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