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