org.slf4j.bridge

Class SLF4JBridgeHandler

java.lang.Object

java.util.logging.Handler

org.slf4j.bridge.SLF4JBridgeHandler

public class SLF4JBridgeHandler
extends Handler

Bridge/route all JUL log records to the SLF4J API.

Essentially, the idea is to install on the root logger an instance of SLF4JBridgeHandler as the sole JUL handler in the system. Subsequently, the SLF4JBridgeHandler instance will redirect all JUL log records are redirected to the SLF4J API based on the following mapping of levels:

 FINEST  -> TRACE
 FINER   -> DEBUG
 FINE    -> DEBUG
 INFO    -> INFO
 WARNING -> WARN
 SEVER   -> ERROR
 

Usage:

 // call only once during initialization time of your application
 SLF4JBridgeHandler.install();

 // usual pattern: get a Logger and then log a message
 java.util.logging.Logger julLogger = java.util.logging.Logger
     .getLogger("org.wombat");
 julLogger.fine("hello world"); // this will get redirected to SLF4J
 

Please note that translating a java.util.logging event into SLF4J incurs the cost of constructing LogRecord instance regardless of whether the SLF4J logger is disabled for the given level. Consequently, j.u.l. to SLF4J translation can seriously impact on the cost of disabled logging statements (60 fold increase) and a measurable impact on enabled log statements (20% overall increase).

If application performance is a concern, then use of SLF4JBridgeHandler is appropriate only if few j.u.l. logging statements are in play.

Since:

1.5.1

Author:

Christian Stein, Joern Huxhorn, Ceki Gülcü, Darryl Smith, James R. Perkins

Constructor Summary

Constructors

Constructor and Description
SLF4JBridgeHandler() Initialize this handler.

Method Summary

Modifier and Type	Method and Description
protected void	callLocationAwareLogger(LocationAwareLogger lal, LogRecord record)
protected void	callPlainSLF4JLogger(Logger slf4jLogger, LogRecord record)
void	close() No-op implementation.
void	flush() No-op implementation.
protected Logger	getSLF4JLogger(LogRecord record) Return the Logger instance that will be used for logging.
static void	install() Adds a SLF4JBridgeHandler instance to jul's root logger.
static boolean	isInstalled() Returns true if SLF4JBridgeHandler has been previously installed, returns false otherwise.
void	publish(LogRecord record) Publish a LogRecord.
static void	removeHandlersForRootLogger() Invoking this method removes/unregisters/detaches all handlers currently attached to the root logger
static void	uninstall() Removes previously installed SLF4JBridgeHandler instances.

Methods inherited from class java.util.logging.Handler

getEncoding, getErrorManager, getFilter, getFormatter, getLevel, isLoggable, reportError, setEncoding, setErrorManager, setFilter, setFormatter, setLevel

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SLF4JBridgeHandler

public SLF4JBridgeHandler()

Initialize this handler.

Method Detail

install

public static void install()

Adds a SLF4JBridgeHandler instance to jul's root logger.

This handler will redirect jul logging to SLF4J. However, only logs enabled in j.u.l. will be redirected. For example, if a log statement invoking a j.u.l. logger disabled that statement, by definition, will not reach any SLF4JBridgeHandler instance and cannot be redirected.

uninstall

public static void uninstall()
                      throws SecurityException

Removes previously installed SLF4JBridgeHandler instances. See also install().

Throws:

SecurityException - A SecurityException is thrown, if a security manager exists and if the caller does not have LoggingPermission("control").

isInstalled

public static boolean isInstalled()
                           throws SecurityException

Returns true if SLF4JBridgeHandler has been previously installed, returns false otherwise.

Returns:

Throws:

SecurityException

removeHandlersForRootLogger

public static void removeHandlersForRootLogger()

Invoking this method removes/unregisters/detaches all handlers currently attached to the root logger

Since:

1.6.5

close

public void close()

No-op implementation.

Specified by:

close in class Handler

flush

public void flush()

No-op implementation.

Specified by:

flush in class Handler

getSLF4JLogger

protected Logger getSLF4JLogger(LogRecord record)

Return the Logger instance that will be used for logging.

callLocationAwareLogger

protected void callLocationAwareLogger(LocationAwareLogger lal,
                                       LogRecord record)

callPlainSLF4JLogger

protected void callPlainSLF4JLogger(Logger slf4jLogger,
                                    LogRecord record)

publish

public void publish(LogRecord record)

Publish a LogRecord.

The logging request was made initially to a Logger object, which initialized the LogRecord and forwarded it here.

This handler ignores the Level attached to the LogRecord, as SLF4J cares about discarding log statements.

Specified by:

publish in class Handler

Parameters:

record - Description of the log event. A null record is silently ignored and is not published.