtual Machine. 1795 * When control returns from the method call, the Java Virtual Machine 1796 * has made a best effort to reclaim space from all unused objects. 1797 * There is no guarantee that this effort will recycle any particular 1798 * number of unused objects, reclaim any particular amount of space, or 1799 * complete at any particular time, if at all, before the method returns or ever. 1800 * <p> 1801 * The call {@code System.gc()} is effectively equivalent to the 1802 * call: 1803 * <blockquote><pre> 1804 * Runtime.getRuntime().gc() 1805 * </pre></blockquote> 1806 * 1807 * @see java.lang.Runtime#gc() 1808 */ 1809 public static void gc() { 1810 Runtime.getRuntime().gc(); 1811 } 1812 1813 /** 1814 * Runs the finalization methods of any objects pending finalization. 1815 * 1816 * Calling this method suggests that the Java Virtual Machine expend 1817 * effort toward running the {@code finalize} methods of objects 1818 * that have been found to be discarded but whose {@code finalize} 1819 * methods have not yet been run. When control returns from the 1820 * method call, the Java Virtual Machine has made a best effort to 1821 * complete all outstanding finalizations. 1822 * <p> 1823 * The call {@code System.runFinalization()} is effectively 1824 * equivalent to the call: 1825 * <blockquote><pre> 1826 * Runtime.getRuntime().runFinalization() 1827 * </pre></blockquote> 1828 * 1829 * @see java.lang.Runtime#runFinalization() 1830 */ 1831 public static void runFinalization() { 1832 Runtime.getRuntime().runFinalization(); 1833 } 1834 1835 /** 1836 * Loads the native library specified by the filename argument. The filename 1837 * argument must be an absolute path name. 1838 * 1839 * If the filename argument, when stripped of any platform-specific library 1840 * prefix, path, and file extension, indicates a library whose name is, 1841 * for example, L, and a native library called L is statically linked 1842 * with the VM, then the JNI_OnLoad_L function exported by the library 1843 * is invoked rather than attempting to load a dynamic library. 1844 * A filename matching the argument does not have to exist in the 1845 * file system. 1846 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a> 1847 * for more details. 1848 * 1849 * Otherwise, the filename argument is mapped to a native library image in 1850 * an implementation-dependent manner. 1851 * 1852 * <p> 1853 * The call {@code System.load(name)} is effectively equivalent 1854 * to the call: 1855 * <blockquote><pre> 1856 * Runtime.getRuntime().load(name) 1857 * </pre></blockquote> 1858 * 1859 * @param filename the file to load. 1860 * @throws SecurityException if a security manager exists and its 1861 * {@code checkLink} method doesn't allow 1862 * loading of the specified dynamic library 1863 * @throws UnsatisfiedLinkError if either the filename is not an 1864 * absolute path name, the native library is not statically 1865 * linked with the VM, or the library cannot be mapped to 1866 * a native library image by the host system. 1867 * @throws NullPointerException if {@code filename} is {@code null} 1868 * @see java.lang.Runtime#load(java.lang.String) 1869 * @see java.lang.SecurityManager#checkLink(java.lang.String) 1870 */ 1871 @CallerSensitive 1872 public static void load(String filename) { 1873 Runtime.getRuntime().load0(Reflection.getCallerClass(), filename); 1874 } 1875 1876 /** 1877 * Loads the native library specified by the {@code libname} 1878 * argument. The {@code libname} argument must not contain any platform 1879 * specific prefix, file extension or path. If a native library 1880 * called {@code libname} is statically linked with the VM, then the 1881 * JNI_OnLoad_{@code libname} function exported by the library is invoked. 1882 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a> 1883 * for more details. 1884 * 1885 * Otherwise, the libname argument is loaded from a system library 1886 * location and mapped to a native library image in an implementation- 1887 * dependent manner. 1888 * <p> 1889 * The call {@code System.loadLibrary(name)} is effectively 1890 * equivalent to the call 1891 * <blockquote><pre> 1892 * Runtime.getRuntime().loadLibrary(name) 1893 * </pre></blockquote> 1894 * 1895 * @param libname the name of the library. 1896 * @throws SecurityException if a security manager exists and its 1897 * {@code checkLink} method doesn't allow 1898 * loading of the specified dynamic library 1899 * @throws UnsatisfiedLinkError if either the libname argument 1900 * contains a file path, the native library is not statically 1901 * linked with the VM, or the library cannot be mapped to a 1902 * native library image by the host system. 1903 * @throws NullPointerException if {@code libname} is {@code null} 1904 * @see java.lang.Runtime#loadLibrary(java.lang.String) 1905 * @see java.lang.SecurityManager#checkLink(java.lang.String) 1906 */ 1907 @CallerSensitive 1908 public static void loadLibrary(String libname) { 1909 Runtime.getRuntime().loadLibrary0(Reflection.getCallerClass(), libname); 1910 } 1911 1912 /** 1913 * Maps a library name into a platform-specific string representing 1914 * a native library. 1915 * 1916 * @param libname the name of the library. 1917 * @return a platform-dependent native library name. 1918 * @throws NullPointerException if {@code libname} is {@code null} 1919 * @see java.lang.System#loadLibrary(java.lang.String) 1920 * @see java.lang.ClassLoader#findLibrary(java.lang.String) 1921 * @since 1.2 1922 */ 1923 public static native String mapLibraryName(String libname); 1924 1925 /** 1926 * Create PrintStream for stdout/err based on encoding. 1927 */ 1928 private static PrintStream newPrintStream(FileOutputStream fos, String enc) { 1929 if (enc != null) { 1930 try { 1931 return new PrintStream(new BufferedOutputStream(fos, 128), true, enc); 1932 } catch (UnsupportedEncodingException uee) {} 1933 } 1934 return new PrintStream(new BufferedOutputStream(fos, 128), true); 1935 } 1936 1937 /** 1938 * Logs an exception/error at initialization time to stdout or stderr. 1939 * 1940 * @param printToStderr to print to stderr rather than stdout 1941 * @param printStackTrace to print the stack trace 1942 * @param msg the message to print before the exception, can be {@code null} 1943 * @param e the exception or error 1944 */ 1945 private static void logInitException(boolean printToStderr, 1946 boolean printStackTrace, 1947 String msg, 1948 Throwable e) { 1949 if (VM.initLevel() < 1) { 1950 throw new InternalError("system classes not initialized"); 1951 } 1952 PrintStream log = (printToStderr) ? err : out; 1953 if (msg != null) { 1954 log.println(msg); 1955 } 1956 if (printStackTrace) { 1957 e.printStackTrace(log); 1958 } else { 1959 log.println(e); 1960 for (Throwable suppressed : e.getSuppressed()) { 1961 log.println("Suppressed: " + suppressed); 1962 } 1963 Throwable cause = e.getCause(); 1964 if (cause != null) { 1965 log.println("Caused by: " + cause); 1966 } 1967 } 1968 } 1969 1970 /** 1971 * Create the Properties object from a map - masking out system properties 1972 * that are not intended for public access. 1973 */ 1974 private static Properties createProperties(Map<String, String> initialProps) { 1975 Properties properties = new Properties(initialProps.size()); 1976 for (var entry : initialProps.entrySet()) { 1977 String prop = entry.getKey(); 1978 switch (prop) { 1979 // Do not add private system properties to the Properties 1980 case "sun.nio.MaxDirectMemorySize": 1981 case "sun.nio.PageAlignDirectMemory": 1982 // used by java.lang.Integer.IntegerCache 1983 case "java.lang.Integer.IntegerCache.high": 1984 // used by sun.launcher.LauncherHelper 1985 case "sun.java.launcher.diag": 1986 // used by jdk.internal.loader.ClassLoaders 1987 case "jdk.boot.class.path.append": 1988 break; 1989 default: 1990 properties.put(prop, entry.getValue()); 1991 } 1992 } 1993 return properties; 1994 } 1995 1996 /** 1997 * Initialize the system class. Called after thread initialization. 1998 */ 1999 private static void initPhase1() { 2000 // VM might invoke JNU_NewStringPlatform() to set those encoding 2001 // sensitive properties (user.home, user.name, boot.class.path, etc.) 2002 // during "props" initialization. 2003 // The charset is initialized in System.c and does not depend on the Properties. 2004 Map<String, String> tempProps = SystemProps.initProperties(); 2005 VersionProps.init(tempProps); 2006 2007 // There are certain system configurations that may be controlled by 2008 // VM options such as the maximum amount of direct memory and 2009 // Integer cache size used to support the object identity semantics 2010 // of autoboxing. Typically, the library will obtain these values 2011 // from the properties set by the VM. If the properties are for 2012 // internal implementation use only, these properties should be 2013 // masked from the system properties. 2014 // 2015 // Save a private copy of the system properties object that 2016 // can only be accessed by the internal implementation. 2017 VM.saveProperties(tempProps); 2018 props = createProperties(tempProps); 2019 2020 StaticProperty.javaHome(); // Load StaticProperty to cache the property values 2021 2022 lineSeparator = props.getProperty("line.separator"); 2023 2024 FileInputStream fdIn = new FileInputStream(FileDescriptor.in); 2025 FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out); 2026 FileOutputStream fdErr = new FileOutputStream(FileDescriptor.err); 2027 setIn0(new BufferedInputStream(fdIn)); 2028 setOut0(newPrintStream(fdOut, props.getProperty("sun.stdout.encoding"))); 2029 setErr0(newPrintStream(fdErr, props.getProperty("sun.stderr.encoding"))); 2030 2031 // Setup Java signal handlers for HUP, TERM, and INT (where available). 2032 Terminator.setup(); 2033 2034 // Initialize any miscellaneous operating system settings that need to be 2035 // set for the class libraries. Currently this is no-op everywhere except 2036 // for Windows where the process-wide error mode is set before the java.io 2037 // classes are used. 2038 VM.initializeOSEnvironment(); 2039 2040 // The main thread is not added to its thread group in the same 2041 // way as other threads; we must do it ourselves here. 2042 Thread current = Thread.currentThread(); 2043 current.getThreadGroup().add(current); 2044 2045 // register shared secrets 2046 setJavaLangAccess(); 2047 2048 ClassLoader.initLibraryPaths(); 2049 2050 // Subsystems that are invoked during initialization can invoke 2051 // VM.isBooted() in order to avoid doing things that should 2052 // wait until the VM is fully initialized. The initialization level 2053 // is incremented from 0 to 1 here to indicate the first phase of 2054 // initialization has completed. 2055 // IMPORTANT: Ensure that this remains the last initialization action! 2056 VM.initLevel(1); 2057 } 2058 2059 // @see #initPhase2() 2060 static ModuleLayer bootLayer; 2061 2062 /* 2063 * Invoked by VM. Phase 2 module system initialization. 2064 * Only classes in java.base can be loaded in this phase. 2065 * 2066 * @param printToStderr print exceptions to stderr rather than stdout 2067 * @param printStackTrace print stack trace when exception occurs 2068 * 2069 * @return JNI_OK for success, JNI_ERR for failure 2070 */ 2071 private static int initPhase2(boolean printToStderr, boolean printStackTrace) { 2072 try { 2073 bootLayer = ModuleBootstrap.boot(); 2074 } catch (Exception | Error e) { 2075 logInitException(printToStderr, printStackTrace, 2076 "Error occurred during initialization of boot layer", e); 2077 return -1; // JNI_ERR 2078 } 2079 2080 // module system initialized 2081 VM.initLevel(2); 2082 2083 return 0; // JNI_OK 2084 } 2085 2086 /* 2087 * Invoked by VM. Phase 3 is the final system initialization: 2088 * 1. set security manager 2089 * 2. set system class loader 2090 * 3. set TCCL 2091 * 2092 * This method must be called after the module system initialization. 2093 * The security manager and system class loader may be a custom class from 2094 * the application classpath or modulepath. 2095 */ 2096 private static void initPhase3() { 2097 String smProp = System.getProperty("java.security.manager"); 2098 if (smProp != null) { 2099 switch (smProp) { 2100 case "disallow": 2101 allowSecurityManager = NEVER; 2102 break; 2103 case "allow": 2104 allowSecurityManager = MAYBE; 2105 break; 2106 case "": 2107 case "default": 2108 setSecurityManager(new SecurityManager()); 2109 allowSecurityManager = MAYBE; 2110 break; 2111 default: 2112 try { 2113 ClassLoader cl = ClassLoader.getBuiltinAppClassLoader(); 2114 Class<?> c = Class.forName(smProp, false, cl); 2115 Constructor<?> ctor = c.getConstructor(); 2116 // Must be a public subclass of SecurityManager with 2117 // a public no-arg constructor 2118 if (!SecurityManager.class.isAssignableFrom(c) || 2119 !Modifier.isPublic(c.getModifiers()) || 2120 !Modifier.isPublic(ctor.getModifiers())) { 2121 throw new Error("Could not create SecurityManager: " 2122 + ctor.toString()); 2123 } 2124 // custom security manager may be in non-exported package 2125 ctor.setAccessible(true); 2126 SecurityManager sm = (SecurityManager) ctor.newInstance(); 2127 setSecurityManager(sm); 2128 } catch (Exception e) { 2129 throw new InternalError("Could not create SecurityManager", e); 2130 } 2131 allowSecurityManager = MAYBE; 2132 } 2133 } else { 2134 allowSecurityManager = MAYBE; 2135 } 2136 2137 // initializing the system class loader 2138 VM.initLevel(3); 2139 2140 // system class loader initialized 2141 ClassLoader scl = ClassLoader.initSystemClassLoader(); 2142 2143 // set TCCL 2144 Thread.currentThread().setContextClassLoader(scl); 2145 2146 // system is fully initialized 2147 VM.initLevel(4); 2148 } 2149 2150 private static void setJavaLangAccess() { 2151 // Allow privileged classes outside of java.lang 2152 SharedSecrets.setJavaLangAccess(new JavaLangAccess() { 2153 public List<Method> getDeclaredPublicMethods(Class<?> klass, String name, Class<?>... parameterTypes) { 2154 return klass.getDeclaredPublicMethods(name, parameterTypes); 2155 } 2156 public jdk.internal.reflect.ConstantPool getConstantPool(Class<?> klass) { 2157 return klass.getConstantPool(); 2158 } 2159 public boolean casAnnotationType(Class<?> klass, AnnotationType oldType, AnnotationType newType) { 2160 return klass.casAnnotationType(oldType, newType); 2161 } 2162 public AnnotationType getAnnotationType(Class<?> klass) { 2163 return klass.getAnnotationType(); 2164 } 2165 public Map<Class<? extends Annotation>, Annotation> getDeclaredAnnotationMap(Class<?> klass) { 2166 return klass.getDeclaredAnnotationMap(); 2167 } 2168 public byte[] getRawClassAnnotations(Class<?> klass) { 2169 return klass.getRawAnnotations(); 2170 } 2171 public byte[] getRawClassTypeAnnotations(Class<?> klass) { 2172 return klass.getRawTypeAnnotations(); 2173 } 2174 public byte[] getRawExecutableTypeAnnotations(Executable executable) { 2175 return Class.getExecutableTypeAnnotationBytes(executable); 2176 } 2177 public <E extends Enum<E>> 2178 E[] getEnumConstantsShared(Class<E> klass) { 2179 return klass.getEnumConstantsShared(); 2180 } 2181 public void blockedOn(Interruptible b) { 2182 Thread.blockedOn(b); 2183 } 2184 public void registerShutdownHook(int slot, boolean registerShutdownInProgress, Runnable hook) { 2185 Shutdown.add(slot, registerShutdownInProgress, hook); 2186 } 2187 public Thread newThreadWithAcc(Runnable target, AccessControlContext acc) { 2188 return new Thread(target, acc); 2189 } 2190 @SuppressWarnings("deprecation") 2191 public void invokeFinalize(Object o) throws Throwable { 2192 o.finalize(); 2193 } 2194 public ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap(ClassLoader cl) { 2195 return cl.createOrGetClassLoaderValueMap(); 2196 } 2197 public Class<?> defineClass(ClassLoader loader, String name, byte[] b, ProtectionDomain pd, String source) { 2198 return ClassLoader.defineClass1(loader, name, b, 0, b.length, pd, source); 2199 } 2200 public Class<?> defineClass(ClassLoader loader, Class<?> lookup, String name, byte[] b, ProtectionDomain pd, 2201 boolean initialize, int flags, Object classData) { 2202 return ClassLoader.defineClass0(loader, lookup, name, b, 0, b.length, pd, initialize, flags, classData); 2203 } 2204 public Class<?> findBootstrapClassOrNull(ClassLoader cl, String name) { 2205 return cl.findBootstrapClassOrNull(name); 2206 } 2207 public Package definePackage(ClassLoader cl, String name, Module module) { 2208 return cl.definePackage(name, module); 2209 } 2210 public String fastUUID(long lsb, long msb) { 2211 return Long.fastUUID(lsb, msb); 2212 } 2213 public void addNonExportedPackages(ModuleLayer layer) { 2214 SecurityManager.addNonExportedPackages(layer); 2215 } 2216 public void invalidatePackageAccessCache() { 2217 SecurityManager.invalidatePackageAccessCache(); 2218 } 2219 public Module defineModule(ClassLoader loader, 2220 ModuleDescriptor descriptor, 2221 URI uri) { 2222 return new Module(null, loader, descriptor, uri); 2223 } 2224 public Module defineUnnamedModule(ClassLoader loader) { 2225 return new Module(loader); 2226 } 2227 public void addReads(Module m1, Module m2) { 2228 m1.implAddReads(m2); 2229 } 2230 public void addReadsAllUnnamed(Module m) { 2231 m.implAddReadsAllUnnamed(); 2232 } 2233 public void addExports(Module m, String pn, Module other) { 2234 m.implAddExports(pn, other); 2235 } 2236 public void addExportsToAllUnnamed(Module m, String pn) { 2237 m.implAddExportsToAllUnnamed(pn); 2238 } 2239 public void addOpens(Module m, String pn, Module other) { 2240 m.implAddOpens(pn, other); 2241 } 2242 public void addOpensToAllUnnamed(Module m, String pn) { 2243 m.implAddOpensToAllUnnamed(pn); 2244 } 2245 public void addOpensToAllUnnamed(Module m, Iterator<String> packages) { 2246 m.implAddOpensToAllUnnamed(packages); 2247 } 2248 public void addUses(Module m, Class<?> service) { 2249 m.implAddUses(service); 2250 } 2251 public boolean isReflectivelyExported(Module m, String pn, Module other) { 2252 return m.isReflectivelyExported(pn, other); 2253 } 2254 public boolean isReflectivelyOpened(Module m, String pn, Module other) { 2255 return m.isReflectivelyOpened(pn, other); 2256 } 2257 public ServicesCatalog getServicesCatalog(ModuleLayer layer) { 2258 return layer.getServicesCatalog(); 2259 } 2260 public Stream<ModuleLayer> layers(ModuleLayer layer) { 2261 return layer.layers(); 2262 } 2263 public Stream<ModuleLayer> layers(ClassLoader loader) { 2264 return ModuleLayer.layers(loader); 2265 } 2266 2267 public String newStringNoRepl(byte[] bytes, Charset cs) throws CharacterCodingException { 2268 return StringCoding.newStringNoRepl(bytes, cs); 2269 } 2270 2271 public byte[] getBytesNoRepl(String s, Charset cs) throws CharacterCodingException { 2272 return StringCoding.getBytesNoRepl(s, cs); 2273 } 2274 2275 public String newStringUTF8NoRepl(byte[] bytes, int off, int len) { 2276 return StringCoding.newStringUTF8NoRepl(bytes, off, len); 2277 } 2278 2279 public byte[] getBytesUTF8NoRepl(String s) { 2280 return StringCoding.getBytesUTF8NoRepl(s); 2281 } 2282 2283 public void setCause(Throwable t, Throwable cause) { 2284 t.setCause(cause); 2285 } 2286 2287 public void loadLibrary(Class<?> caller, String library) { 2288 assert library.indexOf(java.io.File.separatorChar) < 0; 2289 ClassLoader.loadLibrary(caller, library, false); 2290 } 2291 2292 public ProtectionDomain protectionDomain(Class<?> c) { 2293 return c.protectionDomain(); 2294 } 2295 2296 public MethodHandle stringConcatHelper(String name, MethodType methodType) { 2297 return StringConcatHelper.lookupStatic(name, methodType); 2298 } 2299 2300 }); 2301 } 2302 }