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