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.List;
53 import java.util.Map;
54 import java.util.Objects;
55 import java.util.Properties;
56 import java.util.PropertyPermission;
57 import java.util.ResourceBundle;
58 import java.util.Set;
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.
588 *
589 * See {@linkplain #getProperties getProperties} for details.
590 */
591 private static Properties props;
592
593 /**
594 * Determines the current system properties.
595 *
596 * First, if there is a security manager, its
597 * {@code checkPropertiesAccess} method is called with no
598 * arguments. This may result in a security exception.
599 * <p>
600 * The current set of system properties for use by the
601 * {@link #getProperty(String)} method is returned as a
602 * {@code Properties} object. If there is no current set of
603 * system properties, a set of system properties is first created and
604 * initialized. This set of system properties includes a value
605 * for each of the following keys unless the description of the associated
606 * value indicates that the value is optional.
607 * <table class="striped" style="text-align:left">
608 * <caption style="display:none">Shows property keys and associated values</caption>
609 * <thead>
610 * <tr><th scope="col">Key</th>
611 * <th scope="col">Description of Associated Value</th></tr>
612 * </thead>
613 * <tbody>
614 * <tr><th scope="row">{@systemProperty java.version}</th>
615 * <td>Java Runtime Environment version, which may be interpreted
616 * as a {@link Runtime.Version}</td></tr>
617 * <tr><th scope="row">{@systemProperty java.version.date}</th>
618 * <td>Java Runtime Environment version date, in ISO-8601 YYYY-MM-DD
619 * format, which may be interpreted as a {@link
620 * java.time.LocalDate}</td></tr>
621 * <tr><th scope="row">{@systemProperty java.vendor}</th>
622 * <td>Java Runtime Environment vendor</td></tr>
623 * <tr><th scope="row">{@systemProperty java.vendor.url}</th>
624 * <td>Java vendor URL</td></tr>
625 * <tr><th scope="row">{@systemProperty java.vendor.version}</th>
626 * <td>Java vendor version <em>(optional)</em> </td></tr>
627 * <tr><th scope="row">{@systemProperty java.home}</th>
628 * <td>Java installation directory</td></tr>
629 * <tr><th scope="row">{@systemProperty java.vm.specification.version}</th>
630 * <td>Java Virtual Machine specification version, whose value is the
631 * {@linkplain Runtime.Version#feature feature} element of the
632 * {@linkplain Runtime#version() runtime version}</td></tr>
633 * <tr><th scope="row">{@systemProperty java.vm.specification.vendor}</th>
634 * <td>Java Virtual Machine specification vendor</td></tr>
635 * <tr><th scope="row">{@systemProperty java.vm.specification.name}</th>
636 * <td>Java Virtual Machine specification name</td></tr>
637 * <tr><th scope="row">{@systemProperty java.vm.version}</th>
638 * <td>Java Virtual Machine implementation version which may be
639 * interpreted as a {@link Runtime.Version}</td></tr>
640 * <tr><th scope="row">{@systemProperty java.vm.vendor}</th>
641 * <td>Java Virtual Machine implementation vendor</td></tr>
642 * <tr><th scope="row">{@systemProperty java.vm.name}</th>
643 * <td>Java Virtual Machine implementation name</td></tr>
644 * <tr><th scope="row">{@systemProperty java.specification.version}</th>
645 * <td>Java Runtime Environment specification version, whose value is
646 * the {@linkplain Runtime.Version#feature feature} element of the
647 * {@linkplain Runtime#version() runtime version}</td></tr>
648 * <tr><th scope="row">{@systemProperty java.specification.vendor}</th>
649 * <td>Java Runtime Environment specification vendor</td></tr>
650 * <tr><th scope="row">{@systemProperty java.specification.name}</th>
651 * <td>Java Runtime Environment specification name</td></tr>
652 * <tr><th scope="row">{@systemProperty java.class.version}</th>
653 * <td>Java class format version number</td></tr>
654 * <tr><th scope="row">{@systemProperty java.class.path}</th>
655 * <td>Java class path (refer to
656 * {@link ClassLoader#getSystemClassLoader()} for details)</td></tr>
657 * <tr><th scope="row">{@systemProperty java.library.path}</th>
658 * <td>List of paths to search when loading libraries</td></tr>
659 * <tr><th scope="row">{@systemProperty java.io.tmpdir}</th>
660 * <td>Default temp file path</td></tr>
661 * <tr><th scope="row">{@systemProperty java.compiler}</th>
662 * <td>Name of JIT compiler to use</td></tr>
663 * <tr><th scope="row">{@systemProperty os.name}</th>
664 * <td>Operating system name</td></tr>
665 * <tr><th scope="row">{@systemProperty os.arch}</th>
666 * <td>Operating system architecture</td></tr>
667 * <tr><th scope="row">{@systemProperty os.version}</th>
668 * <td>Operating system version</td></tr>
669 * <tr><th scope="row">{@systemProperty file.separator}</th>
670 * <td>File separator ("/" on UNIX)</td></tr>
671 * <tr><th scope="row">{@systemProperty path.separator}</th>
672 * <td>Path separator (":" on UNIX)</td></tr>
673 * <tr><th scope="row">{@systemProperty line.separator}</th>
674 * <td>Line separator ("\n" on UNIX)</td></tr>
675 * <tr><th scope="row">{@systemProperty user.name}</th>
676 * <td>User's account name</td></tr>
677 * <tr><th scope="row">{@systemProperty user.home}</th>
678 * <td>User's home directory</td></tr>
679 * <tr><th scope="row">{@systemProperty user.dir}</th>
680 * <td>User's current working directory</td></tr>
681 * </tbody>
682 * </table>
683 * <p>
684 * Multiple paths in a system property value are separated by the path
685 * separator character of the platform.
686 * <p>
687 * Note that even if the security manager does not permit the
688 * {@code getProperties} operation, it may choose to permit the
689 * {@link #getProperty(String)} operation.
690 *
691 * @apiNote
692 * <strong>Changing a standard system property may have unpredictable results
693 * unless otherwise specified.</strong>
694 * Property values may be cached during initialization or on first use.
695 * Setting a standard property after initialization using {@link #getProperties()},
696 * {@link #setProperties(Properties)}, {@link #setProperty(String, String)}, or
697 * {@link #clearProperty(String)} may not have the desired effect.
698 *
699 * @implNote
700 * In addition to the standard system properties, the system
701 * properties may include the following keys:
702 * <table class="striped">
703 * <caption style="display:none">Shows property keys and associated values</caption>
704 * <thead>
705 * <tr><th scope="col">Key</th>
706 * <th scope="col">Description of Associated Value</th></tr>
707 * </thead>
708 * <tbody>
709 * <tr><th scope="row">{@systemProperty jdk.module.path}</th>
710 * <td>The application module path</td></tr>
711 * <tr><th scope="row">{@systemProperty jdk.module.upgrade.path}</th>
712 * <td>The upgrade module path</td></tr>
713 * <tr><th scope="row">{@systemProperty jdk.module.main}</th>
714 * <td>The module name of the initial/main module</td></tr>
715 * <tr><th scope="row">{@systemProperty jdk.module.main.class}</th>
716 * <td>The main class name of the initial module</td></tr>
717 * </tbody>
718 * </table>
719 *
720 * @return the system properties
721 * @throws SecurityException if a security manager exists and its
722 * {@code checkPropertiesAccess} method doesn't allow access
723 * to the system properties.
724 * @see #setProperties
725 * @see java.lang.SecurityException
726 * @see java.lang.SecurityManager#checkPropertiesAccess()
727 * @see java.util.Properties
728 */
729 public static Properties getProperties() {
730 SecurityManager sm = getSecurityManager();
731 if (sm != null) {
732 sm.checkPropertiesAccess();
733 }
734
735 return props;
736 }
737
738 /**
739 * Returns the system-dependent line separator string. It always
740 * returns the same value - the initial value of the {@linkplain
741 * #getProperty(String) system property} {@code line.separator}.
742 *
743 * <p>On UNIX systems, it returns {@code "\n"}; on Microsoft
744 * Windows systems it returns {@code "\r\n"}.
745 *
746 * @return the system-dependent line separator string
747 * @since 1.7
748 */
749 public static String lineSeparator() {
750 return lineSeparator;
751 }
752
753 private static String lineSeparator;
754
755 /**
756 * Sets the system properties to the {@code Properties} argument.
757 *
758 * First, if there is a security manager, its
759 * {@code checkPropertiesAccess} method is called with no
760 * arguments. This may result in a security exception.
761 * <p>
762 * The argument becomes the current set of system properties for use
763 * by the {@link #getProperty(String)} method. If the argument is
764 * {@code null}, then the current set of system properties is
765 * forgotten.
766 *
767 * @apiNote
768 * <strong>Changing a standard system property may have unpredictable results
769 * unless otherwise specified</strong>.
770 * See {@linkplain #getProperties getProperties} for details.
771 *
772 * @param props the new system properties.
773 * @throws SecurityException if a security manager exists and its
774 * {@code checkPropertiesAccess} method doesn't allow access
775 * to the system properties.
776 * @see #getProperties
777 * @see java.util.Properties
778 * @see java.lang.SecurityException
779 * @see java.lang.SecurityManager#checkPropertiesAccess()
780 */
781 public static void setProperties(Properties props) {
782 SecurityManager sm = getSecurityManager();
783 if (sm != null) {
784 sm.checkPropertiesAccess();
785 }
786
787 if (props == null) {
788 Map<String, String> tempProps = SystemProps.initProperties();
789 VersionProps.init(tempProps);
790 props = createProperties(tempProps);
791 }
792 System.props = props;
793 }
794
795 /**
796 * Gets the system property indicated by the specified key.
797 *
798 * First, if there is a security manager, its
799 * {@code checkPropertyAccess} method is called with the key as
800 * its argument. This may result in a SecurityException.
801 * <p>
802 * If there is no current set of system properties, a set of system
803 * properties is first created and initialized in the same manner as
804 * for the {@code getProperties} method.
805 *
806 * @apiNote
807 * <strong>Changing a standard system property may have unpredictable results
808 * unless otherwise specified</strong>.
809 * See {@linkplain #getProperties getProperties} for details.
810 *
811 * @param key the name of the system property.
812 * @return the string value of the system property,
813 * or {@code null} if there is no property with that key.
814 *
815 * @throws SecurityException if a security manager exists and its
816 * {@code checkPropertyAccess} method doesn't allow
817 * access to the specified system property.
818 * @throws NullPointerException if {@code key} is {@code null}.
819 * @throws IllegalArgumentException if {@code key} is empty.
820 * @see #setProperty
821 * @see java.lang.SecurityException
822 * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
823 * @see java.lang.System#getProperties()
824 */
825 public static String getProperty(String key) {
826 checkKey(key);
827 SecurityManager sm = getSecurityManager();
828 if (sm != null) {
829 sm.checkPropertyAccess(key);
830 }
831
832 return props.getProperty(key);
833 }
834
835 /**
836 * Gets the system property indicated by the specified key.
837 *
838 * First, if there is a security manager, its
839 * {@code checkPropertyAccess} method is called with the
840 * {@code key} as its argument.
841 * <p>
842 * If there is no current set of system properties, a set of system
843 * properties is first created and initialized in the same manner as
844 * for the {@code getProperties} method.
845 *
846 * @param key the name of the system property.
847 * @param def a default value.
848 * @return the string value of the system property,
849 * or the default value if there is no property with that key.
850 *
851 * @throws SecurityException if a security manager exists and its
852 * {@code checkPropertyAccess} method doesn't allow
853 * access to the specified system property.
854 * @throws NullPointerException if {@code key} is {@code null}.
855 * @throws IllegalArgumentException if {@code key} is empty.
856 * @see #setProperty
857 * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
858 * @see java.lang.System#getProperties()
859 */
860 public static String getProperty(String key, String def) {
861 checkKey(key);
862 SecurityManager sm = getSecurityManager();
863 if (sm != null) {
864 sm.checkPropertyAccess(key);
865 }
866
867 return props.getProperty(key, def);
868 }
869
870 /**
871 * Sets the system property indicated by the specified key.
872 *
873 * First, if a security manager exists, its
874 * {@code SecurityManager.checkPermission} method
875 * is called with a {@code PropertyPermission(key, "write")}
876 * permission. This may result in a SecurityException being thrown.
877 * If no exception is thrown, the specified property is set to the given
878 * value.
879 *
880 * @apiNote
881 * <strong>Changing a standard system property may have unpredictable results
882 * unless otherwise specified</strong>.
883 * See {@linkplain #getProperties getProperties} for details.
884 *
885 * @param key the name of the system property.
886 * @param value the value of the system property.
887 * @return the previous value of the system property,
888 * or {@code null} if it did not have one.
889 *
890 * @throws SecurityException if a security manager exists and its
891 * {@code checkPermission} method doesn't allow
892 * setting of the specified property.
893 * @throws NullPointerException if {@code key} or
894 * {@code value} is {@code null}.
895 * @throws IllegalArgumentException if {@code key} is empty.
896 * @see #getProperty
897 * @see java.lang.System#getProperty(java.lang.String)
898 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
899 * @see java.util.PropertyPermission
900 * @see SecurityManager#checkPermission
901 * @since 1.2
902 */
903 public static String setProperty(String key, String value) {
904 checkKey(key);
905 SecurityManager sm = getSecurityManager();
906 if (sm != null) {
907 sm.checkPermission(new PropertyPermission(key,
908 SecurityConstants.PROPERTY_WRITE_ACTION));
909 }
910
911 return (String) props.setProperty(key, value);
912 }
913
914 /**
915 * Removes the system property indicated by the specified key.
916 *
917 * First, if a security manager exists, its
918 * {@code SecurityManager.checkPermission} method
919 * is called with a {@code PropertyPermission(key, "write")}
920 * permission. This may result in a SecurityException being thrown.
921 * If no exception is thrown, the specified property is removed.
922 *
923 * @apiNote
924 * <strong>Changing a standard system property may have unpredictable results
925 * unless otherwise specified</strong>.
926 * See {@linkplain #getProperties getProperties} method for details.
927 *
928 * @param key the name of the system property to be removed.
929 * @return the previous string value of the system property,
930 * or {@code null} if there was no property with that key.
931 *
932 * @throws SecurityException if a security manager exists and its
933 * {@code checkPropertyAccess} method doesn't allow
934 * access to the specified system property.
935 * @throws NullPointerException if {@code key} is {@code null}.
936 * @throws IllegalArgumentException if {@code key} is empty.
937 * @see #getProperty
938 * @see #setProperty
939 * @see java.util.Properties
940 * @see java.lang.SecurityException
941 * @see java.lang.SecurityManager#checkPropertiesAccess()
942 * @since 1.5
943 */
944 public static String clearProperty(String key) {
945 checkKey(key);
946 SecurityManager sm = getSecurityManager();
947 if (sm != null) {
948 sm.checkPermission(new PropertyPermission(key, "write"));
949 }
950
951 return (String) props.remove(key);
952 }
953
954 private static void checkKey(String key) {
955 if (key == null) {
956 throw new NullPointerException("key can't be null");
957 }
958 if (key.isEmpty()) {
959 throw new IllegalArgumentException("key can't be empty");
960 }
961 }
962
963 /**
964 * Gets the value of the specified environment variable. An
965 * environment variable is a system-dependent external named
966 * value.
967 *
968 * <p>If a security manager exists, its
969 * {@link SecurityManager#checkPermission checkPermission}
970 * method is called with a
971 * {@link RuntimePermission RuntimePermission("getenv."+name)}
972 * permission. This may result in a {@link SecurityException}
973 * being thrown. If no exception is thrown the value of the
974 * variable {@code name} is returned.
975 *
976 * <p><a id="EnvironmentVSSystemProperties"><i>System
977 * properties</i> and <i>environment variables</i></a> are both
978 * conceptually mappings between names and values. Both
979 * mechanisms can be used to pass user-defined information to a
980 * Java process. Environment variables have a more global effect,
981 * because they are visible to all descendants of the process
982 * which defines them, not just the immediate Java subprocess.
983 * They can have subtly different semantics, such as case
984 * insensitivity, on different operating systems. For these
985 * reasons, environment variables are more likely to have
986 * unintended side effects. It is best to use system properties
987 * where possible. Environment variables should be used when a
988 * global effect is desired, or when an external system interface
989 * requires an environment variable (such as {@code PATH}).
990 *
991 * <p>On UNIX systems the alphabetic case of {@code name} is
992 * typically significant, while on Microsoft Windows systems it is
993 * typically not. For example, the expression
994 * {@code System.getenv("FOO").equals(System.getenv("foo"))}
995 * is likely to be true on Microsoft Windows.
996 *
997 * @param name the name of the environment variable
998 * @return the string value of the variable, or {@code null}
999 * if the variable is not defined in the system environment
1000 * @throws NullPointerException if {@code name} is {@code null}
1001 * @throws SecurityException
1002 * if a security manager exists and its
1003 * {@link SecurityManager#checkPermission checkPermission}
1004 * method doesn't allow access to the environment variable
1005 * {@code name}
1006 * @see #getenv()
1007 * @see ProcessBuilder#environment()
1008 */
1009 public static String getenv(String name) {
1010 SecurityManager sm = getSecurityManager();
1011 if (sm != null) {
1012 sm.checkPermission(new RuntimePermission("getenv."+name));
1013 }
1014
1015 return ProcessEnvironment.getenv(name);
1016 }
1017
1018
1019 /**
1020 * Returns an unmodifiable string map view of the current system environment.
1021 * The environment is a system-dependent mapping from names to
1022 * values which is passed from parent to child processes.
1023 *
1024 * <p>If the system does not support environment variables, an
1025 * empty map is returned.
1026 *
1027 * <p>The returned map will never contain null keys or values.
1028 * Attempting to query the presence of a null key or value will
1029 * throw a {@link NullPointerException}. Attempting to query
1030 * the presence of a key or value which is not of type
1031 * {@link String} will throw a {@link ClassCastException}.
1032 *
1033 * <p>The returned map and its collection views may not obey the
1034 * general contract of the {@link Object#equals} and
1035 * {@link Object#hashCode} methods.
1036 *
1037 * <p>The returned map is typically case-sensitive on all platforms.
1038 *
1039 * <p>If a security manager exists, its
1040 * {@link SecurityManager#checkPermission checkPermission}
1041 * method is called with a
1042 * {@link RuntimePermission RuntimePermission("getenv.*")} permission.
1043 * This may result in a {@link SecurityException} being thrown.
1044 *
1045 * <p>When passing information to a Java subprocess,
1046 * <a href=#EnvironmentVSSystemProperties>system properties</a>
1047 * are generally preferred over environment variables.
1048 *
1049 * @return the environment as a map of variable names to values
1050 * @throws SecurityException
1051 * if a security manager exists and its
1052 * {@link SecurityManager#checkPermission checkPermission}
1053 * method doesn't allow access to the process environment
1054 * @see #getenv(String)
1055 * @see ProcessBuilder#environment()
1056 * @since 1.5
1057 */
1058 public static java.util.Map<String,String> getenv() {
1059 SecurityManager sm = getSecurityManager();
1060 if (sm != null) {
1061 sm.checkPermission(new RuntimePermission("getenv.*"));
1062 }
1063
1064 return ProcessEnvironment.getenv();
1065 }
1066
1067 /**
1068 * {@code System.Logger} instances log messages that will be
1069 * routed to the underlying logging framework the {@link System.LoggerFinder
1070 * LoggerFinder} uses.
1071 *
1072 * {@code System.Logger} instances are typically obtained from
1073 * the {@link java.lang.System System} class, by calling
1074 * {@link java.lang.System#getLogger(java.lang.String) System.getLogger(loggerName)}
1075 * or {@link java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
1076 * System.getLogger(loggerName, bundle)}.
1077 *
1078 * @see java.lang.System#getLogger(java.lang.String)
1079 * @see java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
1080 * @see java.lang.System.LoggerFinder
1081 *
1082 * @since 9
1083 */
1084 public interface Logger {
1085
1086 /**
1087 * System {@linkplain Logger loggers} levels.
1088 *
1089 * A level has a {@linkplain #getName() name} and {@linkplain
1090 * #getSeverity() severity}.
1091 * Level values are {@link #ALL}, {@link #TRACE}, {@link #DEBUG},
1092 * {@link #INFO}, {@link #WARNING}, {@link #ERROR}, {@link #OFF},
1093 * by order of increasing severity.
1094 * <br>
1095 * {@link #ALL} and {@link #OFF}
1096 * are simple markers with severities mapped respectively to
1097 * {@link java.lang.Integer#MIN_VALUE Integer.MIN_VALUE} and
1098 * {@link java.lang.Integer#MAX_VALUE Integer.MAX_VALUE}.
1099 * <p>
1100 * <b>Severity values and Mapping to {@code java.util.logging.Level}.</b>
1101 * <p>
1102 * {@linkplain System.Logger.Level System logger levels} are mapped to
1103 * {@linkplain java.util.logging.Level java.util.logging levels}
1104 * of corresponding severity.
1105 * <br>The mapping is as follows:
1106 * <br><br>
1107 * <table class="striped">
1108 * <caption>System.Logger Severity Level Mapping</caption>
1109 * <thead>
1110 * <tr><th scope="col">System.Logger Levels</th>
1111 * <th scope="col">java.util.logging Levels</th>
1112 * </thead>
1113 * <tbody>
1114 * <tr><th scope="row">{@link Logger.Level#ALL ALL}</th>
1115 * <td>{@link java.util.logging.Level#ALL ALL}</td>
1116 * <tr><th scope="row">{@link Logger.Level#TRACE TRACE}</th>
1117 * <td>{@link java.util.logging.Level#FINER FINER}</td>
1118 * <tr><th scope="row">{@link Logger.Level#DEBUG DEBUG}</th>
1119 * <td>{@link java.util.logging.Level#FINE FINE}</td>
1120 * <tr><th scope="row">{@link Logger.Level#INFO INFO}</th>
1121 * <td>{@link java.util.logging.Level#INFO INFO}</td>
1122 * <tr><th scope="row">{@link Logger.Level#WARNING WARNING}</th>
1123 * <td>{@link java.util.logging.Level#WARNING WARNING}</td>
1124 * <tr><th scope="row">{@link Logger.Level#ERROR ERROR}</th>
1125 * <td>{@link java.util.logging.Level#SEVERE SEVERE}</td>
1126 * <tr><th scope="row">{@link Logger.Level#OFF OFF}</th>
1127 * <td>{@link java.util.logging.Level#OFF OFF}</td>
1128 * </tbody>
1129 * </table>
1130 *
1131 * @since 9
1132 *
1133 * @see java.lang.System.LoggerFinder
1134 * @see java.lang.System.Logger
1135 */
1136 public enum Level {
1137
1138 // for convenience, we're reusing java.util.logging.Level int values
1139 // the mapping logic in sun.util.logging.PlatformLogger depends
1140 // on this.
1141 /**
1142 * A marker to indicate that all levels are enabled.
1143 * This level {@linkplain #getSeverity() severity} is
1144 * {@link Integer#MIN_VALUE}.
1145 */
1146 ALL(Integer.MIN_VALUE), // typically mapped to/from j.u.l.Level.ALL
1147 /**
1148 * {@code TRACE} level: usually used to log diagnostic information.
1149 * This level {@linkplain #getSeverity() severity} is
1150 * {@code 400}.
1151 */
1152 TRACE(400), // typically mapped to/from j.u.l.Level.FINER
1153 /**
1154 * {@code DEBUG} level: usually used to log debug information traces.
1155 * This level {@linkplain #getSeverity() severity} is
1156 * {@code 500}.
1157 */
1158 DEBUG(500), // typically mapped to/from j.u.l.Level.FINEST/FINE/CONFIG
1159 /**
1160 * {@code INFO} level: usually used to log information messages.
1161 * This level {@linkplain #getSeverity() severity} is
1162 * {@code 800}.
1163 */
1164 INFO(800), // typically mapped to/from j.u.l.Level.INFO
1165 /**
1166 * {@code WARNING} level: usually used to log warning messages.
1167 * This level {@linkplain #getSeverity() severity} is
1168 * {@code 900}.
1169 */
1170 WARNING(900), // typically mapped to/from j.u.l.Level.WARNING
1171 /**
1172 * {@code ERROR} level: usually used to log error messages.
1173 * This level {@linkplain #getSeverity() severity} is
1174 * {@code 1000}.
1175 */
1176 ERROR(1000), // typically mapped to/from j.u.l.Level.SEVERE
1177 /**
1178 * A marker to indicate that all levels are disabled.
1179 * This level {@linkplain #getSeverity() severity} is
1180 * {@link Integer#MAX_VALUE}.
1181 */
1182 OFF(Integer.MAX_VALUE); // typically mapped to/from j.u.l.Level.OFF
1183
1184 private final int severity;
1185
1186 private Level(int severity) {
1187 this.severity = severity;
1188 }
1189
1190 /**
1191 * Returns the name of this level.
1192 * @return this level {@linkplain #name()}.
1193 */
1194 public final String getName() {
1195 return name();
1196 }
1197
1198 /**
1199 * Returns the severity of this level.
1200 * A higher severity means a more severe condition.
1201 * @return this level severity.
1202 */
1203 public final int getSeverity() {
1204 return severity;
1205 }
1206 }
1207
1208 /**
1209 * Returns the name of this logger.
1210 *
1211 * @return the logger name.
1212 */
1213 public String getName();
1214
1215 /**
1216 * Checks if a message of the given level would be logged by
1217 * this logger.
1218 *
1219 * @param level the log message level.
1220 * @return {@code true} if the given log message level is currently
1221 * being logged.
1222 *
1223 * @throws NullPointerException if {@code level} is {@code null}.
1224 */
1225 public boolean isLoggable(Level level);
1226
1227 /**
1228 * Logs a message.
1229 *
1230 * @implSpec The default implementation for this method calls
1231 * {@code this.log(level, (ResourceBundle)null, msg, (Object[])null);}
1232 *
1233 * @param level the log message level.
1234 * @param msg the string message (or a key in the message catalog, if
1235 * this logger is a {@link
1236 * LoggerFinder#getLocalizedLogger(java.lang.String,
1237 * java.util.ResourceBundle, java.lang.Module) localized logger});
1238 * can be {@code null}.
1239 *
1240 * @throws NullPointerException if {@code level} is {@code null}.
1241 */
1242 public default void log(Level level, String msg) {
1243 log(level, (ResourceBundle) null, msg, (Object[]) null);
1244 }
1245
1246 /**
1247 * Logs a lazily supplied message.
1248 *
1249 * If the logger is currently enabled for the given log message level
1250 * then a message is logged that is the result produced by the
1251 * given supplier function. Otherwise, the supplier is not operated on.
1252 *
1253 * @implSpec When logging is enabled for the given level, the default
1254 * implementation for this method calls
1255 * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), (Object[])null);}
1256 *
1257 * @param level the log message level.
1258 * @param msgSupplier a supplier function that produces a message.
1259 *
1260 * @throws NullPointerException if {@code level} is {@code null},
1261 * or {@code msgSupplier} is {@code null}.
1262 */
1263 public default void log(Level level, Supplier<String> msgSupplier) {
1264 Objects.requireNonNull(msgSupplier);
1265 if (isLoggable(Objects.requireNonNull(level))) {
1266 log(level, (ResourceBundle) null, msgSupplier.get(), (Object[]) null);
1267 }
1268 }
1269
1270 /**
1271 * Logs a message produced from the given object.
1272 *
1273 * If the logger is currently enabled for the given log message level then
1274 * a message is logged that, by default, is the result produced from
1275 * calling toString on the given object.
1276 * Otherwise, the object is not operated on.
1277 *
1278 * @implSpec When logging is enabled for the given level, the default
1279 * implementation for this method calls
1280 * {@code this.log(level, (ResourceBundle)null, obj.toString(), (Object[])null);}
1281 *
1282 * @param level the log message level.
1283 * @param obj the object to log.
1284 *
1285 * @throws NullPointerException if {@code level} is {@code null}, or
1286 * {@code obj} is {@code null}.
1287 */
1288 public default void log(Level level, Object obj) {
1289 Objects.requireNonNull(obj);
1290 if (isLoggable(Objects.requireNonNull(level))) {
1291 this.log(level, (ResourceBundle) null, obj.toString(), (Object[]) null);
1292 }
1293 }
1294
1295 /**
1296 * Logs a message associated with a given throwable.
1297 *
1298 * @implSpec The default implementation for this method calls
1299 * {@code this.log(level, (ResourceBundle)null, msg, thrown);}
1300 *
1301 * @param level the log message level.
1302 * @param msg the string message (or a key in the message catalog, if
1303 * this logger is a {@link
1304 * LoggerFinder#getLocalizedLogger(java.lang.String,
1305 * java.util.ResourceBundle, java.lang.Module) localized logger});
1306 * can be {@code null}.
1307 * @param thrown a {@code Throwable} associated with the log message;
1308 * can be {@code null}.
1309 *
1310 * @throws NullPointerException if {@code level} is {@code null}.
1311 */
1312 public default void log(Level level, String msg, Throwable thrown) {
1313 this.log(level, null, msg, thrown);
1314 }
1315
1316 /**
1317 * Logs a lazily supplied message associated with a given throwable.
1318 *
1319 * If the logger is currently enabled for the given log message level
1320 * then a message is logged that is the result produced by the
1321 * given supplier function. Otherwise, the supplier is not operated on.
1322 *
1323 * @implSpec When logging is enabled for the given level, the default
1324 * implementation for this method calls
1325 * {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), thrown);}
1326 *
1327 * @param level one of the log message level identifiers.
1328 * @param msgSupplier a supplier function that produces a message.
1329 * @param thrown a {@code Throwable} associated with log message;
1330 * can be {@code null}.
1331 *
1332 * @throws NullPointerException if {@code level} is {@code null}, or
1333 * {@code msgSupplier} is {@code null}.
1334 */
1335 public default void log(Level level, Supplier<String> msgSupplier,
1336 Throwable thrown) {
1337 Objects.requireNonNull(msgSupplier);
1338 if (isLoggable(Objects.requireNonNull(level))) {
1339 this.log(level, null, msgSupplier.get(), thrown);
1340 }
1341 }
1342
1343 /**
1344 * Logs a message with an optional list of parameters.
1345 *
1346 * @implSpec The default implementation for this method calls
1347 * {@code this.log(level, (ResourceBundle)null, format, params);}
1348 *
1349 * @param level one of the log message level identifiers.
1350 * @param format the string message format in {@link
1351 * java.text.MessageFormat} format, (or a key in the message
1352 * catalog, if this logger is a {@link
1353 * LoggerFinder#getLocalizedLogger(java.lang.String,
1354 * java.util.ResourceBundle, java.lang.Module) localized logger});
1355 * can be {@code null}.
1356 * @param params an optional list of parameters to the message (may be
1357 * none).
1358 *
1359 * @throws NullPointerException if {@code level} is {@code null}.
1360 */
1361 public default void log(Level level, String format, Object... params) {
1362 this.log(level, null, format, params);
1363 }
1364
1365 /**
1366 * Logs a localized message associated with a given throwable.
1367 *
1368 * If the given resource bundle is non-{@code null}, the {@code msg}
1369 * string is localized using the given resource bundle.
1370 * Otherwise the {@code msg} string is not localized.
1371 *
1372 * @param level the log message level.
1373 * @param bundle a resource bundle to localize {@code msg}; can be
1374 * {@code null}.
1375 * @param msg the string message (or a key in the message catalog,
1376 * if {@code bundle} is not {@code null}); can be {@code null}.
1377 * @param thrown a {@code Throwable} associated with the log message;
1378 * can be {@code null}.
1379 *
1380 * @throws NullPointerException if {@code level} is {@code null}.
1381 */
1382 public void log(Level level, ResourceBundle bundle, String msg,
1383 Throwable thrown);
1384
1385 /**
1386 * Logs a message with resource bundle and an optional list of
1387 * parameters.
1388 *
1389 * If the given resource bundle is non-{@code null}, the {@code format}
1390 * string is localized using the given resource bundle.
1391 * Otherwise the {@code format} string is not localized.
1392 *
1393 * @param level the log message level.
1394 * @param bundle a resource bundle to localize {@code format}; can be
1395 * {@code null}.
1396 * @param format the string message format in {@link
1397 * java.text.MessageFormat} format, (or a key in the message
1398 * catalog if {@code bundle} is not {@code null}); can be {@code null}.
1399 * @param params an optional list of parameters to the message (may be
1400 * none).
1401 *
1402 * @throws NullPointerException if {@code level} is {@code null}.
1403 */
1404 public void log(Level level, ResourceBundle bundle, String format,
1405 Object... params);
1406 }
1407
1408 /**
1409 * The {@code LoggerFinder} service is responsible for creating, managing,
1410 * and configuring loggers to the underlying framework it uses.
1411 *
1412 * A logger finder is a concrete implementation of this class that has a
1413 * zero-argument constructor and implements the abstract methods defined
1414 * by this class.
1415 * The loggers returned from a logger finder are capable of routing log
1416 * messages to the logging backend this provider supports.
1417 * A given invocation of the Java Runtime maintains a single
1418 * system-wide LoggerFinder instance that is loaded as follows:
1419 * <ul>
1420 * <li>First it finds any custom {@code LoggerFinder} provider
1421 * using the {@link java.util.ServiceLoader} facility with the
1422 * {@linkplain ClassLoader#getSystemClassLoader() system class
1423 * loader}.</li>
1424 * <li>If no {@code LoggerFinder} provider is found, the system default
1425 * {@code LoggerFinder} implementation will be used.</li>
1426 * </ul>
1427 * <p>
1428 * An application can replace the logging backend
1429 * <i>even when the java.logging module is present</i>, by simply providing
1430 * and declaring an implementation of the {@link LoggerFinder} service.
1431 * <p>
1432 * <b>Default Implementation</b>
1433 * <p>
1434 * The system default {@code LoggerFinder} implementation uses
1435 * {@code java.util.logging} as the backend framework when the
1436 * {@code java.logging} module is present.
1437 * It returns a {@linkplain System.Logger logger} instance
1438 * that will route log messages to a {@link java.util.logging.Logger
1439 * java.util.logging.Logger}. Otherwise, if {@code java.logging} is not
1440 * present, the default implementation will return a simple logger
1441 * instance that will route log messages of {@code INFO} level and above to
1442 * the console ({@code System.err}).
1443 * <p>
1444 * <b>Logging Configuration</b>
1445 * <p>
1446 * {@linkplain Logger Logger} instances obtained from the
1447 * {@code LoggerFinder} factory methods are not directly configurable by
1448 * the application. Configuration is the responsibility of the underlying
1449 * logging backend, and usually requires using APIs specific to that backend.
1450 * <p>For the default {@code LoggerFinder} implementation
1451 * using {@code java.util.logging} as its backend, refer to
1452 * {@link java.util.logging java.util.logging} for logging configuration.
1453 * For the default {@code LoggerFinder} implementation returning simple loggers
1454 * when the {@code java.logging} module is absent, the configuration
1455 * is implementation dependent.
1456 * <p>
1457 * Usually an application that uses a logging framework will log messages
1458 * through a logger facade defined (or supported) by that framework.
1459 * Applications that wish to use an external framework should log
1460 * through the facade associated with that framework.
1461 * <p>
1462 * A system class that needs to log messages will typically obtain
1463 * a {@link System.Logger} instance to route messages to the logging
1464 * framework selected by the application.
1465 * <p>
1466 * Libraries and classes that only need loggers to produce log messages
1467 * should not attempt to configure loggers by themselves, as that
1468 * would make them dependent from a specific implementation of the
1469 * {@code LoggerFinder} service.
1470 * <p>
1471 * In addition, when a security manager is present, loggers provided to
1472 * system classes should not be directly configurable through the logging
1473 * backend without requiring permissions.
1474 * <br>
1475 * It is the responsibility of the provider of
1476 * the concrete {@code LoggerFinder} implementation to ensure that
1477 * these loggers are not configured by untrusted code without proper
1478 * permission checks, as configuration performed on such loggers usually
1479 * affects all applications in the same Java Runtime.
1480 * <p>
1481 * <b>Message Levels and Mapping to backend levels</b>
1482 * <p>
1483 * A logger finder is responsible for mapping from a {@code
1484 * System.Logger.Level} to a level supported by the logging backend it uses.
1485 * <br>The default LoggerFinder using {@code java.util.logging} as the backend
1486 * maps {@code System.Logger} levels to
1487 * {@linkplain java.util.logging.Level java.util.logging} levels
1488 * of corresponding severity - as described in {@link Logger.Level
1489 * Logger.Level}.
1490 *
1491 * @see java.lang.System
1492 * @see java.lang.System.Logger
1493 *
1494 * @since 9
1495 */
1496 public static abstract class LoggerFinder {
1497 /**
1498 * The {@code RuntimePermission("loggerFinder")} is
1499 * necessary to subclass and instantiate the {@code LoggerFinder} class,
1500 * as well as to obtain loggers from an instance of that class.
1501 */
1502 static final RuntimePermission LOGGERFINDER_PERMISSION =
1503 new RuntimePermission("loggerFinder");
1504
1505 /**
1506 * Creates a new instance of {@code LoggerFinder}.
1507 *
1508 * @implNote It is recommended that a {@code LoggerFinder} service
1509 * implementation does not perform any heavy initialization in its
1510 * constructor, in order to avoid possible risks of deadlock or class
1511 * loading cycles during the instantiation of the service provider.
1512 *
1513 * @throws SecurityException if a security manager is present and its
1514 * {@code checkPermission} method doesn't allow the
1515 * {@code RuntimePermission("loggerFinder")}.
1516 */
1517 protected LoggerFinder() {
1518 this(checkPermission());
1519 }
1520
1521 private LoggerFinder(Void unused) {
1522 // nothing to do.
1523 }
1524
1525 private static Void checkPermission() {
1526 final SecurityManager sm = System.getSecurityManager();
1527 if (sm != null) {
1528 sm.checkPermission(LOGGERFINDER_PERMISSION);
1529 }
1530 return null;
1531 }
1532
1533 /**
1534 * Returns an instance of {@link Logger Logger}
1535 * for the given {@code module}.
1536 *
1537 * @param name the name of the logger.
1538 * @param module the module for which the logger is being requested.
1539 *
1540 * @return a {@link Logger logger} suitable for use within the given
1541 * module.
1542 * @throws NullPointerException if {@code name} is {@code null} or
1543 * {@code module} is {@code null}.
1544 * @throws SecurityException if a security manager is present and its
1545 * {@code checkPermission} method doesn't allow the
1546 * {@code RuntimePermission("loggerFinder")}.
1547 */
1548 public abstract Logger getLogger(String name, Module module);
1549
1550 /**
1551 * Returns a localizable instance of {@link Logger Logger}
1552 * for the given {@code module}.
1553 * The returned logger will use the provided resource bundle for
1554 * message localization.
1555 *
1556 * @implSpec By default, this method calls {@link
1557 * #getLogger(java.lang.String, java.lang.Module)
1558 * this.getLogger(name, module)} to obtain a logger, then wraps that
1559 * logger in a {@link Logger} instance where all methods that do not
1560 * take a {@link ResourceBundle} as parameter are redirected to one
1561 * which does - passing the given {@code bundle} for
1562 * localization. So for instance, a call to {@link
1563 * Logger#log(Logger.Level, String) Logger.log(Level.INFO, msg)}
1564 * will end up as a call to {@link
1565 * Logger#log(Logger.Level, ResourceBundle, String, Object...)
1566 * Logger.log(Level.INFO, bundle, msg, (Object[])null)} on the wrapped
1567 * logger instance.
1568 * Note however that by default, string messages returned by {@link
1569 * java.util.function.Supplier Supplier<String>} will not be
1570 * localized, as it is assumed that such strings are messages which are
1571 * already constructed, rather than keys in a resource bundle.
1572 * <p>
1573 * An implementation of {@code LoggerFinder} may override this method,
1574 * for example, when the underlying logging backend provides its own
1575 * mechanism for localizing log messages, then such a
1576 * {@code LoggerFinder} would be free to return a logger
1577 * that makes direct use of the mechanism provided by the backend.
1578 *
1579 * @param name the name of the logger.
1580 * @param bundle a resource bundle; can be {@code null}.
1581 * @param module the module for which the logger is being requested.
1582 * @return an instance of {@link Logger Logger} which will use the
1583 * provided resource bundle for message localization.
1584 *
1585 * @throws NullPointerException if {@code name} is {@code null} or
1586 * {@code module} is {@code null}.
1587 * @throws SecurityException if a security manager is present and its
1588 * {@code checkPermission} method doesn't allow the
1589 * {@code RuntimePermission("loggerFinder")}.
1590 */
1591 public Logger getLocalizedLogger(String name, ResourceBundle bundle,
1592 Module module) {
1593 return new LocalizedLoggerWrapper<>(getLogger(name, module), bundle);
1594 }
1595
1596 /**
1597 * Returns the {@code LoggerFinder} instance. There is one
1598 * single system-wide {@code LoggerFinder} instance in
1599 * the Java Runtime. See the class specification of how the
1600 * {@link LoggerFinder LoggerFinder} implementation is located and
1601 * loaded.
1602 *
1603 * @return the {@link LoggerFinder LoggerFinder} instance.
1604 * @throws SecurityException if a security manager is present and its
1605 * {@code checkPermission} method doesn't allow the
1606 * {@code RuntimePermission("loggerFinder")}.
1607 */
1608 public static LoggerFinder getLoggerFinder() {
1609 final SecurityManager sm = System.getSecurityManager();
1610 if (sm != null) {
1611 sm.checkPermission(LOGGERFINDER_PERMISSION);
1612 }
1613 return accessProvider();
1614 }
1615
1616
1617 private static volatile LoggerFinder service;
1618 static LoggerFinder accessProvider() {
1619 // We do not need to synchronize: LoggerFinderLoader will
1620 // always return the same instance, so if we don't have it,
1621 // just fetch it again.
1622 if (service == null) {
1623 PrivilegedAction<LoggerFinder> pa =
1624 () -> LoggerFinderLoader.getLoggerFinder();
1625 service = AccessController.doPrivileged(pa, null,
1626 LOGGERFINDER_PERMISSION);
1627 }
1628 return service;
1629 }
1630
1631 }
1632
1633
1634 /**
1635 * Returns an instance of {@link Logger Logger} for the caller's
1636 * use.
1637 *
1638 * @implSpec
1639 * Instances returned by this method route messages to loggers
1640 * obtained by calling {@link LoggerFinder#getLogger(java.lang.String,
1641 * java.lang.Module) LoggerFinder.getLogger(name, module)}, where
1642 * {@code module} is the caller's module.
1643 * In cases where {@code System.getLogger} is called from a context where
1644 * there is no caller frame on the stack (e.g when called directly
1645 * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1646 * To obtain a logger in such a context, use an auxiliary class that will
1647 * implicitly be identified as the caller, or use the system {@link
1648 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1649 * Note that doing the latter may eagerly initialize the underlying
1650 * logging system.
1651 *
1652 * @apiNote
1653 * This method may defer calling the {@link
1654 * LoggerFinder#getLogger(java.lang.String, java.lang.Module)
1655 * LoggerFinder.getLogger} method to create an actual logger supplied by
1656 * the logging backend, for instance, to allow loggers to be obtained during
1657 * the system initialization time.
1658 *
1659 * @param name the name of the logger.
1660 * @return an instance of {@link Logger} that can be used by the calling
1661 * class.
1662 * @throws NullPointerException if {@code name} is {@code null}.
1663 * @throws IllegalCallerException if there is no Java caller frame on the
1664 * stack.
1665 *
1666 * @since 9
1667 */
1668 @CallerSensitive
1669 public static Logger getLogger(String name) {
1670 Objects.requireNonNull(name);
1671 final Class<?> caller = Reflection.getCallerClass();
1672 if (caller == null) {
1673 throw new IllegalCallerException("no caller frame");
1674 }
1675 return LazyLoggers.getLogger(name, caller.getModule());
1676 }
1677
1678 /**
1679 * Returns a localizable instance of {@link Logger
1680 * Logger} for the caller's use.
1681 * The returned logger will use the provided resource bundle for message
1682 * localization.
1683 *
1684 * @implSpec
1685 * The returned logger will perform message localization as specified
1686 * by {@link LoggerFinder#getLocalizedLogger(java.lang.String,
1687 * java.util.ResourceBundle, java.lang.Module)
1688 * LoggerFinder.getLocalizedLogger(name, bundle, module)}, where
1689 * {@code module} is the caller's module.
1690 * In cases where {@code System.getLogger} is called from a context where
1691 * there is no caller frame on the stack (e.g when called directly
1692 * from a JNI attached thread), {@code IllegalCallerException} is thrown.
1693 * To obtain a logger in such a context, use an auxiliary class that
1694 * will implicitly be identified as the caller, or use the system {@link
1695 * LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
1696 * Note that doing the latter may eagerly initialize the underlying
1697 * logging system.
1698 *
1699 * @apiNote
1700 * This method is intended to be used after the system is fully initialized.
1701 * This method may trigger the immediate loading and initialization
1702 * of the {@link LoggerFinder} service, which may cause issues if the
1703 * Java Runtime is not ready to initialize the concrete service
1704 * implementation yet.
1705 * System classes which may be loaded early in the boot sequence and
1706 * need to log localized messages should create a logger using
1707 * {@link #getLogger(java.lang.String)} and then use the log methods that
1708 * take a resource bundle as parameter.
1709 *
1710 * @param name the name of the logger.
1711 * @param bundle a resource bundle.
1712 * @return an instance of {@link Logger} which will use the provided
1713 * resource bundle for message localization.
1714 * @throws NullPointerException if {@code name} is {@code null} or
1715 * {@code bundle} is {@code null}.
1716 * @throws IllegalCallerException if there is no Java caller frame on the
1717 * stack.
1718 *
1719 * @since 9
1720 */
1721 @CallerSensitive
1722 public static Logger getLogger(String name, ResourceBundle bundle) {
1723 final ResourceBundle rb = Objects.requireNonNull(bundle);
1724 Objects.requireNonNull(name);
1725 final Class<?> caller = Reflection.getCallerClass();
1726 if (caller == null) {
1727 throw new IllegalCallerException("no caller frame");
1728 }
1729 final SecurityManager sm = System.getSecurityManager();
1730 // We don't use LazyLoggers if a resource bundle is specified.
1731 // Bootstrap sensitive classes in the JDK do not use resource bundles
1732 // when logging. This could be revisited later, if it needs to.
1733 if (sm != null) {
1734 final PrivilegedAction<Logger> pa =
1735 () -> LoggerFinder.accessProvider()
1736 .getLocalizedLogger(name, rb, caller.getModule());
1737 return AccessController.doPrivileged(pa, null,
1738 LoggerFinder.LOGGERFINDER_PERMISSION);
1739 }
1740 return LoggerFinder.accessProvider()
1741 .getLocalizedLogger(name, rb, caller.getModule());
1742 }
1743
1744 /**
1745 * Terminates the currently running Java Virtual Machine. The
1746 * argument serves as a status code; by convention, a nonzero status
1747 * code indicates abnormal termination.
1748 * <p>
1749 * This method calls the {@code exit} method in class
1750 * {@code Runtime}. This method never returns normally.
1751 * <p>
1752 * The call {@code System.exit(n)} is effectively equivalent to
1753 * the call:
1754 * <blockquote><pre>
1755 * Runtime.getRuntime().exit(n)
1756 * </pre></blockquote>
1757 *
1758 * @param status exit status.
1759 * @throws SecurityException
1760 * if a security manager exists and its {@code checkExit}
1761 * method doesn't allow exit with the specified status.
1762 * @see java.lang.Runtime#exit(int)
1763 */
1764 public static void exit(int status) {
1765 Runtime.getRuntime().exit(status);
1766 }
1767
1768 /**
1769 * Runs the garbage collector in the Java Virtual Machine.
1770 * <p>
1771 * Calling the {@code gc} method suggests that the Java Virtual Machine
1772 * expend effort toward recycling unused objects in order to
1773 * make the memory they currently occupy available for reuse
1774 * by the Java Virtual Machine.
1775 * When control returns from the method call, the Java Virtual Machine
1776 * has made a best effort to reclaim space from all unused objects.
1777 * There is no guarantee that this effort will recycle any particular
1778 * number of unused objects, reclaim any particular amount of space, or
1779 * complete at any particular time, if at all, before the method returns or ever.
1780 * <p>
1781 * The call {@code System.gc()} is effectively equivalent to the
1782 * call:
1783 * <blockquote><pre>
1784 * Runtime.getRuntime().gc()
1785 * </pre></blockquote>
1786 *
1787 * @see java.lang.Runtime#gc()
1788 */
1789 public static void gc() {
1790 Runtime.getRuntime().gc();
1791 }
1792
1793 /**
1794 * Runs the finalization methods of any objects pending finalization.
1795 *
1796 * Calling this method suggests that the Java Virtual Machine expend
1797 * effort toward running the {@code finalize} methods of objects
1798 * that have been found to be discarded but whose {@code finalize}
1799 * methods have not yet been run. When control returns from the
1800 * method call, the Java Virtual Machine has made a best effort to
1801 * complete all outstanding finalizations.
1802 * <p>
1803 * The call {@code System.runFinalization()} is effectively
1804 * equivalent to the call:
1805 * <blockquote><pre>
1806 * Runtime.getRuntime().runFinalization()
1807 * </pre></blockquote>
1808 *
1809 * @see java.lang.Runtime#runFinalization()
1810 */
1811 public static void runFinalization() {
1812 Runtime.getRuntime().runFinalization();
1813 }
1814
1815 /**
1816 * Loads the native library specified by the filename argument. The filename
1817 * argument must be an absolute path name.
1818 *
1819 * If the filename argument, when stripped of any platform-specific library
1820 * prefix, path, and file extension, indicates a library whose name is,
1821 * for example, L, and a native library called L is statically linked
1822 * with the VM, then the JNI_OnLoad_L function exported by the library
1823 * is invoked rather than attempting to load a dynamic library.
1824 * A filename matching the argument does not have to exist in the
1825 * file system.
1826 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
1827 * for more details.
1828 *
1829 * Otherwise, the filename argument is mapped to a native library image in
1830 * an implementation-dependent manner.
1831 *
1832 * <p>
1833 * The call {@code System.load(name)} is effectively equivalent
1834 * to the call:
1835 * <blockquote><pre>
1836 * Runtime.getRuntime().load(name)
1837 * </pre></blockquote>
1838 *
1839 * @param filename the file to load.
1840 * @throws SecurityException if a security manager exists and its
1841 * {@code checkLink} method doesn't allow
1842 * loading of the specified dynamic library
1843 * @throws UnsatisfiedLinkError if either the filename is not an
1844 * absolute path name, the native library is not statically
1845 * linked with the VM, or the library cannot be mapped to
1846 * a native library image by the host system.
1847 * @throws NullPointerException if {@code filename} is {@code null}
1848 * @see java.lang.Runtime#load(java.lang.String)
1849 * @see java.lang.SecurityManager#checkLink(java.lang.String)
1850 */
1851 @CallerSensitive
1852 public static void load(String filename) {
1853 Runtime.getRuntime().load0(Reflection.getCallerClass(), filename);
1854 }
1855
1856 /**
1857 * Loads the native library specified by the {@code libname}
1858 * argument. The {@code libname} argument must not contain any platform
1859 * specific prefix, file extension or path. If a native library
1860 * called {@code libname} is statically linked with the VM, then the
1861 * JNI_OnLoad_{@code libname} function exported by the library is invoked.
1862 * See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
1863 * for more details.
1864 *
1865 * Otherwise, the libname argument is loaded from a system library
1866 * location and mapped to a native library image in an
1867 * implementation-dependent manner.
1868 * <p>
1869 * The call {@code System.loadLibrary(name)} is effectively
1870 * equivalent to the call
1871 * <blockquote><pre>
1872 * Runtime.getRuntime().loadLibrary(name)
1873 * </pre></blockquote>
1874 *
1875 * @param libname the name of the library.
1876 * @throws SecurityException if a security manager exists and its
1877 * {@code checkLink} method doesn't allow
1878 * loading of the specified dynamic library
1879 * @throws UnsatisfiedLinkError if either the libname argument
1880 * contains a file path, the native library is not statically
1881 * linked with the VM, or the library cannot be mapped to a
1882 * native library image by the host system.
1883 * @throws NullPointerException if {@code libname} is {@code null}
1884 * @see java.lang.Runtime#loadLibrary(java.lang.String)
1885 * @see java.lang.SecurityManager#checkLink(java.lang.String)
1886 */
1887 @CallerSensitive
1888 public static void loadLibrary(String libname) {
1889 Runtime.getRuntime().loadLibrary0(Reflection.getCallerClass(), libname);
1890 }
1891
1892 /**
1893 * Maps a library name into a platform-specific string representing
1894 * a native library.
1895 *
1896 * @param libname the name of the library.
1897 * @return a platform-dependent native library name.
1898 * @throws NullPointerException if {@code libname} is {@code null}
1899 * @see java.lang.System#loadLibrary(java.lang.String)
1900 * @see java.lang.ClassLoader#findLibrary(java.lang.String)
1901 * @since 1.2
1902 */
1903 public static native String mapLibraryName(String libname);
1904
1905 /**
1906 * Create PrintStream for stdout/err based on encoding.
1907 */
1908 private static PrintStream newPrintStream(FileOutputStream fos, String enc) {
1909 if (enc != null) {
1910 try {
1911 return new PrintStream(new BufferedOutputStream(fos, 128), true, enc);
1912 } catch (UnsupportedEncodingException uee) {}
1913 }
1914 return new PrintStream(new BufferedOutputStream(fos, 128), true);
1915 }
1916
1917 /**
1918 * Logs an exception/error at initialization time to stdout or stderr.
1919 *
1920 * @param printToStderr to print to stderr rather than stdout
1921 * @param printStackTrace to print the stack trace
1922 * @param msg the message to print before the exception, can be {@code null}
1923 * @param e the exception or error
1924 */
1925 private static void logInitException(boolean printToStderr,
1926 boolean printStackTrace,
1927 String msg,
1928 Throwable e) {
1929 if (VM.initLevel() < 1) {
1930 throw new InternalError("system classes not initialized");
1931 }
1932 PrintStream log = (printToStderr) ? err : out;
1933 if (msg != null) {
1934 log.println(msg);
1935 }
1936 if (printStackTrace) {
1937 e.printStackTrace(log);
1938 } else {
1939 log.println(e);
1940 for (Throwable suppressed : e.getSuppressed()) {
1941 log.println("Suppressed: " + suppressed);
1942 }
1943 Throwable cause = e.getCause();
1944 if (cause != null) {
1945 log.println("Caused by: " + cause);
1946 }
1947 }
1948 }
1949
1950 /**
1951 * Create the Properties object from a map - masking out system properties
1952 * that are not intended for public access.
1953 */
1954 private static Properties createProperties(Map<String, String> initialProps) {
1955 Properties properties = new Properties(initialProps.size());
1956 for (var entry : initialProps.entrySet()) {
1957 String prop = entry.getKey();
1958 switch (prop) {
1959 // Do not add private system properties to the Properties
1960 case "sun.nio.MaxDirectMemorySize":
1961 case "sun.nio.PageAlignDirectMemory":
1962 // used by java.lang.Integer.IntegerCache
1963 case "java.lang.Integer.IntegerCache.high":
1964 // used by sun.launcher.LauncherHelper
1965 case "sun.java.launcher.diag":
1966 // used by jdk.internal.loader.ClassLoaders
1967 case "jdk.boot.class.path.append":
1968 break;
1969 default:
1970 properties.put(prop, entry.getValue());
1971 }
1972 }
1973 return properties;
1974 }
1975
1976 /**
1977 * Initialize the system class. Called after thread initialization.
1978 */
1979 private static void initPhase1() {
1980 // VM might invoke JNU_NewStringPlatform() to set those encoding
1981 // sensitive properties (user.home, user.name, boot.class.path, etc.)
1982 // during "props" initialization.
1983 // The charset is initialized in System.c and does not depend on the Properties.
1984 Map<String, String> tempProps = SystemProps.initProperties();
1985 VersionProps.init(tempProps);
1986
1987 // There are certain system configurations that may be controlled by
1988 // VM options such as the maximum amount of direct memory and
1989 // Integer cache size used to support the object identity semantics
1990 // of autoboxing. Typically, the library will obtain these values
1991 // from the properties set by the VM. If the properties are for
1992 // internal implementation use only, these properties should be
1993 // masked from the system properties.
1994 //
1995 // Save a private copy of the system properties object that
1996 // can only be accessed by the internal implementation.
1997 VM.saveProperties(tempProps);
1998 props = createProperties(tempProps);
1999
2000 StaticProperty.javaHome(); // Load StaticProperty to cache the property values
2001
2002 lineSeparator = props.getProperty("line.separator");
2003
2004 FileInputStream fdIn = new FileInputStream(FileDescriptor.in);
2005 FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out);
2006 FileOutputStream fdErr = new FileOutputStream(FileDescriptor.err);
2007 setIn0(new BufferedInputStream(fdIn));
2008 setOut0(newPrintStream(fdOut, props.getProperty("sun.stdout.encoding")));
2009 setErr0(newPrintStream(fdErr, props.getProperty("sun.stderr.encoding")));
2010
2011 // Setup Java signal handlers for HUP, TERM, and INT (where available).
2012 Terminator.setup();
2013
2014 // Initialize any miscellaneous operating system settings that need to be
2015 // set for the class libraries. Currently this is no-op everywhere except
2016 // for Windows where the process-wide error mode is set before the java.io
2017 // classes are used.
2018 VM.initializeOSEnvironment();
2019
2020 // The main thread is not added to its thread group in the same
2021 // way as other threads; we must do it ourselves here.
2022 Thread current = Thread.currentThread();
2023 current.getThreadGroup().add(current);
2024
2025 // register shared secrets
2026 setJavaLangAccess();
2027
2028 // Subsystems that are invoked during initialization can invoke
2029 // VM.isBooted() in order to avoid doing things that should
2030 // wait until the VM is fully initialized. The initialization level
2031 // is incremented from 0 to 1 here to indicate the first phase of
2032 // initialization has completed.
2033 // IMPORTANT: Ensure that this remains the last initialization action!
2034 VM.initLevel(1);
2035 }
2036
2037 // @see #initPhase2()
2038 static ModuleLayer bootLayer;
2039
2040 /*
2041 * Invoked by VM. Phase 2 module system initialization.
2042 * Only classes in java.base can be loaded in this phase.
2043 *
2044 * @param printToStderr print exceptions to stderr rather than stdout
2045 * @param printStackTrace print stack trace when exception occurs
2046 *
2047 * @return JNI_OK for success, JNI_ERR for failure
2048 */
2049 private static int initPhase2(boolean printToStderr, boolean printStackTrace) {
2050 try {
2051 bootLayer = ModuleBootstrap.boot();
2052 } catch (Exception | Error e) {
2053 logInitException(printToStderr, printStackTrace,
2054 "Error occurred during initialization of boot layer", e);
2055 return -1; // JNI_ERR
2056 }
2057
2058 // module system initialized
2059 VM.initLevel(2);
2060
2061 return 0; // JNI_OK
2062 }
2063
2064 /*
2065 * Invoked by VM. Phase 3 is the final system initialization:
2066 * 1. set security manager
2067 * 2. set system class loader
2068 * 3. set TCCL
2069 *
2070 * This method must be called after the module system initialization.
2071 * The security manager and system class loader may be a custom class from
2072 * the application classpath or modulepath.
2073 */
2074 private static void initPhase3() {
2075 String smProp = System.getProperty("java.security.manager");
2076 if (smProp != null) {
2077 switch (smProp) {
2078 case "disallow":
2079 allowSecurityManager = NEVER;
2080 break;
2081 case "allow":
2082 allowSecurityManager = MAYBE;
2083 break;
2084 case "":
2085 case "default":
2086 setSecurityManager(new SecurityManager());
2087 allowSecurityManager = MAYBE;
2088 break;
2089 default:
2090 try {
2091 ClassLoader cl = ClassLoader.getBuiltinAppClassLoader();
2092 Class<?> c = Class.forName(smProp, false, cl);
2093 Constructor<?> ctor = c.getConstructor();
2094 // Must be a public subclass of SecurityManager with
2095 // a public no-arg constructor
2096 if (!SecurityManager.class.isAssignableFrom(c) ||
2097 !Modifier.isPublic(c.getModifiers()) ||
2098 !Modifier.isPublic(ctor.getModifiers())) {
2099 throw new Error("Could not create SecurityManager: "
2100 + ctor.toString());
2101 }
2102 // custom security manager may be in non-exported package
2103 ctor.setAccessible(true);
2104 SecurityManager sm = (SecurityManager) ctor.newInstance();
2105 setSecurityManager(sm);
2106 } catch (Exception e) {
2107 throw new InternalError("Could not create SecurityManager", e);
2108 }
2109 allowSecurityManager = MAYBE;
2110 }
2111 } else {
2112 allowSecurityManager = MAYBE;
2113 }
2114
2115 // initializing the system class loader
2116 VM.initLevel(3);
2117
2118 // system class loader initialized
2119 ClassLoader scl = ClassLoader.initSystemClassLoader();
2120
2121 // set TCCL
2122 Thread.currentThread().setContextClassLoader(scl);
2123
2124 // system is fully initialized
2125 VM.initLevel(4);
2126 }
2127
2128 private static void setJavaLangAccess() {
2129 // Allow privileged classes outside of java.lang
2130 SharedSecrets.setJavaLangAccess(new JavaLangAccess() {
2131 public List<Method> getDeclaredPublicMethods(Class<?> klass, String name, Class<?>... parameterTypes) {
2132 return klass.getDeclaredPublicMethods(name, parameterTypes);
2133 }
2134 public jdk.internal.reflect.ConstantPool getConstantPool(Class<?> klass) {
2135 return klass.getConstantPool();
2136 }
2137 public boolean casAnnotationType(Class<?> klass, AnnotationType oldType, AnnotationType newType) {
2138 return klass.casAnnotationType(oldType, newType);
2139 }
2140 public AnnotationType getAnnotationType(Class<?> klass) {
2141 return klass.getAnnotationType();
2142 }
2143 public Map<Class<? extends Annotation>, Annotation> getDeclaredAnnotationMap(Class<?> klass) {
2144 return klass.getDeclaredAnnotationMap();
2145 }
2146 public byte[] getRawClassAnnotations(Class<?> klass) {
2147 return klass.getRawAnnotations();
2148 }
2149 public byte[] getRawClassTypeAnnotations(Class<?> klass) {
2150 return klass.getRawTypeAnnotations();
2151 }
2152 public byte[] getRawExecutableTypeAnnotations(Executable executable) {
2153 return Class.getExecutableTypeAnnotationBytes(executable);
2154 }
2155 public <E extends Enum<E>>
2156 E[] getEnumConstantsShared(Class<E> klass) {
2157 return klass.getEnumConstantsShared();
2158 }
2159 public void blockedOn(Interruptible b) {
2160 Thread.blockedOn(b);
2161 }
2162 public void registerShutdownHook(int slot, boolean registerShutdownInProgress, Runnable hook) {
2163 Shutdown.add(slot, registerShutdownInProgress, hook);
2164 }
2165 public Thread newThreadWithAcc(Runnable target, AccessControlContext acc) {
2166 return new Thread(target, acc);
2167 }
2168 @SuppressWarnings("deprecation")
2169 public void invokeFinalize(Object o) throws Throwable {
2170 o.finalize();
2171 }
2172 public ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap(ClassLoader cl) {
2173 return cl.createOrGetClassLoaderValueMap();
2174 }
2175 public Class<?> defineClass(ClassLoader loader, String name, byte[] b, ProtectionDomain pd, String source) {
2176 return ClassLoader.defineClass1(loader, name, b, 0, b.length, pd, source);
2177 }
2178 public Class<?> findBootstrapClassOrNull(ClassLoader cl, String name) {
2179 return cl.findBootstrapClassOrNull(name);
2180 }
2181 public Package definePackage(ClassLoader cl, String name, Module module) {
2182 return cl.definePackage(name, module);
2183 }
2184 public String fastUUID(long lsb, long msb) {
2185 return Long.fastUUID(lsb, msb);
2186 }
2187 public void addNonExportedPackages(ModuleLayer layer) {
2188 SecurityManager.addNonExportedPackages(layer);
2189 }
2190 public void invalidatePackageAccessCache() {
2191 SecurityManager.invalidatePackageAccessCache();
2192 }
2193 public Module defineModule(ClassLoader loader,
2194 ModuleDescriptor descriptor,
2195 URI uri) {
2196 return new Module(null, loader, descriptor, uri);
2197 }
2198 public Module defineUnnamedModule(ClassLoader loader) {
2199 return new Module(loader);
2200 }
2201 public void addReads(Module m1, Module m2) {
2202 m1.implAddReads(m2);
2203 }
2204 public void addReadsAllUnnamed(Module m) {
2205 m.implAddReadsAllUnnamed();
2206 }
2207 public void addExports(Module m, String pn, Module other) {
2208 m.implAddExports(pn, other);
2209 }
2210 public void addExportsToAllUnnamed(Module m, String pn) {
2211 m.implAddExportsToAllUnnamed(pn);
2212 }
2213 public void addOpens(Module m, String pn, Module other) {
2214 m.implAddOpens(pn, other);
2215 }
2216 public void addOpensToAllUnnamed(Module m, String pn) {
2217 m.implAddOpensToAllUnnamed(pn);
2218 }
2219 public void addOpensToAllUnnamed(Module m, Set<String> concealedPackages, Set<String> exportedPackages) {
2220 m.implAddOpensToAllUnnamed(concealedPackages, exportedPackages);
2221 }
2222 public void addUses(Module m, Class<?> service) {
2223 m.implAddUses(service);
2224 }
2225 public boolean isReflectivelyExported(Module m, String pn, Module other) {
2226 return m.isReflectivelyExported(pn, other);
2227 }
2228 public boolean isReflectivelyOpened(Module m, String pn, Module other) {
2229 return m.isReflectivelyOpened(pn, other);
2230 }
2231 public ServicesCatalog getServicesCatalog(ModuleLayer layer) {
2232 return layer.getServicesCatalog();
2233 }
2234 public Stream<ModuleLayer> layers(ModuleLayer layer) {
2235 return layer.layers();
2236 }
2237 public Stream<ModuleLayer> layers(ClassLoader loader) {
2238 return ModuleLayer.layers(loader);
2239 }
2240
2241 public String newStringNoRepl(byte[] bytes, Charset cs) throws CharacterCodingException {
2242 return StringCoding.newStringNoRepl(bytes, cs);
2243 }
2244
2245 public byte[] getBytesNoRepl(String s, Charset cs) throws CharacterCodingException {
2246 return StringCoding.getBytesNoRepl(s, cs);
2247 }
2248
2249 public String newStringUTF8NoRepl(byte[] bytes, int off, int len) {
2250 return StringCoding.newStringUTF8NoRepl(bytes, off, len);
2251 }
2252
2253 public byte[] getBytesUTF8NoRepl(String s) {
2254 return StringCoding.getBytesUTF8NoRepl(s);
2255 }
2256
2257 public void setCause(Throwable t, Throwable cause) {
2258 t.setCause(cause);
2259 }
2260 });
2261 }
2262 }