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