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package jdk.internal.logger;
import jdk.internal.misc.VM;
import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.util.HashMap;
import java.util.Map;
import java.util.function.Function;
import java.util.Objects;
import java.lang.System.LoggerFinder;
import java.lang.System.Logger;
import java.lang.ref.ReferenceQueue;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Collection;
import java.util.ResourceBundle;
Internal Service Provider Interface (SPI) that makes it possible to use java.util.logging
as backend when the
sun.util.logging.internal.LoggingProviderImpl
is present. The JDK default implementation of the LoggerFinder
will attempt to locate and load an installed implementation of the DefaultLoggerFinder
. If java.util.logging
is present, this will usually resolve to an instance of sun.util.logging.internal.LoggingProviderImpl
. Otherwise, if no concrete service provider is declared for DefaultLoggerFinder
, the default implementation provided by this class will be used.
When the
sun.util.logging.internal.LoggingProviderImpl
is not present then the default implementation provided by this class is to use a simple logger that will log messages whose level is INFO and above to the console. These simple loggers are not configurable.
When configuration is needed, an application should either link with java.util.logging
- and use the java.util.logging
for configuration, or link with another implementation
of the LoggerFinder
that provides the necessary configuration.
See Also: - LoggerFinder
- logger
- internal
API Note: Programmers are not expected to call this class directly. Instead they should rely on the static methods defined by java.lang.System
or
sun.util.logging.PlatformLogger
.
/**
* Internal Service Provider Interface (SPI) that makes it possible to use
* {@code java.util.logging} as backend when the {@link
* sun.util.logging.internal.LoggingProviderImpl
* sun.util.logging.internal.LoggingProviderImpl} is present.
* <p>
* The JDK default implementation of the {@link LoggerFinder} will
* attempt to locate and load an {@linkplain
* java.util.ServiceLoader#loadInstalled(java.lang.Class) installed}
* implementation of the {@code DefaultLoggerFinder}. If {@code java.util.logging}
* is present, this will usually resolve to an instance of {@link
* sun.util.logging.internal.LoggingProviderImpl sun.util.logging.internal.LoggingProviderImpl}.
* Otherwise, if no concrete service provider is declared for
* {@code DefaultLoggerFinder}, the default implementation provided by this class
* will be used.
* <p>
* When the {@link sun.util.logging.internal.LoggingProviderImpl
* sun.util.logging.internal.LoggingProviderImpl} is not present then the
* default implementation provided by this class is to use a simple logger
* that will log messages whose level is INFO and above to the console.
* These simple loggers are not configurable.
* <p>
* When configuration is needed, an application should either link with
* {@code java.util.logging} - and use the {@code java.util.logging} for
* configuration, or link with {@link LoggerFinder another implementation}
* of the {@link LoggerFinder}
* that provides the necessary configuration.
*
* @apiNote Programmers are not expected to call this class directly.
* Instead they should rely on the static methods defined by {@link
* java.lang.System java.lang.System} or {@link sun.util.logging.PlatformLogger
* sun.util.logging.PlatformLogger}.
*
* @see java.lang.System.LoggerFinder
* @see jdk.internal.logger
* @see sun.util.logging.internal
*
*/
public class DefaultLoggerFinder extends LoggerFinder {
static final RuntimePermission LOGGERFINDER_PERMISSION =
new RuntimePermission("loggerFinder");
Creates a new instance of DefaultLoggerFinder.
Throws: - SecurityException – if the calling code does not have the
RuntimePermission("loggerFinder")
/**
* Creates a new instance of DefaultLoggerFinder.
* @throws SecurityException if the calling code does not have the
* {@code RuntimePermission("loggerFinder")}
*/
protected DefaultLoggerFinder() {
this(checkPermission());
}
private DefaultLoggerFinder(Void unused) {
// nothing to do.
}
private static Void checkPermission() {
final SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(LOGGERFINDER_PERMISSION);
}
return null;
}
// SharedLoggers is a default cache of loggers used when JUL is not
// present - in that case we use instances of SimpleConsoleLogger which
// cannot be directly configure through public APIs.
//
// We can therefore afford to simply maintain two domains - one for the
// system, and one for the application.
//
static final class SharedLoggers {
private final Map<String, Reference<Logger>> loggers =
new HashMap<>();
private final ReferenceQueue<Logger> queue = new ReferenceQueue<>();
synchronized Logger get(Function<String, Logger> loggerSupplier, final String name) {
Reference<? extends Logger> ref = loggers.get(name);
Logger w = ref == null ? null : ref.get();
if (w == null) {
w = loggerSupplier.apply(name);
loggers.put(name, new WeakReference<>(w, queue));
}
// Remove stale mapping...
Collection<Reference<Logger>> values = null;
while ((ref = queue.poll()) != null) {
if (values == null) values = loggers.values();
values.remove(ref);
}
return w;
}
final static SharedLoggers system = new SharedLoggers();
final static SharedLoggers application = new SharedLoggers();
}
public static boolean isSystem(Module m) {
return AccessController.doPrivileged(new PrivilegedAction<>() {
@Override
public Boolean run() {
// returns true if moduleCL is the platform class loader
// or one of its ancestors.
return VM.isSystemDomainLoader(m.getClassLoader());
}
});
}
@Override
public final Logger getLogger(String name, Module module) {
Objects.requireNonNull(name, "name");
Objects.requireNonNull(module, "module");
checkPermission();
return demandLoggerFor(name, module);
}
@Override
public final Logger getLocalizedLogger(String name, ResourceBundle bundle,
Module module) {
return super.getLocalizedLogger(name, bundle, module);
}
Returns a logger
suitable for use within the given module
. Params: - name – The name of the logger.
- module – The module on behalf of which the logger is created.
Throws: - SecurityException – if the calling code does not have the
RuntimePermission("loggerFinder")
.
Implementation Requirements: The default implementation for this method is to return a
simple logger that will print all messages of INFO level and above
to the console. That simple logger is not configurable. Returns: A logger
suitable for the application usage.
/**
* Returns a {@link Logger logger} suitable for use within the
* given {@code module}.
*
* @implSpec The default implementation for this method is to return a
* simple logger that will print all messages of INFO level and above
* to the console. That simple logger is not configurable.
*
* @param name The name of the logger.
* @param module The module on behalf of which the logger is created.
* @return A {@link Logger logger} suitable for the application usage.
* @throws SecurityException if the calling code does not have the
* {@code RuntimePermission("loggerFinder")}.
*/
protected Logger demandLoggerFor(String name, Module module) {
checkPermission();
if (isSystem(module)) {
return SharedLoggers.system.get(SimpleConsoleLogger::makeSimpleLogger, name);
} else {
return SharedLoggers.application.get(SimpleConsoleLogger::makeSimpleLogger, name);
}
}
}