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/*
* Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.lang;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.Console;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.io.UnsupportedEncodingException;
import java.lang.annotation.Annotation;
import java.lang.module.ModuleDescriptor;
import java.lang.reflect.Constructor;
import java.lang.reflect.Executable;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.net.URI;
import java.nio.charset.CharacterCodingException;
import java.security.AccessControlContext;
import java.security.ProtectionDomain;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.nio.channels.Channel;
import java.nio.channels.spi.SelectorProvider;
import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Properties;
import java.util.PropertyPermission;
import java.util.ResourceBundle;
import java.util.function.Supplier;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Stream;
import jdk.internal.util.StaticProperty;
import jdk.internal.module.ModuleBootstrap;
import jdk.internal.module.ServicesCatalog;
import jdk.internal.reflect.CallerSensitive;
import jdk.internal.reflect.Reflection;
import jdk.internal.HotSpotIntrinsicCandidate;
import jdk.internal.misc.JavaLangAccess;
import jdk.internal.misc.SharedSecrets;
import jdk.internal.misc.VM;
import jdk.internal.logger.LoggerFinderLoader;
import jdk.internal.logger.LazyLoggers;
import jdk.internal.logger.LocalizedLoggerWrapper;
import sun.nio.fs.DefaultFileSystemProvider;
import sun.reflect.annotation.AnnotationType;
import sun.nio.ch.Interruptible;
import sun.security.util.SecurityConstants;
/**
* The {@code System} class contains several useful class fields
* and methods. It cannot be instantiated.
*
* Among the facilities provided by the {@code System} class
* are standard input, standard output, and error output streams;
* access to externally defined properties and environment
* variables; a means of loading files and libraries; and a utility
* method for quickly copying a portion of an array.
*
* @since 1.0
*/
public final class System {
/* Register the natives via the static initializer.
*
* VM will invoke the initializeSystemClass method to complete
* the initialization for this class separated from clinit.
* Note that to use properties set by the VM, see the constraints
* described in the initializeSystemClass method.
*/
private static native void registerNatives();
static {
registerNatives();
}
/** Don't let anyone instantiate this class */
private System() {
}
/**
* The "standard" input stream. This stream is already
* open and ready to supply input data. Typically this stream
* corresponds to keyboard input or another input source specified by
* the host environment or user.
*/
public static final InputStream in = null;
/**
* The "standard" output stream. This stream is already
* open and ready to accept output data. Typically this stream
* corresponds to display output or another output destination
* specified by the host environment or user.
* <p>
* For simple stand-alone Java applications, a typical way to write
* a line of output data is:
* <blockquote><pre>
* System.out.println(data)
* </pre></blockquote>
* <p>
* See the {@code println} methods in class {@code PrintStream}.
*
* @see java.io.PrintStream#println()
* @see java.io.PrintStream#println(boolean)
* @see java.io.PrintStream#println(char)
* @see java.io.PrintStream#println(char[])
* @see java.io.PrintStream#println(double)
* @see java.io.PrintStream#println(float)
* @see java.io.PrintStream#println(int)
* @see java.io.PrintStream#println(long)
* @see java.io.PrintStream#println(java.lang.Object)
* @see java.io.PrintStream#println(java.lang.String)
*/
public static final PrintStream out = null;
/**
* The "standard" error output stream. This stream is already
* open and ready to accept output data.
* <p>
* Typically this stream corresponds to display output or another
* output destination specified by the host environment or user. By
* convention, this output stream is used to display error messages
* or other information that should come to the immediate attention
* of a user even if the principal output stream, the value of the
* variable {@code out}, has been redirected to a file or other
* destination that is typically not continuously monitored.
*/
public static final PrintStream err = null;
/* The security manager for the system.
*/
private static volatile SecurityManager security;
/**
* Reassigns the "standard" input stream.
*
* First, if there is a security manager, its {@code checkPermission}
* method is called with a {@code RuntimePermission("setIO")} permission
* to see if it's ok to reassign the "standard" input stream.
*
* @param in the new standard input stream.
*
* @throws SecurityException
* if a security manager exists and its
* {@code checkPermission} method doesn't allow
* reassigning of the standard input stream.
*
* @see SecurityManager#checkPermission
* @see java.lang.RuntimePermission
*
* @since 1.1
*/
public static void setIn(InputStream in) {
checkIO();
setIn0(in);
}
/**
* Reassigns the "standard" output stream.
*
* First, if there is a security manager, its {@code checkPermission}
* method is called with a {@code RuntimePermission("setIO")} permission
* to see if it's ok to reassign the "standard" output stream.
*
* @param out the new standard output stream
*
* @throws SecurityException
* if a security manager exists and its
* {@code checkPermission} method doesn't allow
* reassigning of the standard output stream.
*
* @see SecurityManager#checkPermission
* @see java.lang.RuntimePermission
*
* @since 1.1
*/
public static void setOut(PrintStream out) {
checkIO();
setOut0(out);
}
/**
* Reassigns the "standard" error output stream.
*
* First, if there is a security manager, its {@code checkPermission}
* method is called with a {@code RuntimePermission("setIO")} permission
* to see if it's ok to reassign the "standard" error output stream.
*
* @param err the new standard error output stream.
*
* @throws SecurityException
* if a security manager exists and its
* {@code checkPermission} method doesn't allow
* reassigning of the standard error output stream.
*
* @see SecurityManager#checkPermission
* @see java.lang.RuntimePermission
*
* @since 1.1
*/
public static void setErr(PrintStream err) {
checkIO();
setErr0(err);
}
private static volatile Console cons;
/**
* Returns the unique {@link java.io.Console Console} object associated
* with the current Java virtual machine, if any.
*
* @return The system console, if any, otherwise {@code null}.
*
* @since 1.6
*/
public static Console console() {
Console c;
if ((c = cons) == null) {
synchronized (System.class) {
if ((c = cons) == null) {
cons = c = SharedSecrets.getJavaIOAccess().console();
}
}
}
return c;
}
/**
* Returns the channel inherited from the entity that created this
* Java virtual machine.
*
* This method returns the channel obtained by invoking the
* {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
* inheritedChannel} method of the system-wide default
* {@link java.nio.channels.spi.SelectorProvider} object.
*
* <p> In addition to the network-oriented channels described in
* {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
* inheritedChannel}, this method may return other kinds of
* channels in the future.
*
* @return The inherited channel, if any, otherwise {@code null}.
*
* @throws IOException
* If an I/O error occurs
*
* @throws SecurityException
* If a security manager is present and it does not
* permit access to the channel.
*
* @since 1.5
*/
public static Channel inheritedChannel() throws IOException {
return SelectorProvider.provider().inheritedChannel();
}
private static void checkIO() {
SecurityManager sm = getSecurityManager();
if (sm != null) {
sm.checkPermission(new RuntimePermission("setIO"));
}
}
private static native void setIn0(InputStream in);
private static native void setOut0(PrintStream out);
private static native void setErr0(PrintStream err);
/**
* Sets the System security.
*
* If there is a security manager already installed, this method first
* calls the security manager's {@code checkPermission} method
* with a {@code RuntimePermission("setSecurityManager")}
* permission to ensure it's ok to replace the existing
* security manager.
* This may result in throwing a {@code SecurityException}.
*
* <p> Otherwise, the argument is established as the current
* security manager. If the argument is {@code null} and no
* security manager has been established, then no action is taken and
* the method simply returns.
*
* @param s the security manager.
* @throws SecurityException if the security manager has already
* been set and its {@code checkPermission} method
* doesn't allow it to be replaced.
* @see #getSecurityManager
* @see SecurityManager#checkPermission
* @see java.lang.RuntimePermission
*/
public static void setSecurityManager(final SecurityManager s) {
if (security == null) {
// ensure image reader is initialized
Object.class.getResource("java/lang/ANY");
// ensure the default file system is initialized
DefaultFileSystemProvider.theFileSystem();
}
if (s != null) {
try {
s.checkPackageAccess("java.lang");
} catch (Exception e) {
// no-op
}
}
setSecurityManager0(s);
}
private static synchronized
void setSecurityManager0(final SecurityManager s) {
SecurityManager sm = getSecurityManager();
if (sm != null) {
// ask the currently installed security manager if we
// can replace it.
sm.checkPermission(new RuntimePermission
("setSecurityManager"));
}
if ((s != null) && (s.getClass().getClassLoader() != null)) {
// New security manager class is not on bootstrap classpath.
// Cause policy to get initialized before we install the new
// security manager, in order to prevent infinite loops when
// trying to initialize the policy (which usually involves
// accessing some security and/or system properties, which in turn
// calls the installed security manager's checkPermission method
// which will loop infinitely if there is a non-system class
// (in this case: the new security manager class) on the stack).
AccessController.doPrivileged(new PrivilegedAction<>() {
public Object run() {
s.getClass().getProtectionDomain().implies
(SecurityConstants.ALL_PERMISSION);
return null;
}
});
}
security = s;
}
/**
* Gets the system security interface.
*
* @return if a security manager has already been established for the
* current application, then that security manager is returned;
* otherwise, {@code null} is returned.
* @see #setSecurityManager
*/
public static SecurityManager getSecurityManager() {
return security;
}
/**
* Returns the current time in milliseconds. Note that
* while the unit of time of the return value is a millisecond,
* the granularity of the value depends on the underlying
* operating system and may be larger. For example, many
* operating systems measure time in units of tens of
* milliseconds.
*
* <p> See the description of the class {@code Date} for
* a discussion of slight discrepancies that may arise between
* "computer time" and coordinated universal time (UTC).
*
* @return the difference, measured in milliseconds, between
* the current time and midnight, January 1, 1970 UTC.
* @see java.util.Date
*/
@HotSpotIntrinsicCandidate
public static native long currentTimeMillis();
/**
* Returns the current value of the running Java Virtual Machine's
* high-resolution time source, in nanoseconds.
*
* This method can only be used to measure elapsed time and is
* not related to any other notion of system or wall-clock time.
* The value returned represents nanoseconds since some fixed but
* arbitrary <i>origin</i> time (perhaps in the future, so values
* may be negative). The same origin is used by all invocations of
* this method in an instance of a Java virtual machine; other
* virtual machine instances are likely to use a different origin.
*
* <p>This method provides nanosecond precision, but not necessarily
* nanosecond resolution (that is, how frequently the value changes)
* - no guarantees are made except that the resolution is at least as
* good as that of {@link #currentTimeMillis()}.
*
* <p>Differences in successive calls that span greater than
* approximately 292 years (2<sup>63</sup> nanoseconds) will not
* correctly compute elapsed time due to numerical overflow.
*
* <p>The values returned by this method become meaningful only when
* the difference between two such values, obtained within the same
* instance of a Java virtual machine, is computed.
*
* <p>For example, to measure how long some code takes to execute:
* <pre> {@code
* long startTime = System.nanoTime();
* // ... the code being measured ...
* long elapsedNanos = System.nanoTime() - startTime;}</pre>
*
* <p>To compare elapsed time against a timeout, use <pre> {@code
* if (System.nanoTime() - startTime >= timeoutNanos) ...}</pre>
* instead of <pre> {@code
* if (System.nanoTime() >= startTime + timeoutNanos) ...}</pre>
* because of the possibility of numerical overflow.
*
* @return the current value of the running Java Virtual Machine's
* high-resolution time source, in nanoseconds
* @since 1.5
*/
@HotSpotIntrinsicCandidate
public static native long nanoTime();
/**
* Copies an array from the specified source array, beginning at the
* specified position, to the specified position of the destination array.
* A subsequence of array components are copied from the source
* array referenced by {@code src} to the destination array
* referenced by {@code dest}. The number of components copied is
* equal to the {@code length} argument. The components at
* positions {@code srcPos} through
* {@code srcPos+length-1} in the source array are copied into
* positions {@code destPos} through
* {@code destPos+length-1}, respectively, of the destination
* array.
* <p>
* If the {@code src} and {@code dest} arguments refer to the
* same array object, then the copying is performed as if the
* components at positions {@code srcPos} through
* {@code srcPos+length-1} were first copied to a temporary
* array with {@code length} components and then the contents of
* the temporary array were copied into positions
* {@code destPos} through {@code destPos+length-1} of the
* destination array.
* <p>
* If {@code dest} is {@code null}, then a
* {@code NullPointerException} is thrown.
* <p>
* If {@code src} is {@code null}, then a
* {@code NullPointerException} is thrown and the destination
* array is not modified.
* <p>
* Otherwise, if any of the following is true, an
* {@code ArrayStoreException} is thrown and the destination is
* not modified:
* <ul>
* <li>The {@code src} argument refers to an object that is not an
* array.
* <li>The {@code dest} argument refers to an object that is not an
* array.
* <li>The {@code src} argument and {@code dest} argument refer
* to arrays whose component types are different primitive types.
* <li>The {@code src} argument refers to an array with a primitive
* component type and the {@code dest} argument refers to an array
* with a reference component type.
* <li>The {@code src} argument refers to an array with a reference
* component type and the {@code dest} argument refers to an array
* with a primitive component type.
* </ul>
* <p>
* Otherwise, if any of the following is true, an
* {@code IndexOutOfBoundsException} is
* thrown and the destination is not modified:
* <ul>
* <li>The {@code srcPos} argument is negative.
* <li>The {@code destPos} argument is negative.
* <li>The {@code length} argument is negative.
* <li>{@code srcPos+length} is greater than
* {@code src.length}, the length of the source array.
* <li>{@code destPos+length} is greater than
* {@code dest.length}, the length of the destination array.
* </ul>
* <p>
* Otherwise, if any actual component of the source array from
* position {@code srcPos} through
* {@code srcPos+length-1} cannot be converted to the component
* type of the destination array by assignment conversion, an
* {@code ArrayStoreException} is thrown. In this case, let
* <b><i>k</i></b> be the smallest nonnegative integer less than
* length such that {@code src[srcPos+}<i>k</i>{@code ]}
* cannot be converted to the component type of the destination
* array; when the exception is thrown, source array components from
* positions {@code srcPos} through
* {@code srcPos+}<i>k</i>{@code -1}
* will already have been copied to destination array positions
* {@code destPos} through
* {@code destPos+}<i>k</I>{@code -1} and no other
* positions of the destination array will have been modified.
* (Because of the restrictions already itemized, this
* paragraph effectively applies only to the situation where both
* arrays have component types that are reference types.)
*
* @param src the source array.
* @param srcPos starting position in the source array.
* @param dest the destination array.
* @param destPos starting position in the destination data.
* @param length the number of array elements to be copied.
* @throws IndexOutOfBoundsException if copying would cause
* access of data outside array bounds.
* @throws ArrayStoreException if an element in the {@code src}
* array could not be stored into the {@code dest} array
* because of a type mismatch.
* @throws NullPointerException if either {@code src} or
* {@code dest} is {@code null}.
*/
@HotSpotIntrinsicCandidate
public static native void arraycopy(Object src, int srcPos,
Object dest, int destPos,
int length);
/**
* Returns the same hash code for the given object as
* would be returned by the default method hashCode(),
* whether or not the given object's class overrides
* hashCode().
* The hash code for the null reference is zero.
*
* @param x object for which the hashCode is to be calculated
* @return the hashCode
* @since 1.1
* @see Object#hashCode
* @see java.util.Objects#hashCode(Object)
*/
@HotSpotIntrinsicCandidate
public static native int identityHashCode(Object x);
/**
* System properties. The following properties are guaranteed to be defined:
* <dl>
* <dt>java.version <dd>Java version number
* <dt>java.version.date <dd>Java version date
* <dt>java.vendor <dd>Java vendor specific string
* <dt>java.vendor.url <dd>Java vendor URL
* <dt>java.vendor.version <dd>Java vendor version
* <dt>java.home <dd>Java installation directory
* <dt>java.class.version <dd>Java class version number
* <dt>java.class.path <dd>Java classpath
* <dt>os.name <dd>Operating System Name
* <dt>os.arch <dd>Operating System Architecture
* <dt>os.version <dd>Operating System Version
* <dt>file.separator <dd>File separator ("/" on Unix)
* <dt>path.separator <dd>Path separator (":" on Unix)
* <dt>line.separator <dd>Line separator ("\n" on Unix)
* <dt>user.name <dd>User account name
* <dt>user.home <dd>User home directory
* <dt>user.dir <dd>User's current working directory
* </dl>
*/
private static Properties props;
private static native Properties initProperties(Properties props);
/**
* Determines the current system properties.
*
* First, if there is a security manager, its
* {@code checkPropertiesAccess} method is called with no
* arguments. This may result in a security exception.
* <p>
* The current set of system properties for use by the
* {@link #getProperty(String)} method is returned as a
* {@code Properties} object. If there is no current set of
* system properties, a set of system properties is first created and
* initialized. This set of system properties always includes values
* for the following keys:
* <table class="striped" style="text-align:left">
* <caption style="display:none">Shows property keys and associated values</caption>
* <thead>
* <tr><th scope="col">Key</th>
* <th scope="col">Description of Associated Value</th></tr>
* </thead>
* <tbody>
* <tr><th scope="row">{@code java.version}</th>
* <td>Java Runtime Environment version, which may be interpreted
* as a {@link Runtime.Version}</td></tr>
* <tr><th scope="row">{@code java.version.date}</th>
* <td>Java Runtime Environment version date, in ISO-8601 YYYY-MM-DD
* format, which may be interpreted as a {@link
* java.time.LocalDate}</td></tr>
* <tr><th scope="row">{@code java.vendor}</th>
* <td>Java Runtime Environment vendor</td></tr>
* <tr><th scope="row">{@code java.vendor.url}</th>
* <td>Java vendor URL</td></tr>
* <tr><th scope="row">{@code java.vendor.version}</th>
* <td>Java vendor version</td></tr>
* <tr><th scope="row">{@code java.home}</th>
* <td>Java installation directory</td></tr>
* <tr><th scope="row">{@code java.vm.specification.version}</th>
* <td>Java Virtual Machine specification version, whose value is the
* {@linkplain Runtime.Version#feature feature} element of the
* {@linkplain Runtime#version() runtime version}</td></tr>
* <tr><th scope="row">{@code java.vm.specification.vendor}</th>
* <td>Java Virtual Machine specification vendor</td></tr>
* <tr><th scope="row">{@code java.vm.specification.name}</th>
* <td>Java Virtual Machine specification name</td></tr>
* <tr><th scope="row">{@code java.vm.version}</th>
* <td>Java Virtual Machine implementation version which may be
* interpreted as a {@link Runtime.Version}</td></tr>
* <tr><th scope="row">{@code java.vm.vendor}</th>
* <td>Java Virtual Machine implementation vendor</td></tr>
* <tr><th scope="row">{@code java.vm.name}</th>
* <td>Java Virtual Machine implementation name</td></tr>
* <tr><th scope="row">{@code java.specification.version}</th>
* <td>Java Runtime Environment specification version, whose value is
* the {@linkplain Runtime.Version#feature feature} element of the
* {@linkplain Runtime#version() runtime version}</td></tr>
* <tr><th scope="row">{@code java.specification.vendor}</th>
* <td>Java Runtime Environment specification vendor</td></tr>
* <tr><th scope="row">{@code java.specification.name}</th>
* <td>Java Runtime Environment specification name</td></tr>
* <tr><th scope="row">{@code java.class.version}</th>
* <td>Java class format version number</td></tr>
* <tr><th scope="row">{@code java.class.path}</th>
* <td>Java class path (refer to
* {@link ClassLoader#getSystemClassLoader()} for details)</td></tr>
* <tr><th scope="row">{@code java.library.path}</th>
* <td>List of paths to search when loading libraries</td></tr>
* <tr><th scope="row">{@code java.io.tmpdir}</th>
* <td>Default temp file path</td></tr>
* <tr><th scope="row">{@code java.compiler}</th>
* <td>Name of JIT compiler to use</td></tr>
* <tr><th scope="row">{@code os.name}</th>
* <td>Operating system name</td></tr>
* <tr><th scope="row">{@code os.arch}</th>
* <td>Operating system architecture</td></tr>
* <tr><th scope="row">{@code os.version}</th>
* <td>Operating system version</td></tr>
* <tr><th scope="row">{@code file.separator}</th>
* <td>File separator ("/" on UNIX)</td></tr>
* <tr><th scope="row">{@code path.separator}</th>
* <td>Path separator (":" on UNIX)</td></tr>
* <tr><th scope="row">{@code line.separator}</th>
* <td>Line separator ("\n" on UNIX)</td></tr>
* <tr><th scope="row">{@code user.name}</th>
* <td>User's account name</td></tr>
* <tr><th scope="row">{@code user.home}</th>
* <td>User's home directory</td></tr>
* <tr><th scope="row">{@code user.dir}</th>
* <td>User's current working directory</td></tr>
* </tbody>
* </table>
* <p>
* Multiple paths in a system property value are separated by the path
* separator character of the platform.
* <p>
* Note that even if the security manager does not permit the
* {@code getProperties} operation, it may choose to permit the
* {@link #getProperty(String)} operation.
*
* @apiNote
* <strong>Changing a standard system property may have unpredictable results
* unless otherwise specified.</strong>
* Property values may be cached during initialization or on first use.
* Setting a standard property after initialization using {@link #getProperties()},
* {@link #setProperties(Properties)}, {@link #setProperty(String, String)}, or
* {@link #clearProperty(String)} may not have the desired effect.
*
* @implNote
* In addition to the standard system properties, the system
* properties may include the following keys:
* <table class="striped">
* <caption style="display:none">Shows property keys and associated values</caption>
* <thead>
* <tr><th scope="col">Key</th>
* <th scope="col">Description of Associated Value</th></tr>
* </thead>
* <tbody>
* <tr><th scope="row">{@code jdk.module.path}</th>
* <td>The application module path</td></tr>
* <tr><th scope="row">{@code jdk.module.upgrade.path}</th>
* <td>The upgrade module path</td></tr>
* <tr><th scope="row">{@code jdk.module.main}</th>
* <td>The module name of the initial/main module</td></tr>
* <tr><th scope="row">{@code jdk.module.main.class}</th>
* <td>The main class name of the initial module</td></tr>
* </tbody>
* </table>
*
* @return the system properties
* @throws SecurityException if a security manager exists and its
* {@code checkPropertiesAccess} method doesn't allow access
* to the system properties.
* @see #setProperties
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkPropertiesAccess()
* @see java.util.Properties
*/
public static Properties getProperties() {
SecurityManager sm = getSecurityManager();
if (sm != null) {
sm.checkPropertiesAccess();
}
return props;
}
/**
* Returns the system-dependent line separator string. It always
* returns the same value - the initial value of the {@linkplain
* #getProperty(String) system property} {@code line.separator}.
*
* <p>On UNIX systems, it returns {@code "\n"}; on Microsoft
* Windows systems it returns {@code "\r\n"}.
*
* @return the system-dependent line separator string
* @since 1.7
*/
public static String lineSeparator() {
return lineSeparator;
}
private static String lineSeparator;
/**
* Sets the system properties to the {@code Properties} argument.
*
* First, if there is a security manager, its
* {@code checkPropertiesAccess} method is called with no
* arguments. This may result in a security exception.
* <p>
* The argument becomes the current set of system properties for use
* by the {@link #getProperty(String)} method. If the argument is
* {@code null}, then the current set of system properties is
* forgotten.
*
* @apiNote
* <strong>Changing a standard system property may have unpredictable results
* unless otherwise specified</strong>.
* See {@linkplain #getProperties getProperties} for details.
*
* @param props the new system properties.
* @throws SecurityException if a security manager exists and its
* {@code checkPropertiesAccess} method doesn't allow access
* to the system properties.
* @see #getProperties
* @see java.util.Properties
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkPropertiesAccess()
*/
public static void setProperties(Properties props) {
SecurityManager sm = getSecurityManager();
if (sm != null) {
sm.checkPropertiesAccess();
}
if (props == null) {
props = new Properties();
initProperties(props);
System.props = props;
VersionProps.init();
} else {
System.props = props;
}
}
/**
* Gets the system property indicated by the specified key.
*
* First, if there is a security manager, its
* {@code checkPropertyAccess} method is called with the key as
* its argument. This may result in a SecurityException.
* <p>
* If there is no current set of system properties, a set of system
* properties is first created and initialized in the same manner as
* for the {@code getProperties} method.
*
* @apiNote
* <strong>Changing a standard system property may have unpredictable results
* unless otherwise specified</strong>.
* See {@linkplain #getProperties getProperties} for details.
*
* @param key the name of the system property.
* @return the string value of the system property,
* or {@code null} if there is no property with that key.
*
* @throws SecurityException if a security manager exists and its
* {@code checkPropertyAccess} method doesn't allow
* access to the specified system property.
* @throws NullPointerException if {@code key} is {@code null}.
* @throws IllegalArgumentException if {@code key} is empty.
* @see #setProperty
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
* @see java.lang.System#getProperties()
*/
public static String getProperty(String key) {
checkKey(key);
SecurityManager sm = getSecurityManager();
if (sm != null) {
sm.checkPropertyAccess(key);
}
return props.getProperty(key);
}
/**
* Gets the system property indicated by the specified key.
*
* First, if there is a security manager, its
* {@code checkPropertyAccess} method is called with the
* {@code key} as its argument.
* <p>
* If there is no current set of system properties, a set of system
* properties is first created and initialized in the same manner as
* for the {@code getProperties} method.
*
* @param key the name of the system property.
* @param def a default value.
* @return the string value of the system property,
* or the default value if there is no property with that key.
*
* @throws SecurityException if a security manager exists and its
* {@code checkPropertyAccess} method doesn't allow
* access to the specified system property.
* @throws NullPointerException if {@code key} is {@code null}.
* @throws IllegalArgumentException if {@code key} is empty.
* @see #setProperty
* @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
* @see java.lang.System#getProperties()
*/
public static String getProperty(String key, String def) {
checkKey(key);
SecurityManager sm = getSecurityManager();
if (sm != null) {
sm.checkPropertyAccess(key);
}
return props.getProperty(key, def);
}
/**
* Sets the system property indicated by the specified key.
*
* First, if a security manager exists, its
* {@code SecurityManager.checkPermission} method
* is called with a {@code PropertyPermission(key, "write")}
* permission. This may result in a SecurityException being thrown.
* If no exception is thrown, the specified property is set to the given
* value.
*
* @apiNote
* <strong>Changing a standard system property may have unpredictable results
* unless otherwise specified</strong>.
* See {@linkplain #getProperties getProperties} for details.
*
* @param key the name of the system property.
* @param value the value of the system property.
* @return the previous value of the system property,
* or {@code null} if it did not have one.
*
* @throws SecurityException if a security manager exists and its
* {@code checkPermission} method doesn't allow
* setting of the specified property.
* @throws NullPointerException if {@code key} or
* {@code value} is {@code null}.
* @throws IllegalArgumentException if {@code key} is empty.
* @see #getProperty
* @see java.lang.System#getProperty(java.lang.String)
* @see java.lang.System#getProperty(java.lang.String, java.lang.String)
* @see java.util.PropertyPermission
* @see SecurityManager#checkPermission
* @since 1.2
*/
public static String setProperty(String key, String value) {
checkKey(key);
SecurityManager sm = getSecurityManager();
if (sm != null) {
sm.checkPermission(new PropertyPermission(key,
SecurityConstants.PROPERTY_WRITE_ACTION));
}
return (String) props.setProperty(key, value);
}
/**
* Removes the system property indicated by the specified key.
*
* First, if a security manager exists, its
* {@code SecurityManager.checkPermission} method
* is called with a {@code PropertyPermission(key, "write")}
* permission. This may result in a SecurityException being thrown.
* If no exception is thrown, the specified property is removed.
*
* @apiNote
* <strong>Changing a standard system property may have unpredictable results
* unless otherwise specified</strong>.
* See {@linkplain #getProperties getProperties} method for details.
*
* @param key the name of the system property to be removed.
* @return the previous string value of the system property,
* or {@code null} if there was no property with that key.
*
* @throws SecurityException if a security manager exists and its
* {@code checkPropertyAccess} method doesn't allow
* access to the specified system property.
* @throws NullPointerException if {@code key} is {@code null}.
* @throws IllegalArgumentException if {@code key} is empty.
* @see #getProperty
* @see #setProperty
* @see java.util.Properties
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkPropertiesAccess()
* @since 1.5
*/
public static String clearProperty(String key) {
checkKey(key);
SecurityManager sm = getSecurityManager();
if (sm != null) {
sm.checkPermission(new PropertyPermission(key, "write"));
}
return (String) props.remove(key);
}
private static void checkKey(String key) {
if (key == null) {
throw new NullPointerException("key can't be null");
}
if (key.equals("")) {
throw new IllegalArgumentException("key can't be empty");
}
}
/**
* Gets the value of the specified environment variable. An
* environment variable is a system-dependent external named
* value.
*
* <p>If a security manager exists, its
* {@link SecurityManager#checkPermission checkPermission}
* method is called with a
* {@link RuntimePermission RuntimePermission("getenv."+name)}
* permission. This may result in a {@link SecurityException}
* being thrown. If no exception is thrown the value of the
* variable {@code name} is returned.
*
* <p><a id="EnvironmentVSSystemProperties"><i>System
* properties</i> and <i>environment variables</i></a> are both
* conceptually mappings between names and values. Both
* mechanisms can be used to pass user-defined information to a
* Java process. Environment variables have a more global effect,
* because they are visible to all descendants of the process
* which defines them, not just the immediate Java subprocess.
* They can have subtly different semantics, such as case
* insensitivity, on different operating systems. For these
* reasons, environment variables are more likely to have
* unintended side effects. It is best to use system properties
* where possible. Environment variables should be used when a
* global effect is desired, or when an external system interface
* requires an environment variable (such as {@code PATH}).
*
* <p>On UNIX systems the alphabetic case of {@code name} is
* typically significant, while on Microsoft Windows systems it is
* typically not. For example, the expression
* {@code System.getenv("FOO").equals(System.getenv("foo"))}
* is likely to be true on Microsoft Windows.
*
* @param name the name of the environment variable
* @return the string value of the variable, or {@code null}
* if the variable is not defined in the system environment
* @throws NullPointerException if {@code name} is {@code null}
* @throws SecurityException
* if a security manager exists and its
* {@link SecurityManager#checkPermission checkPermission}
* method doesn't allow access to the environment variable
* {@code name}
* @see #getenv()
* @see ProcessBuilder#environment()
*/
public static String getenv(String name) {
SecurityManager sm = getSecurityManager();
if (sm != null) {
sm.checkPermission(new RuntimePermission("getenv."+name));
}
return ProcessEnvironment.getenv(name);
}
/**
* Returns an unmodifiable string map view of the current system environment.
* The environment is a system-dependent mapping from names to
* values which is passed from parent to child processes.
*
* <p>If the system does not support environment variables, an
* empty map is returned.
*
* <p>The returned map will never contain null keys or values.
* Attempting to query the presence of a null key or value will
* throw a {@link NullPointerException}. Attempting to query
* the presence of a key or value which is not of type
* {@link String} will throw a {@link ClassCastException}.
*
* <p>The returned map and its collection views may not obey the
* general contract of the {@link Object#equals} and
* {@link Object#hashCode} methods.
*
* <p>The returned map is typically case-sensitive on all platforms.
*
* <p>If a security manager exists, its
* {@link SecurityManager#checkPermission checkPermission}
* method is called with a
* {@link RuntimePermission RuntimePermission("getenv.*")} permission.
* This may result in a {@link SecurityException} being thrown.
*
* <p>When passing information to a Java subprocess,
* <a href=#EnvironmentVSSystemProperties>system properties</a>
* are generally preferred over environment variables.
*
* @return the environment as a map of variable names to values
* @throws SecurityException
* if a security manager exists and its
* {@link SecurityManager#checkPermission checkPermission}
* method doesn't allow access to the process environment
* @see #getenv(String)
* @see ProcessBuilder#environment()
* @since 1.5
*/
public static java.util.Map<String,String> getenv() {
SecurityManager sm = getSecurityManager();
if (sm != null) {
sm.checkPermission(new RuntimePermission("getenv.*"));
}
return ProcessEnvironment.getenv();
}
/**
* {@code System.Logger} instances log messages that will be
* routed to the underlying logging framework the {@link System.LoggerFinder
* LoggerFinder} uses.
*
* {@code System.Logger} instances are typically obtained from
* the {@link java.lang.System System} class, by calling
* {@link java.lang.System#getLogger(java.lang.String) System.getLogger(loggerName)}
* or {@link java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
* System.getLogger(loggerName, bundle)}.
*
* @see java.lang.System#getLogger(java.lang.String)
* @see java.lang.System#getLogger(java.lang.String, java.util.ResourceBundle)
* @see java.lang.System.LoggerFinder
*
* @since 9
*/
public interface Logger {
/**
* System {@linkplain Logger loggers} levels.
*
* A level has a {@linkplain #getName() name} and {@linkplain
* #getSeverity() severity}.
* Level values are {@link #ALL}, {@link #TRACE}, {@link #DEBUG},
* {@link #INFO}, {@link #WARNING}, {@link #ERROR}, {@link #OFF},
* by order of increasing severity.
* <br>
* {@link #ALL} and {@link #OFF}
* are simple markers with severities mapped respectively to
* {@link java.lang.Integer#MIN_VALUE Integer.MIN_VALUE} and
* {@link java.lang.Integer#MAX_VALUE Integer.MAX_VALUE}.
* <p>
* <b>Severity values and Mapping to {@code java.util.logging.Level}.</b>
* <p>
* {@linkplain System.Logger.Level System logger levels} are mapped to
* {@linkplain java.util.logging.Level java.util.logging levels}
* of corresponding severity.
* <br>The mapping is as follows:
* <br><br>
* <table class="striped">
* <caption>System.Logger Severity Level Mapping</caption>
* <thead>
* <tr><th scope="col">System.Logger Levels</th>
* <th scope="col">java.util.logging Levels</th>
* </thead>
* <tbody>
* <tr><th scope="row">{@link Logger.Level#ALL ALL}</th>
* <td>{@link java.util.logging.Level#ALL ALL}</td>
* <tr><th scope="row">{@link Logger.Level#TRACE TRACE}</th>
* <td>{@link java.util.logging.Level#FINER FINER}</td>
* <tr><th scope="row">{@link Logger.Level#DEBUG DEBUG}</th>
* <td>{@link java.util.logging.Level#FINE FINE}</td>
* <tr><th scope="row">{@link Logger.Level#INFO INFO}</th>
* <td>{@link java.util.logging.Level#INFO INFO}</td>
* <tr><th scope="row">{@link Logger.Level#WARNING WARNING}</th>
* <td>{@link java.util.logging.Level#WARNING WARNING}</td>
* <tr><th scope="row">{@link Logger.Level#ERROR ERROR}</th>
* <td>{@link java.util.logging.Level#SEVERE SEVERE}</td>
* <tr><th scope="row">{@link Logger.Level#OFF OFF}</th>
* <td>{@link java.util.logging.Level#OFF OFF}</td>
* </tbody>
* </table>
*
* @since 9
*
* @see java.lang.System.LoggerFinder
* @see java.lang.System.Logger
*/
public enum Level {
// for convenience, we're reusing java.util.logging.Level int values
// the mapping logic in sun.util.logging.PlatformLogger depends
// on this.
/**
* A marker to indicate that all levels are enabled.
* This level {@linkplain #getSeverity() severity} is
* {@link Integer#MIN_VALUE}.
*/
ALL(Integer.MIN_VALUE), // typically mapped to/from j.u.l.Level.ALL
/**
* {@code TRACE} level: usually used to log diagnostic information.
* This level {@linkplain #getSeverity() severity} is
* {@code 400}.
*/
TRACE(400), // typically mapped to/from j.u.l.Level.FINER
/**
* {@code DEBUG} level: usually used to log debug information traces.
* This level {@linkplain #getSeverity() severity} is
* {@code 500}.
*/
DEBUG(500), // typically mapped to/from j.u.l.Level.FINEST/FINE/CONFIG
/**
* {@code INFO} level: usually used to log information messages.
* This level {@linkplain #getSeverity() severity} is
* {@code 800}.
*/
INFO(800), // typically mapped to/from j.u.l.Level.INFO
/**
* {@code WARNING} level: usually used to log warning messages.
* This level {@linkplain #getSeverity() severity} is
* {@code 900}.
*/
WARNING(900), // typically mapped to/from j.u.l.Level.WARNING
/**
* {@code ERROR} level: usually used to log error messages.
* This level {@linkplain #getSeverity() severity} is
* {@code 1000}.
*/
ERROR(1000), // typically mapped to/from j.u.l.Level.SEVERE
/**
* A marker to indicate that all levels are disabled.
* This level {@linkplain #getSeverity() severity} is
* {@link Integer#MAX_VALUE}.
*/
OFF(Integer.MAX_VALUE); // typically mapped to/from j.u.l.Level.OFF
private final int severity;
private Level(int severity) {
this.severity = severity;
}
/**
* Returns the name of this level.
* @return this level {@linkplain #name()}.
*/
public final String getName() {
return name();
}
/**
* Returns the severity of this level.
* A higher severity means a more severe condition.
* @return this level severity.
*/
public final int getSeverity() {
return severity;
}
}
/**
* Returns the name of this logger.
*
* @return the logger name.
*/
public String getName();
/**
* Checks if a message of the given level would be logged by
* this logger.
*
* @param level the log message level.
* @return {@code true} if the given log message level is currently
* being logged.
*
* @throws NullPointerException if {@code level} is {@code null}.
*/
public boolean isLoggable(Level level);
/**
* Logs a message.
*
* @implSpec The default implementation for this method calls
* {@code this.log(level, (ResourceBundle)null, msg, (Object[])null);}
*
* @param level the log message level.
* @param msg the string message (or a key in the message catalog, if
* this logger is a {@link
* LoggerFinder#getLocalizedLogger(java.lang.String,
* java.util.ResourceBundle, java.lang.Module) localized logger});
* can be {@code null}.
*
* @throws NullPointerException if {@code level} is {@code null}.
*/
public default void log(Level level, String msg) {
log(level, (ResourceBundle) null, msg, (Object[]) null);
}
/**
* Logs a lazily supplied message.
*
* If the logger is currently enabled for the given log message level
* then a message is logged that is the result produced by the
* given supplier function. Otherwise, the supplier is not operated on.
*
* @implSpec When logging is enabled for the given level, the default
* implementation for this method calls
* {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), (Object[])null);}
*
* @param level the log message level.
* @param msgSupplier a supplier function that produces a message.
*
* @throws NullPointerException if {@code level} is {@code null},
* or {@code msgSupplier} is {@code null}.
*/
public default void log(Level level, Supplier<String> msgSupplier) {
Objects.requireNonNull(msgSupplier);
if (isLoggable(Objects.requireNonNull(level))) {
log(level, (ResourceBundle) null, msgSupplier.get(), (Object[]) null);
}
}
/**
* Logs a message produced from the given object.
*
* If the logger is currently enabled for the given log message level then
* a message is logged that, by default, is the result produced from
* calling toString on the given object.
* Otherwise, the object is not operated on.
*
* @implSpec When logging is enabled for the given level, the default
* implementation for this method calls
* {@code this.log(level, (ResourceBundle)null, obj.toString(), (Object[])null);}
*
* @param level the log message level.
* @param obj the object to log.
*
* @throws NullPointerException if {@code level} is {@code null}, or
* {@code obj} is {@code null}.
*/
public default void log(Level level, Object obj) {
Objects.requireNonNull(obj);
if (isLoggable(Objects.requireNonNull(level))) {
this.log(level, (ResourceBundle) null, obj.toString(), (Object[]) null);
}
}
/**
* Logs a message associated with a given throwable.
*
* @implSpec The default implementation for this method calls
* {@code this.log(level, (ResourceBundle)null, msg, thrown);}
*
* @param level the log message level.
* @param msg the string message (or a key in the message catalog, if
* this logger is a {@link
* LoggerFinder#getLocalizedLogger(java.lang.String,
* java.util.ResourceBundle, java.lang.Module) localized logger});
* can be {@code null}.
* @param thrown a {@code Throwable} associated with the log message;
* can be {@code null}.
*
* @throws NullPointerException if {@code level} is {@code null}.
*/
public default void log(Level level, String msg, Throwable thrown) {
this.log(level, null, msg, thrown);
}
/**
* Logs a lazily supplied message associated with a given throwable.
*
* If the logger is currently enabled for the given log message level
* then a message is logged that is the result produced by the
* given supplier function. Otherwise, the supplier is not operated on.
*
* @implSpec When logging is enabled for the given level, the default
* implementation for this method calls
* {@code this.log(level, (ResourceBundle)null, msgSupplier.get(), thrown);}
*
* @param level one of the log message level identifiers.
* @param msgSupplier a supplier function that produces a message.
* @param thrown a {@code Throwable} associated with log message;
* can be {@code null}.
*
* @throws NullPointerException if {@code level} is {@code null}, or
* {@code msgSupplier} is {@code null}.
*/
public default void log(Level level, Supplier<String> msgSupplier,
Throwable thrown) {
Objects.requireNonNull(msgSupplier);
if (isLoggable(Objects.requireNonNull(level))) {
this.log(level, null, msgSupplier.get(), thrown);
}
}
/**
* Logs a message with an optional list of parameters.
*
* @implSpec The default implementation for this method calls
* {@code this.log(level, (ResourceBundle)null, format, params);}
*
* @param level one of the log message level identifiers.
* @param format the string message format in {@link
* java.text.MessageFormat} format, (or a key in the message
* catalog, if this logger is a {@link
* LoggerFinder#getLocalizedLogger(java.lang.String,
* java.util.ResourceBundle, java.lang.Module) localized logger});
* can be {@code null}.
* @param params an optional list of parameters to the message (may be
* none).
*
* @throws NullPointerException if {@code level} is {@code null}.
*/
public default void log(Level level, String format, Object... params) {
this.log(level, null, format, params);
}
/**
* Logs a localized message associated with a given throwable.
*
* If the given resource bundle is non-{@code null}, the {@code msg}
* string is localized using the given resource bundle.
* Otherwise the {@code msg} string is not localized.
*
* @param level the log message level.
* @param bundle a resource bundle to localize {@code msg}; can be
* {@code null}.
* @param msg the string message (or a key in the message catalog,
* if {@code bundle} is not {@code null}); can be {@code null}.
* @param thrown a {@code Throwable} associated with the log message;
* can be {@code null}.
*
* @throws NullPointerException if {@code level} is {@code null}.
*/
public void log(Level level, ResourceBundle bundle, String msg,
Throwable thrown);
/**
* Logs a message with resource bundle and an optional list of
* parameters.
*
* If the given resource bundle is non-{@code null}, the {@code format}
* string is localized using the given resource bundle.
* Otherwise the {@code format} string is not localized.
*
* @param level the log message level.
* @param bundle a resource bundle to localize {@code format}; can be
* {@code null}.
* @param format the string message format in {@link
* java.text.MessageFormat} format, (or a key in the message
* catalog if {@code bundle} is not {@code null}); can be {@code null}.
* @param params an optional list of parameters to the message (may be
* none).
*
* @throws NullPointerException if {@code level} is {@code null}.
*/
public void log(Level level, ResourceBundle bundle, String format,
Object... params);
}
/**
* The {@code LoggerFinder} service is responsible for creating, managing,
* and configuring loggers to the underlying framework it uses.
*
* A logger finder is a concrete implementation of this class that has a
* zero-argument constructor and implements the abstract methods defined
* by this class.
* The loggers returned from a logger finder are capable of routing log
* messages to the logging backend this provider supports.
* A given invocation of the Java Runtime maintains a single
* system-wide LoggerFinder instance that is loaded as follows:
* <ul>
* <li>First it finds any custom {@code LoggerFinder} provider
* using the {@link java.util.ServiceLoader} facility with the
* {@linkplain ClassLoader#getSystemClassLoader() system class
* loader}.</li>
* <li>If no {@code LoggerFinder} provider is found, the system default
* {@code LoggerFinder} implementation will be used.</li>
* </ul>
* <p>
* An application can replace the logging backend
* <i>even when the java.logging module is present</i>, by simply providing
* and declaring an implementation of the {@link LoggerFinder} service.
* <p>
* <b>Default Implementation</b>
* <p>
* The system default {@code LoggerFinder} implementation uses
* {@code java.util.logging} as the backend framework when the
* {@code java.logging} module is present.
* It returns a {@linkplain System.Logger logger} instance
* that will route log messages to a {@link java.util.logging.Logger
* java.util.logging.Logger}. Otherwise, if {@code java.logging} is not
* present, the default implementation will return a simple logger
* instance that will route log messages of {@code INFO} level and above to
* the console ({@code System.err}).
* <p>
* <b>Logging Configuration</b>
* <p>
* {@linkplain Logger Logger} instances obtained from the
* {@code LoggerFinder} factory methods are not directly configurable by
* the application. Configuration is the responsibility of the underlying
* logging backend, and usually requires using APIs specific to that backend.
* <p>For the default {@code LoggerFinder} implementation
* using {@code java.util.logging} as its backend, refer to
* {@link java.util.logging java.util.logging} for logging configuration.
* For the default {@code LoggerFinder} implementation returning simple loggers
* when the {@code java.logging} module is absent, the configuration
* is implementation dependent.
* <p>
* Usually an application that uses a logging framework will log messages
* through a logger facade defined (or supported) by that framework.
* Applications that wish to use an external framework should log
* through the facade associated with that framework.
* <p>
* A system class that needs to log messages will typically obtain
* a {@link System.Logger} instance to route messages to the logging
* framework selected by the application.
* <p>
* Libraries and classes that only need loggers to produce log messages
* should not attempt to configure loggers by themselves, as that
* would make them dependent from a specific implementation of the
* {@code LoggerFinder} service.
* <p>
* In addition, when a security manager is present, loggers provided to
* system classes should not be directly configurable through the logging
* backend without requiring permissions.
* <br>
* It is the responsibility of the provider of
* the concrete {@code LoggerFinder} implementation to ensure that
* these loggers are not configured by untrusted code without proper
* permission checks, as configuration performed on such loggers usually
* affects all applications in the same Java Runtime.
* <p>
* <b>Message Levels and Mapping to backend levels</b>
* <p>
* A logger finder is responsible for mapping from a {@code
* System.Logger.Level} to a level supported by the logging backend it uses.
* <br>The default LoggerFinder using {@code java.util.logging} as the backend
* maps {@code System.Logger} levels to
* {@linkplain java.util.logging.Level java.util.logging} levels
* of corresponding severity - as described in {@link Logger.Level
* Logger.Level}.
*
* @see java.lang.System
* @see java.lang.System.Logger
*
* @since 9
*/
public static abstract class LoggerFinder {
/**
* The {@code RuntimePermission("loggerFinder")} is
* necessary to subclass and instantiate the {@code LoggerFinder} class,
* as well as to obtain loggers from an instance of that class.
*/
static final RuntimePermission LOGGERFINDER_PERMISSION =
new RuntimePermission("loggerFinder");
/**
* Creates a new instance of {@code LoggerFinder}.
*
* @implNote It is recommended that a {@code LoggerFinder} service
* implementation does not perform any heavy initialization in its
* constructor, in order to avoid possible risks of deadlock or class
* loading cycles during the instantiation of the service provider.
*
* @throws SecurityException if a security manager is present and its
* {@code checkPermission} method doesn't allow the
* {@code RuntimePermission("loggerFinder")}.
*/
protected LoggerFinder() {
this(checkPermission());
}
private LoggerFinder(Void unused) {
// nothing to do.
}
private static Void checkPermission() {
final SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(LOGGERFINDER_PERMISSION);
}
return null;
}
/**
* Returns an instance of {@link Logger Logger}
* for the given {@code module}.
*
* @param name the name of the logger.
* @param module the module for which the logger is being requested.
*
* @return a {@link Logger logger} suitable for use within the given
* module.
* @throws NullPointerException if {@code name} is {@code null} or
* {@code module} is {@code null}.
* @throws SecurityException if a security manager is present and its
* {@code checkPermission} method doesn't allow the
* {@code RuntimePermission("loggerFinder")}.
*/
public abstract Logger getLogger(String name, Module module);
/**
* Returns a localizable instance of {@link Logger Logger}
* for the given {@code module}.
* The returned logger will use the provided resource bundle for
* message localization.
*
* @implSpec By default, this method calls {@link
* #getLogger(java.lang.String, java.lang.Module)
* this.getLogger(name, module)} to obtain a logger, then wraps that
* logger in a {@link Logger} instance where all methods that do not
* take a {@link ResourceBundle} as parameter are redirected to one
* which does - passing the given {@code bundle} for
* localization. So for instance, a call to {@link
* Logger#log(Logger.Level, String) Logger.log(Level.INFO, msg)}
* will end up as a call to {@link
* Logger#log(Logger.Level, ResourceBundle, String, Object...)
* Logger.log(Level.INFO, bundle, msg, (Object[])null)} on the wrapped
* logger instance.
* Note however that by default, string messages returned by {@link
* java.util.function.Supplier Supplier&lt;String&gt;} will not be
* localized, as it is assumed that such strings are messages which are
* already constructed, rather than keys in a resource bundle.
* <p>
* An implementation of {@code LoggerFinder} may override this method,
* for example, when the underlying logging backend provides its own
* mechanism for localizing log messages, then such a
* {@code LoggerFinder} would be free to return a logger
* that makes direct use of the mechanism provided by the backend.
*
* @param name the name of the logger.
* @param bundle a resource bundle; can be {@code null}.
* @param module the module for which the logger is being requested.
* @return an instance of {@link Logger Logger} which will use the
* provided resource bundle for message localization.
*
* @throws NullPointerException if {@code name} is {@code null} or
* {@code module} is {@code null}.
* @throws SecurityException if a security manager is present and its
* {@code checkPermission} method doesn't allow the
* {@code RuntimePermission("loggerFinder")}.
*/
public Logger getLocalizedLogger(String name, ResourceBundle bundle,
Module module) {
return new LocalizedLoggerWrapper<>(getLogger(name, module), bundle);
}
/**
* Returns the {@code LoggerFinder} instance. There is one
* single system-wide {@code LoggerFinder} instance in
* the Java Runtime. See the class specification of how the
* {@link LoggerFinder LoggerFinder} implementation is located and
* loaded.
* @return the {@link LoggerFinder LoggerFinder} instance.
* @throws SecurityException if a security manager is present and its
* {@code checkPermission} method doesn't allow the
* {@code RuntimePermission("loggerFinder")}.
*/
public static LoggerFinder getLoggerFinder() {
final SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(LOGGERFINDER_PERMISSION);
}
return accessProvider();
}
private static volatile LoggerFinder service;
static LoggerFinder accessProvider() {
// We do not need to synchronize: LoggerFinderLoader will
// always return the same instance, so if we don't have it,
// just fetch it again.
if (service == null) {
PrivilegedAction<LoggerFinder> pa =
() -> LoggerFinderLoader.getLoggerFinder();
service = AccessController.doPrivileged(pa, null,
LOGGERFINDER_PERMISSION);
}
return service;
}
}
/**
* Returns an instance of {@link Logger Logger} for the caller's
* use.
*
* @implSpec
* Instances returned by this method route messages to loggers
* obtained by calling {@link LoggerFinder#getLogger(java.lang.String,
* java.lang.Module) LoggerFinder.getLogger(name, module)}, where
* {@code module} is the caller's module.
* In cases where {@code System.getLogger} is called from a context where
* there is no caller frame on the stack (e.g when called directly
* from a JNI attached thread), {@code IllegalCallerException} is thrown.
* To obtain a logger in such a context, use an auxiliary class that will
* implicitly be identified as the caller, or use the system {@link
* LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
* Note that doing the latter may eagerly initialize the underlying
* logging system.
*
* @apiNote
* This method may defer calling the {@link
* LoggerFinder#getLogger(java.lang.String, java.lang.Module)
* LoggerFinder.getLogger} method to create an actual logger supplied by
* the logging backend, for instance, to allow loggers to be obtained during
* the system initialization time.
*
* @param name the name of the logger.
* @return an instance of {@link Logger} that can be used by the calling
* class.
* @throws NullPointerException if {@code name} is {@code null}.
* @throws IllegalCallerException if there is no Java caller frame on the
* stack.
*
* @since 9
*/
@CallerSensitive
public static Logger getLogger(String name) {
Objects.requireNonNull(name);
final Class<?> caller = Reflection.getCallerClass();
if (caller == null) {
throw new IllegalCallerException("no caller frame");
}
return LazyLoggers.getLogger(name, caller.getModule());
}
/**
* Returns a localizable instance of {@link Logger
* Logger} for the caller's use.
* The returned logger will use the provided resource bundle for message
* localization.
*
* @implSpec
* The returned logger will perform message localization as specified
* by {@link LoggerFinder#getLocalizedLogger(java.lang.String,
* java.util.ResourceBundle, java.lang.Module)
* LoggerFinder.getLocalizedLogger(name, bundle, module)}, where
* {@code module} is the caller's module.
* In cases where {@code System.getLogger} is called from a context where
* there is no caller frame on the stack (e.g when called directly
* from a JNI attached thread), {@code IllegalCallerException} is thrown.
* To obtain a logger in such a context, use an auxiliary class that
* will implicitly be identified as the caller, or use the system {@link
* LoggerFinder#getLoggerFinder() LoggerFinder} to obtain a logger instead.
* Note that doing the latter may eagerly initialize the underlying
* logging system.
*
* @apiNote
* This method is intended to be used after the system is fully initialized.
* This method may trigger the immediate loading and initialization
* of the {@link LoggerFinder} service, which may cause issues if the
* Java Runtime is not ready to initialize the concrete service
* implementation yet.
* System classes which may be loaded early in the boot sequence and
* need to log localized messages should create a logger using
* {@link #getLogger(java.lang.String)} and then use the log methods that
* take a resource bundle as parameter.
*
* @param name the name of the logger.
* @param bundle a resource bundle.
* @return an instance of {@link Logger} which will use the provided
* resource bundle for message localization.
* @throws NullPointerException if {@code name} is {@code null} or
* {@code bundle} is {@code null}.
* @throws IllegalCallerException if there is no Java caller frame on the
* stack.
*
* @since 9
*/
@CallerSensitive
public static Logger getLogger(String name, ResourceBundle bundle) {
final ResourceBundle rb = Objects.requireNonNull(bundle);
Objects.requireNonNull(name);
final Class<?> caller = Reflection.getCallerClass();
if (caller == null) {
throw new IllegalCallerException("no caller frame");
}
final SecurityManager sm = System.getSecurityManager();
// We don't use LazyLoggers if a resource bundle is specified.
// Bootstrap sensitive classes in the JDK do not use resource bundles
// when logging. This could be revisited later, if it needs to.
if (sm != null) {
final PrivilegedAction<Logger> pa =
() -> LoggerFinder.accessProvider()
.getLocalizedLogger(name, rb, caller.getModule());
return AccessController.doPrivileged(pa, null,
LoggerFinder.LOGGERFINDER_PERMISSION);
}
return LoggerFinder.accessProvider()
.getLocalizedLogger(name, rb, caller.getModule());
}
/**
* Terminates the currently running Java Virtual Machine. The
* argument serves as a status code; by convention, a nonzero status
* code indicates abnormal termination.
* <p>
* This method calls the {@code exit} method in class
* {@code Runtime}. This method never returns normally.
* <p>
* The call {@code System.exit(n)} is effectively equivalent to
* the call:
* <blockquote><pre>
* Runtime.getRuntime().exit(n)
* </pre></blockquote>
*
* @param status exit status.
* @throws SecurityException
* if a security manager exists and its {@code checkExit}
* method doesn't allow exit with the specified status.
* @see java.lang.Runtime#exit(int)
*/
public static void exit(int status) {
Runtime.getRuntime().exit(status);
}
/**
* Runs the garbage collector.
*
* Calling the {@code gc} method suggests that the Java Virtual
* Machine expend effort toward recycling unused objects in order to
* make the memory they currently occupy available for quick reuse.
* When control returns from the method call, the Java Virtual
* Machine has made a best effort to reclaim space from all discarded
* objects.
* <p>
* The call {@code System.gc()} is effectively equivalent to the
* call:
* <blockquote><pre>
* Runtime.getRuntime().gc()
* </pre></blockquote>
*
* @see java.lang.Runtime#gc()
*/
public static void gc() {
Runtime.getRuntime().gc();
}
/**
* Runs the finalization methods of any objects pending finalization.
*
* Calling this method suggests that the Java Virtual Machine expend
* effort toward running the {@code finalize} methods of objects
* that have been found to be discarded but whose {@code finalize}
* methods have not yet been run. When control returns from the
* method call, the Java Virtual Machine has made a best effort to
* complete all outstanding finalizations.
* <p>
* The call {@code System.runFinalization()} is effectively
* equivalent to the call:
* <blockquote><pre>
* Runtime.getRuntime().runFinalization()
* </pre></blockquote>
*
* @see java.lang.Runtime#runFinalization()
*/
public static void runFinalization() {
Runtime.getRuntime().runFinalization();
}
/**
* Loads the native library specified by the filename argument. The filename
* argument must be an absolute path name.
*
* If the filename argument, when stripped of any platform-specific library
* prefix, path, and file extension, indicates a library whose name is,
* for example, L, and a native library called L is statically linked
* with the VM, then the JNI_OnLoad_L function exported by the library
* is invoked rather than attempting to load a dynamic library.
* A filename matching the argument does not have to exist in the
* file system.
* See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
* for more details.
*
* Otherwise, the filename argument is mapped to a native library image in
* an implementation-dependent manner.
*
* <p>
* The call {@code System.load(name)} is effectively equivalent
* to the call:
* <blockquote><pre>
* Runtime.getRuntime().load(name)
* </pre></blockquote>
*
* @param filename the file to load.
* @throws SecurityException if a security manager exists and its
* {@code checkLink} method doesn't allow
* loading of the specified dynamic library
* @throws UnsatisfiedLinkError if either the filename is not an
* absolute path name, the native library is not statically
* linked with the VM, or the library cannot be mapped to
* a native library image by the host system.
* @throws NullPointerException if {@code filename} is {@code null}
* @see java.lang.Runtime#load(java.lang.String)
* @see java.lang.SecurityManager#checkLink(java.lang.String)
*/
@CallerSensitive
public static void load(String filename) {
Runtime.getRuntime().load0(Reflection.getCallerClass(), filename);
}
/**
* Loads the native library specified by the {@code libname}
* argument. The {@code libname} argument must not contain any platform
* specific prefix, file extension or path. If a native library
* called {@code libname} is statically linked with the VM, then the
* JNI_OnLoad_{@code libname} function exported by the library is invoked.
* See the <a href="{@docRoot}/../specs/jni/index.html"> JNI Specification</a>
* for more details.
*
* Otherwise, the libname argument is loaded from a system library
* location and mapped to a native library image in an implementation-
* dependent manner.
* <p>
* The call {@code System.loadLibrary(name)} is effectively
* equivalent to the call
* <blockquote><pre>
* Runtime.getRuntime().loadLibrary(name)
* </pre></blockquote>
*
* @param libname the name of the library.
* @throws SecurityException if a security manager exists and its
* {@code checkLink} method doesn't allow
* loading of the specified dynamic library
* @throws UnsatisfiedLinkError if either the libname argument
* contains a file path, the native library is not statically
* linked with the VM, or the library cannot be mapped to a
* native library image by the host system.
* @throws NullPointerException if {@code libname} is {@code null}
* @see java.lang.Runtime#loadLibrary(java.lang.String)
* @see java.lang.SecurityManager#checkLink(java.lang.String)
*/
@CallerSensitive
public static void loadLibrary(String libname) {
Runtime.getRuntime().loadLibrary0(Reflection.getCallerClass(), libname);
}
/**
* Maps a library name into a platform-specific string representing
* a native library.
*
* @param libname the name of the library.
* @return a platform-dependent native library name.
* @throws NullPointerException if {@code libname} is {@code null}
* @see java.lang.System#loadLibrary(java.lang.String)
* @see java.lang.ClassLoader#findLibrary(java.lang.String)
* @since 1.2
*/
public static native String mapLibraryName(String libname);
/**
* Create PrintStream for stdout/err based on encoding.
*/
private static PrintStream newPrintStream(FileOutputStream fos, String enc) {
if (enc != null) {
try {
return new PrintStream(new BufferedOutputStream(fos, 128), true, enc);
} catch (UnsupportedEncodingException uee) {}
}
return new PrintStream(new BufferedOutputStream(fos, 128), true);
}
/**
* Logs an exception/error at initialization time to stdout or stderr.
*
* @param printToStderr to print to stderr rather than stdout
* @param printStackTrace to print the stack trace
* @param msg the message to print before the exception, can be {@code null}
* @param e the exception or error
*/
private static void logInitException(boolean printToStderr,
boolean printStackTrace,
String msg,
Throwable e) {
if (VM.initLevel() < 1) {
throw new InternalError("system classes not initialized");
}
PrintStream log = (printToStderr) ? err : out;
if (msg != null) {
log.println(msg);
}
if (printStackTrace) {
e.printStackTrace(log);
} else {
log.println(e);
for (Throwable suppressed : e.getSuppressed()) {
log.println("Suppressed: " + suppressed);
}
Throwable cause = e.getCause();
if (cause != null) {
log.println("Caused by: " + cause);
}
}
}
/**
* Initialize the system class. Called after thread initialization.
*/
private static void initPhase1() {
// VM might invoke JNU_NewStringPlatform() to set those encoding
// sensitive properties (user.home, user.name, boot.class.path, etc.)
// during "props" initialization, in which it may need access, via
// System.getProperty(), to the related system encoding property that
// have been initialized (put into "props") at early stage of the
// initialization. So make sure the "props" is available at the
// very beginning of the initialization and all system properties to
// be put into it directly.
props = new Properties(84);
initProperties(props); // initialized by the VM
// There are certain system configurations that may be controlled by
// VM options such as the maximum amount of direct memory and
// Integer cache size used to support the object identity semantics
// of autoboxing. Typically, the library will obtain these values
// from the properties set by the VM. If the properties are for
// internal implementation use only, these properties should be
// removed from the system properties.
//
// See java.lang.Integer.IntegerCache and the
// VM.saveAndRemoveProperties method for example.
//
// Save a private copy of the system properties object that
// can only be accessed by the internal implementation. Remove
// certain system properties that are not intended for public access.
VM.saveAndRemoveProperties(props);
lineSeparator = props.getProperty("line.separator");
StaticProperty.javaHome(); // Load StaticProperty to cache the property values
VersionProps.init();
FileInputStream fdIn = new FileInputStream(FileDescriptor.in);
FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out);
FileOutputStream fdErr = new FileOutputStream(FileDescriptor.err);
setIn0(new BufferedInputStream(fdIn));
setOut0(newPrintStream(fdOut, props.getProperty("sun.stdout.encoding")));
setErr0(newPrintStream(fdErr, props.getProperty("sun.stderr.encoding")));
// Setup Java signal handlers for HUP, TERM, and INT (where available).
Terminator.setup();
// Initialize any miscellaneous operating system settings that need to be
// set for the class libraries. Currently this is no-op everywhere except
// for Windows where the process-wide error mode is set before the java.io
// classes are used.
VM.initializeOSEnvironment();
// The main thread is not added to its thread group in the same
// way as other threads; we must do it ourselves here.
Thread current = Thread.currentThread();
current.getThreadGroup().add(current);
// register shared secrets
setJavaLangAccess();
ClassLoader.initLibraryPaths();
// Subsystems that are invoked during initialization can invoke
// VM.isBooted() in order to avoid doing things that should
// wait until the VM is fully initialized. The initialization level
// is incremented from 0 to 1 here to indicate the first phase of
// initialization has completed.
// IMPORTANT: Ensure that this remains the last initialization action!
VM.initLevel(1);
}
// @see #initPhase2()
static ModuleLayer bootLayer;
/*
* Invoked by VM. Phase 2 module system initialization.
* Only classes in java.base can be loaded in this phase.
*
* @param printToStderr print exceptions to stderr rather than stdout
* @param printStackTrace print stack trace when exception occurs
*
* @return JNI_OK for success, JNI_ERR for failure
*/
private static int initPhase2(boolean printToStderr, boolean printStackTrace) {
try {
bootLayer = ModuleBootstrap.boot();
} catch (Exception | Error e) {
logInitException(printToStderr, printStackTrace,
"Error occurred during initialization of boot layer", e);
return -1; // JNI_ERR
}
// module system initialized
VM.initLevel(2);
return 0; // JNI_OK
}
/*
* Invoked by VM. Phase 3 is the final system initialization:
* 1. set security manager
* 2. set system class loader
* 3. set TCCL
*
* This method must be called after the module system initialization.
* The security manager and system class loader may be custom class from
* the application classpath or modulepath.
*/
private static void initPhase3() {
// set security manager
String cn = System.getProperty("java.security.manager");
if (cn != null) {
if (cn.isEmpty() || "default".equals(cn)) {
System.setSecurityManager(new SecurityManager());
} else {
try {
Class<?> c = Class.forName(cn, false, ClassLoader.getBuiltinAppClassLoader());
Constructor<?> ctor = c.getConstructor();
// Must be a public subclass of SecurityManager with
// a public no-arg constructor
if (!SecurityManager.class.isAssignableFrom(c) ||
!Modifier.isPublic(c.getModifiers()) ||
!Modifier.isPublic(ctor.getModifiers())) {
throw new Error("Could not create SecurityManager: " + ctor.toString());
}
// custom security manager implementation may be in unnamed module
// or a named module but non-exported package
ctor.setAccessible(true);
SecurityManager sm = (SecurityManager) ctor.newInstance();
System.setSecurityManager(sm);
} catch (Exception e) {
throw new Error("Could not create SecurityManager", e);
}
}
}
// initializing the system class loader
VM.initLevel(3);
// system class loader initialized
ClassLoader scl = ClassLoader.initSystemClassLoader();
// set TCCL
Thread.currentThread().setContextClassLoader(scl);
// system is fully initialized
VM.initLevel(4);
}
private static void setJavaLangAccess() {
// Allow privileged classes outside of java.lang
SharedSecrets.setJavaLangAccess(new JavaLangAccess() {
public List<Method> getDeclaredPublicMethods(Class<?> klass, String name, Class<?>... parameterTypes) {
return klass.getDeclaredPublicMethods(name, parameterTypes);
}
public jdk.internal.reflect.ConstantPool getConstantPool(Class<?> klass) {
return klass.getConstantPool();
}
public boolean casAnnotationType(Class<?> klass, AnnotationType oldType, AnnotationType newType) {
return klass.casAnnotationType(oldType, newType);
}
public AnnotationType getAnnotationType(Class<?> klass) {
return klass.getAnnotationType();
}
public Map<Class<? extends Annotation>, Annotation> getDeclaredAnnotationMap(Class<?> klass) {
return klass.getDeclaredAnnotationMap();
}
public byte[] getRawClassAnnotations(Class<?> klass) {
return klass.getRawAnnotations();
}
public byte[] getRawClassTypeAnnotations(Class<?> klass) {
return klass.getRawTypeAnnotations();
}
public byte[] getRawExecutableTypeAnnotations(Executable executable) {
return Class.getExecutableTypeAnnotationBytes(executable);
}
public <E extends Enum<E>>
E[] getEnumConstantsShared(Class<E> klass) {
return klass.getEnumConstantsShared();
}
public void blockedOn(Interruptible b) {
Thread.blockedOn(b);
}
public void registerShutdownHook(int slot, boolean registerShutdownInProgress, Runnable hook) {
Shutdown.add(slot, registerShutdownInProgress, hook);
}
public Thread newThreadWithAcc(Runnable target, AccessControlContext acc) {
return new Thread(target, acc);
}
@SuppressWarnings("deprecation")
public void invokeFinalize(Object o) throws Throwable {
o.finalize();
}
public ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap(ClassLoader cl) {
return cl.createOrGetClassLoaderValueMap();
}
public Class<?> defineClass(ClassLoader loader, String name, byte[] b, ProtectionDomain pd, String source) {
return ClassLoader.defineClass1(loader, name, b, 0, b.length, pd, source);
}
public Class<?> findBootstrapClassOrNull(ClassLoader cl, String name) {
return cl.findBootstrapClassOrNull(name);
}
public Package definePackage(ClassLoader cl, String name, Module module) {
return cl.definePackage(name, module);
}
public String fastUUID(long lsb, long msb) {
return Long.fastUUID(lsb, msb);
}
public void addNonExportedPackages(ModuleLayer layer) {
SecurityManager.addNonExportedPackages(layer);
}
public void invalidatePackageAccessCache() {
SecurityManager.invalidatePackageAccessCache();
}
public Module defineModule(ClassLoader loader,
ModuleDescriptor descriptor,
URI uri) {
return new Module(null, loader, descriptor, uri);
}
public Module defineUnnamedModule(ClassLoader loader) {
return new Module(loader);
}
public void addReads(Module m1, Module m2) {
m1.implAddReads(m2);
}
public void addReadsAllUnnamed(Module m) {
m.implAddReadsAllUnnamed();
}
public void addExports(Module m, String pn, Module other) {
m.implAddExports(pn, other);
}
public void addExportsToAllUnnamed(Module m, String pn) {
m.implAddExportsToAllUnnamed(pn);
}
public void addOpens(Module m, String pn, Module other) {
m.implAddOpens(pn, other);
}
public void addOpensToAllUnnamed(Module m, String pn) {
m.implAddOpensToAllUnnamed(pn);
}
public void addOpensToAllUnnamed(Module m, Iterator<String> packages) {
m.implAddOpensToAllUnnamed(packages);
}
public void addUses(Module m, Class<?> service) {
m.implAddUses(service);
}
public boolean isReflectivelyExported(Module m, String pn, Module other) {
return m.isReflectivelyExported(pn, other);
}
public boolean isReflectivelyOpened(Module m, String pn, Module other) {
return m.isReflectivelyOpened(pn, other);
}
public ServicesCatalog getServicesCatalog(ModuleLayer layer) {
return layer.getServicesCatalog();
}
public Stream<ModuleLayer> layers(ModuleLayer layer) {
return layer.layers();
}
public Stream<ModuleLayer> layers(ClassLoader loader) {
return ModuleLayer.layers(loader);
}
public String newStringNoRepl(byte[] bytes, Charset cs) throws CharacterCodingException {
return StringCoding.newStringNoRepl(bytes, cs);
}
public byte[] getBytesNoRepl(String s, Charset cs) throws CharacterCodingException {
return StringCoding.getBytesNoRepl(s, cs);
}
public String newStringUTF8NoRepl(byte[] bytes, int off, int len) {
return StringCoding.newStringUTF8NoRepl(bytes, off, len);
}
public byte[] getBytesUTF8NoRepl(String s) {
return StringCoding.getBytesUTF8NoRepl(s);
}
});
}
}