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 SEVERE -> ERROR
Programmatic installation:
// Optionally remove existing handlers attached to j.u.l root logger SLF4JBridgeHandler.removeHandlersForRootLogger(); // (since SLF4J 1.6.5) // add SLF4JBridgeHandler to j.u.l's root logger, should be done once during // the initialization phase of your application SLF4JBridgeHandler.install();
Installation via logging.properties configuration file:
// register SLF4JBridgeHandler as handler for the j.u.l. root logger handlers = org.slf4j.bridge.SLF4JBridgeHandler
Once SLF4JBridgeHandler is installed, logging by j.u.l. loggers will be directed to SLF4J. Example:
import java.util.logging.Logger; ... // usual pattern: get a Logger and then log a message Logger julLogger = 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 increase the cost of disabled logging
statements (60 fold or 6000% increase) and measurably impact the performance of enabled log
statements (20% overall increase). Please note that as of logback-version 0.9.25,
it is possible to completely eliminate the 60-fold translation overhead for disabled
log statements with the help of LevelChangePropagator.
If you are concerned about application performance, then use of SLF4JBridgeHandler
is appropriate only if any of the following conditions is true:
Given that to is a reserved keyword under Java 9 within module productions, the MANIFEST.MF file in jul-to-slf4j.jar declares jul_to_slf4j as its Automatic Module Name. Thus, if your application is Jigsaw modularized, the requires statement in your module-info.java needs to be jul_to_slf4j (note the two underscores).
Constructor and Description |
---|
SLF4JBridgeHandler()
Initialize this handler.
|
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.
|
getEncoding, getErrorManager, getFilter, getFormatter, getLevel, isLoggable, reportError, setEncoding, setErrorManager, setFilter, setFormatter, setLevel
public SLF4JBridgeHandler()
public static void install()
This handler will redirect j.u.l. 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 is disabled, then the corresponding non-event will not reach SLF4JBridgeHandler and cannot be redirected.
public static void uninstall() throws SecurityException
install()
.SecurityException
- A SecurityException
is thrown, if a security manager
exists and if the caller does not have
LoggingPermission("control").public static boolean isInstalled()
public static void removeHandlersForRootLogger()
protected Logger getSLF4JLogger(LogRecord record)
record
- a LogRecordprotected void callLocationAwareLogger(LocationAwareLogger lal, LogRecord record)
protected void callPlainSLF4JLogger(Logger slf4jLogger, LogRecord record)
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