Java example source code file (LogManager.java)
The LogManager.java Java example source code/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
* 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).
*
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package java.util.logging;
import java.io.*;
import java.util.*;
import java.security.*;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.beans.PropertyChangeListener;
import sun.misc.JavaAWTAccess;
import sun.misc.SharedSecrets;
/**
* There is a single global LogManager object that is used to
* maintain a set of shared state about Loggers and log services.
* <p>
* This LogManager object:
* <ul>
* <li> Manages a hierarchical namespace of Logger objects. All
* named Loggers are stored in this namespace.
* <li> Manages a set of logging control properties. These are
* simple key-value pairs that can be used by Handlers and
* other logging objects to configure themselves.
* </ul>
* <p>
* The global LogManager object can be retrieved using LogManager.getLogManager().
* The LogManager object is created during class initialization and
* cannot subsequently be changed.
* <p>
* At startup the LogManager class is located using the
* java.util.logging.manager system property.
* <p>
* The LogManager defines two optional system properties that allow control over
* the initial configuration:
* <ul>
* <li>"java.util.logging.config.class"
* <li>"java.util.logging.config.file"
* </ul>
* These two properties may be specified on the command line to the "java"
* command, or as system property definitions passed to JNI_CreateJavaVM.
* <p>
* If the "java.util.logging.config.class" property is set, then the
* property value is treated as a class name. The given class will be
* loaded, an object will be instantiated, and that object's constructor
* is responsible for reading in the initial configuration. (That object
* may use other system properties to control its configuration.) The
* alternate configuration class can use <tt>readConfiguration(InputStream)
* to define properties in the LogManager.
* <p>
* If "java.util.logging.config.class" property is <b>not set,
* then the "java.util.logging.config.file" system property can be used
* to specify a properties file (in java.util.Properties format). The
* initial logging configuration will be read from this file.
* <p>
* If neither of these properties is defined then the LogManager uses its
* default configuration. The default configuration is typically loaded from the
* properties file "{@code lib/logging.properties}" in the Java installation
* directory.
* <p>
* The properties for loggers and Handlers will have names starting
* with the dot-separated name for the handler or logger.
* <p>
* The global logging properties may include:
* <ul>
* <li>A property "handlers". This defines a whitespace or comma separated
* list of class names for handler classes to load and register as
* handlers on the root Logger (the Logger named ""). Each class
* name must be for a Handler class which has a default constructor.
* Note that these Handlers may be created lazily, when they are
* first used.
*
* <li>A property "<logger>.handlers". This defines a whitespace or
* comma separated list of class names for handlers classes to
* load and register as handlers to the specified logger. Each class
* name must be for a Handler class which has a default constructor.
* Note that these Handlers may be created lazily, when they are
* first used.
*
* <li>A property "<logger>.useParentHandlers". This defines a boolean
* value. By default every logger calls its parent in addition to
* handling the logging message itself, this often result in messages
* being handled by the root logger as well. When setting this property
* to false a Handler needs to be configured for this logger otherwise
* no logging messages are delivered.
*
* <li>A property "config". This property is intended to allow
* arbitrary configuration code to be run. The property defines a
* whitespace or comma separated list of class names. A new instance will be
* created for each named class. The default constructor of each class
* may execute arbitrary code to update the logging configuration, such as
* setting logger levels, adding handlers, adding filters, etc.
* </ul>
* <p>
* Note that all classes loaded during LogManager configuration are
* first searched on the system class path before any user class path.
* That includes the LogManager class, any config classes, and any
* handler classes.
* <p>
* Loggers are organized into a naming hierarchy based on their
* dot separated names. Thus "a.b.c" is a child of "a.b", but
* "a.b1" and a.b2" are peers.
* <p>
* All properties whose names end with ".level" are assumed to define
* log levels for Loggers. Thus "foo.level" defines a log level for
* the logger called "foo" and (recursively) for any of its children
* in the naming hierarchy. Log Levels are applied in the order they
* are defined in the properties file. Thus level settings for child
* nodes in the tree should come after settings for their parents.
* The property name ".level" can be used to set the level for the
* root of the tree.
* <p>
* All methods on the LogManager object are multi-thread safe.
*
* @since 1.4
*/
public class LogManager {
// The global LogManager object
private static final LogManager manager;
// 'props' is assigned within a lock but accessed without it.
// Declaring it volatile makes sure that another thread will not
// be able to see a partially constructed 'props' object.
// (seeing a partially constructed 'props' object can result in
// NPE being thrown in Hashtable.get(), because it leaves the door
// open for props.getProperties() to be called before the construcor
// of Hashtable is actually completed).
private volatile Properties props = new Properties();
private final static Level defaultLevel = Level.INFO;
// The map of the registered listeners. The map value is the registration
// count to allow for cases where the same listener is registered many times.
private final Map<Object,Integer> listenerMap = new HashMap<>();
// LoggerContext for system loggers and user loggers
private final LoggerContext systemContext = new SystemLoggerContext();
private final LoggerContext userContext = new LoggerContext();
// non final field - make it volatile to make sure that other threads
// will see the new value once ensureLogManagerInitialized() has finished
// executing.
private volatile Logger rootLogger;
// Have we done the primordial reading of the configuration file?
// (Must be done after a suitable amount of java.lang.System
// initialization has been done)
private volatile boolean readPrimordialConfiguration;
// Have we initialized global (root) handlers yet?
// This gets set to false in readConfiguration
private boolean initializedGlobalHandlers = true;
// True if JVM death is imminent and the exit hook has been called.
private boolean deathImminent;
static {
manager = AccessController.doPrivileged(new PrivilegedAction<LogManager>() {
@Override
public LogManager run() {
LogManager mgr = null;
String cname = null;
try {
cname = System.getProperty("java.util.logging.manager");
if (cname != null) {
try {
Class<?> clz = ClassLoader.getSystemClassLoader()
.loadClass(cname);
mgr = (LogManager) clz.newInstance();
} catch (ClassNotFoundException ex) {
Class<?> clz = Thread.currentThread()
.getContextClassLoader().loadClass(cname);
mgr = (LogManager) clz.newInstance();
}
}
} catch (Exception ex) {
System.err.println("Could not load Logmanager \"" + cname + "\"");
ex.printStackTrace();
}
if (mgr == null) {
mgr = new LogManager();
}
return mgr;
}
});
}
// This private class is used as a shutdown hook.
// It does a "reset" to close all open handlers.
private class Cleaner extends Thread {
private Cleaner() {
/* Set context class loader to null in order to avoid
* keeping a strong reference to an application classloader.
*/
this.setContextClassLoader(null);
}
@Override
public void run() {
// This is to ensure the LogManager.<clinit> is completed
// before synchronized block. Otherwise deadlocks are possible.
LogManager mgr = manager;
// If the global handlers haven't been initialized yet, we
// don't want to initialize them just so we can close them!
synchronized (LogManager.this) {
// Note that death is imminent.
deathImminent = true;
initializedGlobalHandlers = true;
}
// Do a reset to close all active handlers.
reset();
}
}
/**
* Protected constructor. This is protected so that container applications
* (such as J2EE containers) can subclass the object. It is non-public as
* it is intended that there only be one LogManager object, whose value is
* retrieved by calling LogManager.getLogManager.
*/
protected LogManager() {
this(checkSubclassPermissions());
}
private LogManager(Void checked) {
// Add a shutdown hook to close the global handlers.
try {
Runtime.getRuntime().addShutdownHook(new Cleaner());
} catch (IllegalStateException e) {
// If the VM is already shutting down,
// We do not need to register shutdownHook.
}
}
private static Void checkSubclassPermissions() {
final SecurityManager sm = System.getSecurityManager();
if (sm != null) {
// These permission will be checked in the LogManager constructor,
// in order to register the Cleaner() thread as a shutdown hook.
// Check them here to avoid the penalty of constructing the object
// etc...
sm.checkPermission(new RuntimePermission("shutdownHooks"));
sm.checkPermission(new RuntimePermission("setContextClassLoader"));
}
return null;
}
/**
* Lazy initialization: if this instance of manager is the global
* manager then this method will read the initial configuration and
* add the root logger and global logger by calling addLogger().
*
* Note that it is subtly different from what we do in LoggerContext.
* In LoggerContext we're patching up the logger context tree in order to add
* the root and global logger *to the context tree*.
*
* For this to work, addLogger() must have already have been called
* once on the LogManager instance for the default logger being
* added.
*
* This is why ensureLogManagerInitialized() needs to be called before
* any logger is added to any logger context.
*
*/
private boolean initializedCalled = false;
private volatile boolean initializationDone = false;
final void ensureLogManagerInitialized() {
final LogManager owner = this;
if (initializationDone || owner != manager) {
// we don't want to do this twice, and we don't want to do
// this on private manager instances.
return;
}
// Maybe another thread has called ensureLogManagerInitialized()
// before us and is still executing it. If so we will block until
// the log manager has finished initialized, then acquire the monitor,
// notice that initializationDone is now true and return.
// Otherwise - we have come here first! We will acquire the monitor,
// see that initializationDone is still false, and perform the
// initialization.
//
synchronized(this) {
// If initializedCalled is true it means that we're already in
// the process of initializing the LogManager in this thread.
// There has been a recursive call to ensureLogManagerInitialized().
final boolean isRecursiveInitialization = (initializedCalled == true);
assert initializedCalled || !initializationDone
: "Initialization can't be done if initialized has not been called!";
if (isRecursiveInitialization || initializationDone) {
// If isRecursiveInitialization is true it means that we're
// already in the process of initializing the LogManager in
// this thread. There has been a recursive call to
// ensureLogManagerInitialized(). We should not proceed as
// it would lead to infinite recursion.
//
// If initializationDone is true then it means the manager
// has finished initializing; just return: we're done.
return;
}
// Calling addLogger below will in turn call requiresDefaultLogger()
// which will call ensureLogManagerInitialized().
// We use initializedCalled to break the recursion.
initializedCalled = true;
try {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
assert rootLogger == null;
assert initializedCalled && !initializationDone;
// Read configuration.
owner.readPrimordialConfiguration();
// Create and retain Logger for the root of the namespace.
owner.rootLogger = owner.new RootLogger();
owner.addLogger(owner.rootLogger);
if (!owner.rootLogger.isLevelInitialized()) {
owner.rootLogger.setLevel(defaultLevel);
}
// Adding the global Logger.
// Do not call Logger.getGlobal() here as this might trigger
// subtle inter-dependency issues.
@SuppressWarnings("deprecation")
final Logger global = Logger.global;
// Make sure the global logger will be registered in the
// global manager
owner.addLogger(global);
return null;
}
});
} finally {
initializationDone = true;
}
}
}
/**
* Returns the global LogManager object.
* @return the global LogManager object
*/
public static LogManager getLogManager() {
if (manager != null) {
manager.ensureLogManagerInitialized();
}
return manager;
}
private void readPrimordialConfiguration() {
if (!readPrimordialConfiguration) {
synchronized (this) {
if (!readPrimordialConfiguration) {
// If System.in/out/err are null, it's a good
// indication that we're still in the
// bootstrapping phase
if (System.out == null) {
return;
}
readPrimordialConfiguration = true;
try {
AccessController.doPrivileged(new PrivilegedExceptionAction<Void>() {
@Override
public Void run() throws Exception {
readConfiguration();
// Platform loggers begin to delegate to java.util.logging.Logger
sun.util.logging.PlatformLogger.redirectPlatformLoggers();
return null;
}
});
} catch (Exception ex) {
assert false : "Exception raised while reading logging configuration: " + ex;
}
}
}
}
}
/**
* Adds an event listener to be invoked when the logging
* properties are re-read. Adding multiple instances of
* the same event Listener results in multiple entries
* in the property event listener table.
*
* <p>WARNING: This method is omitted from this class in all subset
* Profiles of Java SE that do not include the {@code java.beans} package.
* </p>
*
* @param l event listener
* @exception SecurityException if a security manager exists and if
* the caller does not have LoggingPermission("control").
* @exception NullPointerException if the PropertyChangeListener is null.
* @deprecated The dependency on {@code PropertyChangeListener} creates a
* significant impediment to future modularization of the Java
* platform. This method will be removed in a future release.
* The global {@code LogManager} can detect changes to the
* logging configuration by overridding the {@link
* #readConfiguration readConfiguration} method.
*/
@Deprecated
public void addPropertyChangeListener(PropertyChangeListener l) throws SecurityException {
PropertyChangeListener listener = Objects.requireNonNull(l);
checkPermission();
synchronized (listenerMap) {
// increment the registration count if already registered
Integer value = listenerMap.get(listener);
value = (value == null) ? 1 : (value + 1);
listenerMap.put(listener, value);
}
}
/**
* Removes an event listener for property change events.
* If the same listener instance has been added to the listener table
* through multiple invocations of <CODE>addPropertyChangeListener,
* then an equivalent number of
* <CODE>removePropertyChangeListener invocations are required to remove
* all instances of that listener from the listener table.
* <P>
* Returns silently if the given listener is not found.
*
* <p>WARNING: This method is omitted from this class in all subset
* Profiles of Java SE that do not include the {@code java.beans} package.
* </p>
*
* @param l event listener (can be null)
* @exception SecurityException if a security manager exists and if
* the caller does not have LoggingPermission("control").
* @deprecated The dependency on {@code PropertyChangeListener} creates a
* significant impediment to future modularization of the Java
* platform. This method will be removed in a future release.
* The global {@code LogManager} can detect changes to the
* logging configuration by overridding the {@link
* #readConfiguration readConfiguration} method.
*/
@Deprecated
public void removePropertyChangeListener(PropertyChangeListener l) throws SecurityException {
checkPermission();
if (l != null) {
PropertyChangeListener listener = l;
synchronized (listenerMap) {
Integer value = listenerMap.get(listener);
if (value != null) {
// remove from map if registration count is 1, otherwise
// just decrement its count
int i = value.intValue();
if (i == 1) {
listenerMap.remove(listener);
} else {
assert i > 1;
listenerMap.put(listener, i - 1);
}
}
}
}
}
// LoggerContext maps from AppContext
private WeakHashMap<Object, LoggerContext> contextsMap = null;
// Returns the LoggerContext for the user code (i.e. application or AppContext).
// Loggers are isolated from each AppContext.
private LoggerContext getUserContext() {
LoggerContext context = null;
SecurityManager sm = System.getSecurityManager();
JavaAWTAccess javaAwtAccess = SharedSecrets.getJavaAWTAccess();
if (sm != null && javaAwtAccess != null) {
// for each applet, it has its own LoggerContext isolated from others
synchronized (javaAwtAccess) {
// find the AppContext of the applet code
// will be null if we are in the main app context.
final Object ecx = javaAwtAccess.getAppletContext();
if (ecx != null) {
if (contextsMap == null) {
contextsMap = new WeakHashMap<>();
}
context = contextsMap.get(ecx);
if (context == null) {
// Create a new LoggerContext for the applet.
context = new LoggerContext();
contextsMap.put(ecx, context);
}
}
}
}
// for standalone app, return userContext
return context != null ? context : userContext;
}
// The system context.
final LoggerContext getSystemContext() {
return systemContext;
}
private List<LoggerContext> contexts() {
List<LoggerContext> cxs = new ArrayList<>();
cxs.add(getSystemContext());
cxs.add(getUserContext());
return cxs;
}
// Find or create a specified logger instance. If a logger has
// already been created with the given name it is returned.
// Otherwise a new logger instance is created and registered
// in the LogManager global namespace.
// This method will always return a non-null Logger object.
// Synchronization is not required here. All synchronization for
// adding a new Logger object is handled by addLogger().
//
// This method must delegate to the LogManager implementation to
// add a new Logger or return the one that has been added previously
// as a LogManager subclass may override the addLogger, getLogger,
// readConfiguration, and other methods.
Logger demandLogger(String name, String resourceBundleName, Class<?> caller) {
Logger result = getLogger(name);
if (result == null) {
// only allocate the new logger once
Logger newLogger = new Logger(name, resourceBundleName, caller, this);
do {
if (addLogger(newLogger)) {
// We successfully added the new Logger that we
// created above so return it without refetching.
return newLogger;
}
// We didn't add the new Logger that we created above
// because another thread added a Logger with the same
// name after our null check above and before our call
// to addLogger(). We have to refetch the Logger because
// addLogger() returns a boolean instead of the Logger
// reference itself. However, if the thread that created
// the other Logger is not holding a strong reference to
// the other Logger, then it is possible for the other
// Logger to be GC'ed after we saw it in addLogger() and
// before we can refetch it. If it has been GC'ed then
// we'll just loop around and try again.
result = getLogger(name);
} while (result == null);
}
return result;
}
Logger demandSystemLogger(String name, String resourceBundleName) {
// Add a system logger in the system context's namespace
final Logger sysLogger = getSystemContext().demandLogger(name, resourceBundleName);
// Add the system logger to the LogManager's namespace if not exist
// so that there is only one single logger of the given name.
// System loggers are visible to applications unless a logger of
// the same name has been added.
Logger logger;
do {
// First attempt to call addLogger instead of getLogger
// This would avoid potential bug in custom LogManager.getLogger
// implementation that adds a logger if does not exist
if (addLogger(sysLogger)) {
// successfully added the new system logger
logger = sysLogger;
} else {
logger = getLogger(name);
}
} while (logger == null);
// LogManager will set the sysLogger's handlers via LogManager.addLogger method.
if (logger != sysLogger && sysLogger.getHandlers().length == 0) {
// if logger already exists but handlers not set
final Logger l = logger;
AccessController.doPrivileged(new PrivilegedAction<Void>() {
@Override
public Void run() {
for (Handler hdl : l.getHandlers()) {
sysLogger.addHandler(hdl);
}
return null;
}
});
}
return sysLogger;
}
// LoggerContext maintains the logger namespace per context.
// The default LogManager implementation has one system context and user
// context. The system context is used to maintain the namespace for
// all system loggers and is queried by the system code. If a system logger
// doesn't exist in the user context, it'll also be added to the user context.
// The user context is queried by the user code and all other loggers are
// added in the user context.
class LoggerContext {
// Table of named Loggers that maps names to Loggers.
private final Hashtable<String,LoggerWeakRef> namedLoggers = new Hashtable<>();
// Tree of named Loggers
private final LogNode root;
private LoggerContext() {
this.root = new LogNode(null, this);
}
// Tells whether default loggers are required in this context.
// If true, the default loggers will be lazily added.
final boolean requiresDefaultLoggers() {
final boolean requiresDefaultLoggers = (getOwner() == manager);
if (requiresDefaultLoggers) {
getOwner().ensureLogManagerInitialized();
}
return requiresDefaultLoggers;
}
// This context's LogManager.
final LogManager getOwner() {
return LogManager.this;
}
// This context owner's root logger, which if not null, and if
// the context requires default loggers, will be added to the context
// logger's tree.
final Logger getRootLogger() {
return getOwner().rootLogger;
}
// The global logger, which if not null, and if
// the context requires default loggers, will be added to the context
// logger's tree.
final Logger getGlobalLogger() {
@SuppressWarnings("deprecated") // avoids initialization cycles.
final Logger global = Logger.global;
return global;
}
Logger demandLogger(String name, String resourceBundleName) {
// a LogManager subclass may have its own implementation to add and
// get a Logger. So delegate to the LogManager to do the work.
final LogManager owner = getOwner();
return owner.demandLogger(name, resourceBundleName, null);
}
// Due to subtle deadlock issues getUserContext() no longer
// calls addLocalLogger(rootLogger);
// Therefore - we need to add the default loggers later on.
// Checks that the context is properly initialized
// This is necessary before calling e.g. find(name)
// or getLoggerNames()
//
private void ensureInitialized() {
if (requiresDefaultLoggers()) {
// Ensure that the root and global loggers are set.
ensureDefaultLogger(getRootLogger());
ensureDefaultLogger(getGlobalLogger());
}
}
synchronized Logger findLogger(String name) {
// ensure that this context is properly initialized before
// looking for loggers.
ensureInitialized();
LoggerWeakRef ref = namedLoggers.get(name);
if (ref == null) {
return null;
}
Logger logger = ref.get();
if (logger == null) {
// Hashtable holds stale weak reference
// to a logger which has been GC-ed.
ref.dispose();
}
return logger;
}
// This method is called before adding a logger to the
// context.
// 'logger' is the context that will be added.
// This method will ensure that the defaults loggers are added
// before adding 'logger'.
//
private void ensureAllDefaultLoggers(Logger logger) {
if (requiresDefaultLoggers()) {
final String name = logger.getName();
if (!name.isEmpty()) {
ensureDefaultLogger(getRootLogger());
if (!Logger.GLOBAL_LOGGER_NAME.equals(name)) {
ensureDefaultLogger(getGlobalLogger());
}
}
}
}
private void ensureDefaultLogger(Logger logger) {
// Used for lazy addition of root logger and global logger
// to a LoggerContext.
// This check is simple sanity: we do not want that this
// method be called for anything else than Logger.global
// or owner.rootLogger.
if (!requiresDefaultLoggers() || logger == null
|| logger != Logger.global && logger != LogManager.this.rootLogger) {
// the case where we have a non null logger which is neither
// Logger.global nor manager.rootLogger indicates a serious
// issue - as ensureDefaultLogger should never be called
// with any other loggers than one of these two (or null - if
// e.g manager.rootLogger is not yet initialized)...
assert logger == null;
return;
}
// Adds the logger if it's not already there.
if (!namedLoggers.containsKey(logger.getName())) {
// It is important to prevent addLocalLogger to
// call ensureAllDefaultLoggers when we're in the process
// off adding one of those default loggers - as this would
// immediately cause a stack overflow.
// Therefore we must pass addDefaultLoggersIfNeeded=false,
// even if requiresDefaultLoggers is true.
addLocalLogger(logger, false);
}
}
boolean addLocalLogger(Logger logger) {
// no need to add default loggers if it's not required
return addLocalLogger(logger, requiresDefaultLoggers());
}
// Add a logger to this context. This method will only set its level
// and process parent loggers. It doesn't set its handlers.
synchronized boolean addLocalLogger(Logger logger, boolean addDefaultLoggersIfNeeded) {
// addDefaultLoggersIfNeeded serves to break recursion when adding
// default loggers. If we're adding one of the default loggers
// (we're being called from ensureDefaultLogger()) then
// addDefaultLoggersIfNeeded will be false: we don't want to
// call ensureAllDefaultLoggers again.
//
// Note: addDefaultLoggersIfNeeded can also be false when
// requiresDefaultLoggers is false - since calling
// ensureAllDefaultLoggers would have no effect in this case.
if (addDefaultLoggersIfNeeded) {
ensureAllDefaultLoggers(logger);
}
final String name = logger.getName();
if (name == null) {
throw new NullPointerException();
}
LoggerWeakRef ref = namedLoggers.get(name);
if (ref != null) {
if (ref.get() == null) {
// It's possible that the Logger was GC'ed after a
// drainLoggerRefQueueBounded() call above so allow
// a new one to be registered.
ref.dispose();
} else {
// We already have a registered logger with the given name.
return false;
}
}
// We're adding a new logger.
// Note that we are creating a weak reference here.
final LogManager owner = getOwner();
logger.setLogManager(owner);
ref = owner.new LoggerWeakRef(logger);
namedLoggers.put(name, ref);
// Apply any initial level defined for the new logger, unless
// the logger's level is already initialized
Level level = owner.getLevelProperty(name + ".level", null);
if (level != null && !logger.isLevelInitialized()) {
doSetLevel(logger, level);
}
// instantiation of the handler is done in the LogManager.addLogger
// implementation as a handler class may be only visible to LogManager
// subclass for the custom log manager case
processParentHandlers(logger, name);
// Find the new node and its parent.
LogNode node = getNode(name);
node.loggerRef = ref;
Logger parent = null;
LogNode nodep = node.parent;
while (nodep != null) {
LoggerWeakRef nodeRef = nodep.loggerRef;
if (nodeRef != null) {
parent = nodeRef.get();
if (parent != null) {
break;
}
}
nodep = nodep.parent;
}
if (parent != null) {
doSetParent(logger, parent);
}
// Walk over the children and tell them we are their new parent.
node.walkAndSetParent(logger);
// new LogNode is ready so tell the LoggerWeakRef about it
ref.setNode(node);
return true;
}
synchronized void removeLoggerRef(String name, LoggerWeakRef ref) {
namedLoggers.remove(name, ref);
}
synchronized Enumeration<String> getLoggerNames() {
// ensure that this context is properly initialized before
// returning logger names.
ensureInitialized();
return namedLoggers.keys();
}
// If logger.getUseParentHandlers() returns 'true' and any of the logger's
// parents have levels or handlers defined, make sure they are instantiated.
private void processParentHandlers(final Logger logger, final String name) {
final LogManager owner = getOwner();
AccessController.doPrivileged(new PrivilegedAction<Void>() {
@Override
public Void run() {
if (logger != owner.rootLogger) {
boolean useParent = owner.getBooleanProperty(name + ".useParentHandlers", true);
if (!useParent) {
logger.setUseParentHandlers(false);
}
}
return null;
}
});
int ix = 1;
for (;;) {
int ix2 = name.indexOf(".", ix);
if (ix2 < 0) {
break;
}
String pname = name.substring(0, ix2);
if (owner.getProperty(pname + ".level") != null ||
owner.getProperty(pname + ".handlers") != null) {
// This pname has a level/handlers definition.
// Make sure it exists.
demandLogger(pname, null);
}
ix = ix2+1;
}
}
// Gets a node in our tree of logger nodes.
// If necessary, create it.
LogNode getNode(String name) {
if (name == null || name.equals("")) {
return root;
}
LogNode node = root;
while (name.length() > 0) {
int ix = name.indexOf(".");
String head;
if (ix > 0) {
head = name.substring(0, ix);
name = name.substring(ix + 1);
} else {
head = name;
name = "";
}
if (node.children == null) {
node.children = new HashMap<>();
}
LogNode child = node.children.get(head);
if (child == null) {
child = new LogNode(node, this);
node.children.put(head, child);
}
node = child;
}
return node;
}
}
final class SystemLoggerContext extends LoggerContext {
// Add a system logger in the system context's namespace as well as
// in the LogManager's namespace if not exist so that there is only
// one single logger of the given name. System loggers are visible
// to applications unless a logger of the same name has been added.
@Override
Logger demandLogger(String name, String resourceBundleName) {
Logger result = findLogger(name);
if (result == null) {
// only allocate the new system logger once
Logger newLogger = new Logger(name, resourceBundleName, null, getOwner());
do {
if (addLocalLogger(newLogger)) {
// We successfully added the new Logger that we
// created above so return it without refetching.
result = newLogger;
} else {
// We didn't add the new Logger that we created above
// because another thread added a Logger with the same
// name after our null check above and before our call
// to addLogger(). We have to refetch the Logger because
// addLogger() returns a boolean instead of the Logger
// reference itself. However, if the thread that created
// the other Logger is not holding a strong reference to
// the other Logger, then it is possible for the other
// Logger to be GC'ed after we saw it in addLogger() and
// before we can refetch it. If it has been GC'ed then
// we'll just loop around and try again.
result = findLogger(name);
}
} while (result == null);
}
return result;
}
}
// Add new per logger handlers.
// We need to raise privilege here. All our decisions will
// be made based on the logging configuration, which can
// only be modified by trusted code.
private void loadLoggerHandlers(final Logger logger, final String name,
final String handlersPropertyName)
{
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
String names[] = parseClassNames(handlersPropertyName);
for (int i = 0; i < names.length; i++) {
String word = names[i];
try {
Class<?> clz = ClassLoader.getSystemClassLoader().loadClass(word);
Handler hdl = (Handler) clz.newInstance();
// Check if there is a property defining the
// this handler's level.
String levs = getProperty(word + ".level");
if (levs != null) {
Level l = Level.findLevel(levs);
if (l != null) {
hdl.setLevel(l);
} else {
// Probably a bad level. Drop through.
System.err.println("Can't set level for " + word);
}
}
// Add this Handler to the logger
logger.addHandler(hdl);
} catch (Exception ex) {
System.err.println("Can't load log handler \"" + word + "\"");
System.err.println("" + ex);
ex.printStackTrace();
}
}
return null;
}
});
}
// loggerRefQueue holds LoggerWeakRef objects for Logger objects
// that have been GC'ed.
private final ReferenceQueue<Logger> loggerRefQueue
= new ReferenceQueue<>();
// Package-level inner class.
// Helper class for managing WeakReferences to Logger objects.
//
// LogManager.namedLoggers
// - has weak references to all named Loggers
// - namedLoggers keeps the LoggerWeakRef objects for the named
// Loggers around until we can deal with the book keeping for
// the named Logger that is being GC'ed.
// LogManager.LogNode.loggerRef
// - has a weak reference to a named Logger
// - the LogNode will also keep the LoggerWeakRef objects for
// the named Loggers around; currently LogNodes never go away.
// Logger.kids
// - has a weak reference to each direct child Logger; this
// includes anonymous and named Loggers
// - anonymous Loggers are always children of the rootLogger
// which is a strong reference; rootLogger.kids keeps the
// LoggerWeakRef objects for the anonymous Loggers around
// until we can deal with the book keeping.
//
final class LoggerWeakRef extends WeakReference<Logger> {
private String name; // for namedLoggers cleanup
private LogNode node; // for loggerRef cleanup
private WeakReference<Logger> parentRef; // for kids cleanup
private boolean disposed = false; // avoid calling dispose twice
LoggerWeakRef(Logger logger) {
super(logger, loggerRefQueue);
name = logger.getName(); // save for namedLoggers cleanup
}
// dispose of this LoggerWeakRef object
void dispose() {
// Avoid calling dispose twice. When a Logger is gc'ed, its
// LoggerWeakRef will be enqueued.
// However, a new logger of the same name may be added (or looked
// up) before the queue is drained. When that happens, dispose()
// will be called by addLocalLogger() or findLogger().
// Later when the queue is drained, dispose() will be called again
// for the same LoggerWeakRef. Marking LoggerWeakRef as disposed
// avoids processing the data twice (even though the code should
// now be reentrant).
synchronized(this) {
// Note to maintainers:
// Be careful not to call any method that tries to acquire
// another lock from within this block - as this would surely
// lead to deadlocks, given that dispose() can be called by
// multiple threads, and from within different synchronized
// methods/blocks.
if (disposed) return;
disposed = true;
}
final LogNode n = node;
if (n != null) {
// n.loggerRef can only be safely modified from within
// a lock on LoggerContext. removeLoggerRef is already
// synchronized on LoggerContext so calling
// n.context.removeLoggerRef from within this lock is safe.
synchronized (n.context) {
// if we have a LogNode, then we were a named Logger
// so clear namedLoggers weak ref to us
n.context.removeLoggerRef(name, this);
name = null; // clear our ref to the Logger's name
// LogNode may have been reused - so only clear
// LogNode.loggerRef if LogNode.loggerRef == this
if (n.loggerRef == this) {
n.loggerRef = null; // clear LogNode's weak ref to us
}
node = null; // clear our ref to LogNode
}
}
if (parentRef != null) {
// this LoggerWeakRef has or had a parent Logger
Logger parent = parentRef.get();
if (parent != null) {
// the parent Logger is still there so clear the
// parent Logger's weak ref to us
parent.removeChildLogger(this);
}
parentRef = null; // clear our weak ref to the parent Logger
}
}
// set the node field to the specified value
void setNode(LogNode node) {
this.node = node;
}
// set the parentRef field to the specified value
void setParentRef(WeakReference<Logger> parentRef) {
this.parentRef = parentRef;
}
}
// Package-level method.
// Drain some Logger objects that have been GC'ed.
//
// drainLoggerRefQueueBounded() is called by addLogger() below
// and by Logger.getAnonymousLogger(String) so we'll drain up to
// MAX_ITERATIONS GC'ed Loggers for every Logger we add.
//
// On a WinXP VMware client, a MAX_ITERATIONS value of 400 gives
// us about a 50/50 mix in increased weak ref counts versus
// decreased weak ref counts in the AnonLoggerWeakRefLeak test.
// Here are stats for cleaning up sets of 400 anonymous Loggers:
// - test duration 1 minute
// - sample size of 125 sets of 400
// - average: 1.99 ms
// - minimum: 0.57 ms
// - maximum: 25.3 ms
//
// The same config gives us a better decreased weak ref count
// than increased weak ref count in the LoggerWeakRefLeak test.
// Here are stats for cleaning up sets of 400 named Loggers:
// - test duration 2 minutes
// - sample size of 506 sets of 400
// - average: 0.57 ms
// - minimum: 0.02 ms
// - maximum: 10.9 ms
//
private final static int MAX_ITERATIONS = 400;
final void drainLoggerRefQueueBounded() {
for (int i = 0; i < MAX_ITERATIONS; i++) {
if (loggerRefQueue == null) {
// haven't finished loading LogManager yet
break;
}
LoggerWeakRef ref = (LoggerWeakRef) loggerRefQueue.poll();
if (ref == null) {
break;
}
// a Logger object has been GC'ed so clean it up
ref.dispose();
}
}
/**
* Add a named logger. This does nothing and returns false if a logger
* with the same name is already registered.
* <p>
* The Logger factory methods call this method to register each
* newly created Logger.
* <p>
* The application should retain its own reference to the Logger
* object to avoid it being garbage collected. The LogManager
* may only retain a weak reference.
*
* @param logger the new logger.
* @return true if the argument logger was registered successfully,
* false if a logger of that name already exists.
* @exception NullPointerException if the logger name is null.
*/
public boolean addLogger(Logger logger) {
final String name = logger.getName();
if (name == null) {
throw new NullPointerException();
}
drainLoggerRefQueueBounded();
LoggerContext cx = getUserContext();
if (cx.addLocalLogger(logger)) {
// Do we have a per logger handler too?
// Note: this will add a 200ms penalty
loadLoggerHandlers(logger, name, name + ".handlers");
return true;
} else {
return false;
}
}
// Private method to set a level on a logger.
// If necessary, we raise privilege before doing the call.
private static void doSetLevel(final Logger logger, final Level level) {
SecurityManager sm = System.getSecurityManager();
if (sm == null) {
// There is no security manager, so things are easy.
logger.setLevel(level);
return;
}
// There is a security manager. Raise privilege before
// calling setLevel.
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
logger.setLevel(level);
return null;
}});
}
// Private method to set a parent on a logger.
// If necessary, we raise privilege before doing the setParent call.
private static void doSetParent(final Logger logger, final Logger parent) {
SecurityManager sm = System.getSecurityManager();
if (sm == null) {
// There is no security manager, so things are easy.
logger.setParent(parent);
return;
}
// There is a security manager. Raise privilege before
// calling setParent.
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
logger.setParent(parent);
return null;
}});
}
/**
* Method to find a named logger.
* <p>
* Note that since untrusted code may create loggers with
* arbitrary names this method should not be relied on to
* find Loggers for security sensitive logging.
* It is also important to note that the Logger associated with the
* String {@code name} may be garbage collected at any time if there
* is no strong reference to the Logger. The caller of this method
* must check the return value for null in order to properly handle
* the case where the Logger has been garbage collected.
* <p>
* @param name name of the logger
* @return matching logger or null if none is found
*/
public Logger getLogger(String name) {
return getUserContext().findLogger(name);
}
/**
* Get an enumeration of known logger names.
* <p>
* Note: Loggers may be added dynamically as new classes are loaded.
* This method only reports on the loggers that are currently registered.
* It is also important to note that this method only returns the name
* of a Logger, not a strong reference to the Logger itself.
* The returned String does nothing to prevent the Logger from being
* garbage collected. In particular, if the returned name is passed
* to {@code LogManager.getLogger()}, then the caller must check the
* return value from {@code LogManager.getLogger()} for null to properly
* handle the case where the Logger has been garbage collected in the
* time since its name was returned by this method.
* <p>
* @return enumeration of logger name strings
*/
public Enumeration<String> getLoggerNames() {
return getUserContext().getLoggerNames();
}
/**
* Reinitialize the logging properties and reread the logging configuration.
* <p>
* The same rules are used for locating the configuration properties
* as are used at startup. So normally the logging properties will
* be re-read from the same file that was used at startup.
* <P>
* Any log level definitions in the new configuration file will be
* applied using Logger.setLevel(), if the target Logger exists.
* <p>
* A PropertyChangeEvent will be fired after the properties are read.
*
* @exception SecurityException if a security manager exists and if
* the caller does not have LoggingPermission("control").
* @exception IOException if there are IO problems reading the configuration.
*/
public void readConfiguration() throws IOException, SecurityException {
checkPermission();
// if a configuration class is specified, load it and use it.
String cname = System.getProperty("java.util.logging.config.class");
if (cname != null) {
try {
// Instantiate the named class. It is its constructor's
// responsibility to initialize the logging configuration, by
// calling readConfiguration(InputStream) with a suitable stream.
try {
Class<?> clz = ClassLoader.getSystemClassLoader().loadClass(cname);
clz.newInstance();
return;
} catch (ClassNotFoundException ex) {
Class<?> clz = Thread.currentThread().getContextClassLoader().loadClass(cname);
clz.newInstance();
return;
}
} catch (Exception ex) {
System.err.println("Logging configuration class \"" + cname + "\" failed");
System.err.println("" + ex);
// keep going and useful config file.
}
}
String fname = System.getProperty("java.util.logging.config.file");
if (fname == null) {
fname = System.getProperty("java.home");
if (fname == null) {
throw new Error("Can't find java.home ??");
}
File f = new File(fname, "lib");
f = new File(f, "logging.properties");
fname = f.getCanonicalPath();
}
try (final InputStream in = new FileInputStream(fname)) {
final BufferedInputStream bin = new BufferedInputStream(in);
readConfiguration(bin);
}
}
/**
* Reset the logging configuration.
* <p>
* For all named loggers, the reset operation removes and closes
* all Handlers and (except for the root logger) sets the level
* to null. The root logger's level is set to Level.INFO.
*
* @exception SecurityException if a security manager exists and if
* the caller does not have LoggingPermission("control").
*/
public void reset() throws SecurityException {
checkPermission();
synchronized (this) {
props = new Properties();
// Since we are doing a reset we no longer want to initialize
// the global handlers, if they haven't been initialized yet.
initializedGlobalHandlers = true;
}
for (LoggerContext cx : contexts()) {
Enumeration<String> enum_ = cx.getLoggerNames();
while (enum_.hasMoreElements()) {
String name = enum_.nextElement();
Logger logger = cx.findLogger(name);
if (logger != null) {
resetLogger(logger);
}
}
}
}
// Private method to reset an individual target logger.
private void resetLogger(Logger logger) {
// Close all the Logger's handlers.
Handler[] targets = logger.getHandlers();
for (int i = 0; i < targets.length; i++) {
Handler h = targets[i];
logger.removeHandler(h);
try {
h.close();
} catch (Exception ex) {
// Problems closing a handler? Keep going...
}
}
String name = logger.getName();
if (name != null && name.equals("")) {
// This is the root logger.
logger.setLevel(defaultLevel);
} else {
logger.setLevel(null);
}
}
// get a list of whitespace separated classnames from a property.
private String[] parseClassNames(String propertyName) {
String hands = getProperty(propertyName);
if (hands == null) {
return new String[0];
}
hands = hands.trim();
int ix = 0;
final List<String> result = new ArrayList<>();
while (ix < hands.length()) {
int end = ix;
while (end < hands.length()) {
if (Character.isWhitespace(hands.charAt(end))) {
break;
}
if (hands.charAt(end) == ',') {
break;
}
end++;
}
String word = hands.substring(ix, end);
ix = end+1;
word = word.trim();
if (word.length() == 0) {
continue;
}
result.add(word);
}
return result.toArray(new String[result.size()]);
}
/**
* Reinitialize the logging properties and reread the logging configuration
* from the given stream, which should be in java.util.Properties format.
* A PropertyChangeEvent will be fired after the properties are read.
* <p>
* Any log level definitions in the new configuration file will be
* applied using Logger.setLevel(), if the target Logger exists.
*
* @param ins stream to read properties from
* @exception SecurityException if a security manager exists and if
* the caller does not have LoggingPermission("control").
* @exception IOException if there are problems reading from the stream.
*/
public void readConfiguration(InputStream ins) throws IOException, SecurityException {
checkPermission();
reset();
// Load the properties
props.load(ins);
// Instantiate new configuration objects.
String names[] = parseClassNames("config");
for (int i = 0; i < names.length; i++) {
String word = names[i];
try {
Class<?> clz = ClassLoader.getSystemClassLoader().loadClass(word);
clz.newInstance();
} catch (Exception ex) {
System.err.println("Can't load config class \"" + word + "\"");
System.err.println("" + ex);
// ex.printStackTrace();
}
}
// Set levels on any pre-existing loggers, based on the new properties.
setLevelsOnExistingLoggers();
// Notify any interested parties that our properties have changed.
// We first take a copy of the listener map so that we aren't holding any
// locks when calling the listeners.
Map<Object,Integer> listeners = null;
synchronized (listenerMap) {
if (!listenerMap.isEmpty())
listeners = new HashMap<>(listenerMap);
}
if (listeners != null) {
assert Beans.isBeansPresent();
Object ev = Beans.newPropertyChangeEvent(LogManager.class, null, null, null);
for (Map.Entry<Object,Integer> entry : listeners.entrySet()) {
Object listener = entry.getKey();
int count = entry.getValue().intValue();
for (int i = 0; i < count; i++) {
Beans.invokePropertyChange(listener, ev);
}
}
}
// Note that we need to reinitialize global handles when
// they are first referenced.
synchronized (this) {
initializedGlobalHandlers = false;
}
}
/**
* Get the value of a logging property.
* The method returns null if the property is not found.
* @param name property name
* @return property value
*/
public String getProperty(String name) {
return props.getProperty(name);
}
// Package private method to get a String property.
// If the property is not defined we return the given
// default value.
String getStringProperty(String name, String defaultValue) {
String val = getProperty(name);
if (val == null) {
return defaultValue;
}
return val.trim();
}
// Package private method to get an integer property.
// If the property is not defined or cannot be parsed
// we return the given default value.
int getIntProperty(String name, int defaultValue) {
String val = getProperty(name);
if (val == null) {
return defaultValue;
}
try {
return Integer.parseInt(val.trim());
} catch (Exception ex) {
return defaultValue;
}
}
// Package private method to get a boolean property.
// If the property is not defined or cannot be parsed
// we return the given default value.
boolean getBooleanProperty(String name, boolean defaultValue) {
String val = getProperty(name);
if (val == null) {
return defaultValue;
}
val = val.toLowerCase();
if (val.equals("true") || val.equals("1")) {
return true;
} else if (val.equals("false") || val.equals("0")) {
return false;
}
return defaultValue;
}
// Package private method to get a Level property.
// If the property is not defined or cannot be parsed
// we return the given default value.
Level getLevelProperty(String name, Level defaultValue) {
String val = getProperty(name);
if (val == null) {
return defaultValue;
}
Level l = Level.findLevel(val.trim());
return l != null ? l : defaultValue;
}
// Package private method to get a filter property.
// We return an instance of the class named by the "name"
// property. If the property is not defined or has problems
// we return the defaultValue.
Filter getFilterProperty(String name, Filter defaultValue) {
String val = getProperty(name);
try {
if (val != null) {
Class<?> clz = ClassLoader.getSystemClassLoader().loadClass(val);
return (Filter) clz.newInstance();
}
} catch (Exception ex) {
// We got one of a variety of exceptions in creating the
// class or creating an instance.
// Drop through.
}
// We got an exception. Return the defaultValue.
return defaultValue;
}
// Package private method to get a formatter property.
// We return an instance of the class named by the "name"
// property. If the property is not defined or has problems
// we return the defaultValue.
Formatter getFormatterProperty(String name, Formatter defaultValue) {
String val = getProperty(name);
try {
if (val != null) {
Class<?> clz = ClassLoader.getSystemClassLoader().loadClass(val);
return (Formatter) clz.newInstance();
}
} catch (Exception ex) {
// We got one of a variety of exceptions in creating the
// class or creating an instance.
// Drop through.
}
// We got an exception. Return the defaultValue.
return defaultValue;
}
// Private method to load the global handlers.
// We do the real work lazily, when the global handlers
// are first used.
private synchronized void initializeGlobalHandlers() {
if (initializedGlobalHandlers) {
return;
}
initializedGlobalHandlers = true;
if (deathImminent) {
// Aaargh...
// The VM is shutting down and our exit hook has been called.
// Avoid allocating global handlers.
return;
}
loadLoggerHandlers(rootLogger, null, "handlers");
}
private final Permission controlPermission = new LoggingPermission("control", null);
void checkPermission() {
SecurityManager sm = System.getSecurityManager();
if (sm != null)
sm.checkPermission(controlPermission);
}
/**
* Check that the current context is trusted to modify the logging
* configuration. This requires LoggingPermission("control").
* <p>
* If the check fails we throw a SecurityException, otherwise
* we return normally.
*
* @exception SecurityException if a security manager exists and if
* the caller does not have LoggingPermission("control").
*/
public void checkAccess() throws SecurityException {
checkPermission();
}
// Nested class to represent a node in our tree of named loggers.
private static class LogNode {
HashMap<String,LogNode> children;
LoggerWeakRef loggerRef;
LogNode parent;
final LoggerContext context;
LogNode(LogNode parent, LoggerContext context) {
this.parent = parent;
this.context = context;
}
// Recursive method to walk the tree below a node and set
// a new parent logger.
void walkAndSetParent(Logger parent) {
if (children == null) {
return;
}
Iterator<LogNode> values = children.values().iterator();
while (values.hasNext()) {
LogNode node = values.next();
LoggerWeakRef ref = node.loggerRef;
Logger logger = (ref == null) ? null : ref.get();
if (logger == null) {
node.walkAndSetParent(parent);
} else {
doSetParent(logger, parent);
}
}
}
}
// We use a subclass of Logger for the root logger, so
// that we only instantiate the global handlers when they
// are first needed.
private final class RootLogger extends Logger {
private RootLogger() {
// We do not call the protected Logger two args constructor here,
// to avoid calling LogManager.getLogManager() from within the
// RootLogger constructor.
super("", null, null, LogManager.this);
}
@Override
public void log(LogRecord record) {
// Make sure that the global handlers have been instantiated.
initializeGlobalHandlers();
super.log(record);
}
@Override
public void addHandler(Handler h) {
initializeGlobalHandlers();
super.addHandler(h);
}
@Override
public void removeHandler(Handler h) {
initializeGlobalHandlers();
super.removeHandler(h);
}
@Override
public Handler[] getHandlers() {
initializeGlobalHandlers();
return super.getHandlers();
}
}
// Private method to be called when the configuration has
// changed to apply any level settings to any pre-existing loggers.
synchronized private void setLevelsOnExistingLoggers() {
Enumeration<?> enum_ = props.propertyNames();
while (enum_.hasMoreElements()) {
String key = (String)enum_.nextElement();
if (!key.endsWith(".level")) {
// Not a level definition.
continue;
}
int ix = key.length() - 6;
String name = key.substring(0, ix);
Level level = getLevelProperty(key, null);
if (level == null) {
System.err.println("Bad level value for property: " + key);
continue;
}
for (LoggerContext cx : contexts()) {
Logger l = cx.findLogger(name);
if (l == null) {
continue;
}
l.setLevel(level);
}
}
}
// Management Support
private static LoggingMXBean loggingMXBean = null;
/**
* String representation of the
* {@link javax.management.ObjectName} for the management interface
* for the logging facility.
*
* @see java.lang.management.PlatformLoggingMXBean
* @see java.util.logging.LoggingMXBean
*
* @since 1.5
*/
public final static String LOGGING_MXBEAN_NAME
= "java.util.logging:type=Logging";
/**
* Returns <tt>LoggingMXBean for managing loggers.
* An alternative way to manage loggers is through the
* {@link java.lang.management.PlatformLoggingMXBean} interface
* that can be obtained by calling:
* <pre>
* PlatformLoggingMXBean logging = {@link java.lang.management.ManagementFactory#getPlatformMXBean(Class)
* ManagementFactory.getPlatformMXBean}(PlatformLoggingMXBean.class);
* </pre>
*
* @return a {@link LoggingMXBean} object.
*
* @see java.lang.management.PlatformLoggingMXBean
* @since 1.5
*/
public static synchronized LoggingMXBean getLoggingMXBean() {
if (loggingMXBean == null) {
loggingMXBean = new Logging();
}
return loggingMXBean;
}
/**
* A class that provides access to the java.beans.PropertyChangeListener
* and java.beans.PropertyChangeEvent without creating a static dependency
* on java.beans. This class can be removed once the addPropertyChangeListener
* and removePropertyChangeListener methods are removed.
*/
private static class Beans {
private static final Class<?> propertyChangeListenerClass =
getClass("java.beans.PropertyChangeListener");
private static final Class<?> propertyChangeEventClass =
getClass("java.beans.PropertyChangeEvent");
private static final Method propertyChangeMethod =
getMethod(propertyChangeListenerClass,
"propertyChange",
propertyChangeEventClass);
private static final Constructor<?> propertyEventCtor =
getConstructor(propertyChangeEventClass,
Object.class,
String.class,
Object.class,
Object.class);
private static Class<?> getClass(String name) {
try {
return Class.forName(name, true, Beans.class.getClassLoader());
} catch (ClassNotFoundException e) {
return null;
}
}
private static Constructor<?> getConstructor(Class c, Class... types) {
try {
return (c == null) ? null : c.getDeclaredConstructor(types);
} catch (NoSuchMethodException x) {
throw new AssertionError(x);
}
}
private static Method getMethod(Class<?> c, String name, Class... types) {
try {
return (c == null) ? null : c.getMethod(name, types);
} catch (NoSuchMethodException e) {
throw new AssertionError(e);
}
}
/**
* Returns {@code true} if java.beans is present.
*/
static boolean isBeansPresent() {
return propertyChangeListenerClass != null &&
propertyChangeEventClass != null;
}
/**
* Returns a new PropertyChangeEvent with the given source, property
* name, old and new values.
*/
static Object newPropertyChangeEvent(Object source, String prop,
Object oldValue, Object newValue)
{
try {
return propertyEventCtor.newInstance(source, prop, oldValue, newValue);
} catch (InstantiationException | IllegalAccessException x) {
throw new AssertionError(x);
} catch (InvocationTargetException x) {
Throwable cause = x.getCause();
if (cause instanceof Error)
throw (Error)cause;
if (cause instanceof RuntimeException)
throw (RuntimeException)cause;
throw new AssertionError(x);
}
}
/**
* Invokes the given PropertyChangeListener's propertyChange method
* with the given event.
*/
static void invokePropertyChange(Object listener, Object ev) {
try {
propertyChangeMethod.invoke(listener, ev);
} catch (IllegalAccessException x) {
throw new AssertionError(x);
} catch (InvocationTargetException x) {
Throwable cause = x.getCause();
if (cause instanceof Error)
throw (Error)cause;
if (cause instanceof RuntimeException)
throw (RuntimeException)cause;
throw new AssertionError(x);
}
}
}
}
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