org.apache.log4j
Class Logger

java.lang.Object
  org.apache.log4j.Logger

public class Logger
extends java.lang.Object

This is the central class in the log4j package. Most logging operations, except configuration, are done through this class.

NOTE: This is NOT the original file of Log4J Logger, and is only here to provide a static mapping to the Pax Logging system running under OSGi.

The client code that wishes to use this adaptation of Log4J and have the log output to be directed to the Pax Logging Service backend, which is driven by the real Log4J, it is necessary to;

• ensure that log4j.jar is NOT included in your bundle jar.
• include the pax-logging-client.jar into the client bundle.
• update your Manifest.MF to import the org.ops4j.pax.logging package.
• Initiate this class by setting the Bundle Context.

Author:

Ceki Gülcü, Niclas Hedhman

Method Summary

void	debug(java.lang.Object message) Log a message object with the DEBUG level.
void	debug(java.lang.Object messagePattern, java.lang.Object arg) Log a message with the DEBUG level with message formatting done according to the value of messagePattern and arg parameters.
void	debug(java.lang.Object message, java.lang.Throwable t) Log a message object with the DEBUG level including the stack trace of the Throwablet passed as parameter.
void	debug(java.lang.String messagePattern, java.lang.Object arg1, java.lang.Object arg2) Log a message with the DEBUG level with message formatting done according to the messagePattern and the arguments arg1 and arg2.
void	error(java.lang.Object message) Log a message object with the ERROR Level.
void	error(java.lang.Object messagePattern, java.lang.Object arg) Log a message with the ERROR level with message formatting done according to the value of messagePattern and arg parameters.
void	error(java.lang.Object message, java.lang.Throwable t) Log a message object with the ERROR level including the stack trace of the Throwablet passed as parameter.
void	error(java.lang.String messagePattern, java.lang.Object arg1, java.lang.Object arg2) Log a message with the ERROR level with message formatting done according to the messagePattern and the arguments arg1 and arg2.
void	fatal(java.lang.Object message) Log a message object with the FATAL Level.
void	fatal(java.lang.Object messagePattern, java.lang.Object arg) Log a message with the FATAL level with message formatting done according to the value of messagePattern and arg parameters.
void	fatal(java.lang.Object message, java.lang.Throwable t) Log a message object with the FATAL level including the stack trace of the Throwablet passed as parameter.
void	fatal(java.lang.String messagePattern, java.lang.Object arg1, java.lang.Object arg2) Log a message with the FATAL level with message formatting done according to the messagePattern and the arguments arg1 and arg2.
static Logger	getLogger(java.lang.Class clazz) Shorthand for getLogger(clazz.getName()).
static Logger	getLogger(java.lang.String name) Retrieve a logger by name.
static Logger	getLogger(java.lang.String name, LoggerFactory factory) This method is equivalent to getLogger( String name ) and the LoggerFactory is ignored.
static Logger	getRootLogger() Return the root of logger for the current hierarchy.
void	info(java.lang.Object message) Log a message object with the INFO Level.
void	info(java.lang.Object messagePattern, java.lang.Object arg) Log a message with the INFO level with message formatting done according to the value of messagePattern and arg parameters.
void	info(java.lang.Object message, java.lang.Throwable t) Log a message object with the INFO level including the stack trace of the Throwablet passed as parameter.
void	info(java.lang.String messagePattern, java.lang.Object arg1, java.lang.Object arg2) Log a message with the INFO level with message formatting done according to the messagePattern and the arguments arg1 and arg2.
boolean	isDebugEnabled() Check whether this category is enabled for the DEBUG Level.
boolean	isEnabledFor(Priority priority) Check whether this category is enabled for the given Level.
boolean	isErrorEnabled() Check whether this category is enabled for the ERROR Level.
boolean	isInfoEnabled() Check whether this category is enabled for the info Level.
boolean	isTraceEnabled() Check whether this category is enabled for the TRACE Level.
boolean	isWarnEnabled() Check whether this category is enabled for the WARN Level.
void	log(Priority priority, java.lang.Object msg) Log a message with the code level priority.
void	log(Priority priority, java.lang.Object message, java.lang.Throwable t) This generic form is intended to be used by wrappers.
void	log(java.lang.String callerFQCN, Priority level, java.lang.Object message, java.lang.Throwable t) This is the most generic printing method.
static void	release() Lifecycle method to release any resources held.
static void	setBundleContext(org.osgi.framework.BundleContext ctx)
void	trace(java.lang.Object message) Log a message object with the TRACE level.
void	trace(java.lang.Object messagePattern, java.lang.Object arg) Log a message with the TRACE level with message formatting done according to the value of messagePattern and arg parameters.
void	trace(java.lang.Object message, java.lang.Throwable t) Log a message object with the TRACE level including the stack trace of the Throwablet passed as parameter.
void	trace(java.lang.String messagePattern, java.lang.Object arg1, java.lang.Object arg2) Log a message with the TRACE level with message formatting done according to the messagePattern and the arguments arg1 and arg2.
void	warn(java.lang.Object message) Log a message object with the WARN Level.
void	warn(java.lang.Object messagePattern, java.lang.Object arg) Log a message with the WARN level with message formatting done according to the value of messagePattern and arg parameters.
void	warn(java.lang.Object message, java.lang.Throwable t) Log a message with the WARN level including the stack trace of the Throwablet passed as parameter.
void	warn(java.lang.String messagePattern, java.lang.Object arg1, java.lang.Object arg2) Log a message with the WARN level with message formatting done according to the messagePattern and the arguments arg1 and arg2.

Methods inherited from class java.lang.Object

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

Method Detail

setBundleContext

public static void setBundleContext(org.osgi.framework.BundleContext ctx)

release

public static void release()

Lifecycle method to release any resources held.

getLogger

public static Logger getLogger(java.lang.String name)

Retrieve a logger by name. If the named logger already exists, then the existing instance will be reutrned. Otherwise, a new instance is created.

By default, loggers do not have a set level but inherit it from their ancestors. This is one of the central features of log4j.

Parameters:

name - The name of the logger to retrieve.

Returns:

the Logger instance of the given name.

getLogger

public static Logger getLogger(java.lang.Class clazz)

Shorthand for getLogger(clazz.getName()).

Parameters:

clazz - The name of clazz will be used as the name of the logger to retrieve. See getLogger(String) for more detailed information.

Returns:

the Logger instance for the given class.

getRootLogger

public static Logger getRootLogger()

Return the root of logger for the current hierarchy.

The root logger is always instantiated and available. It's name is "root".

Nevertheless, note that calling Logger.getLogger("root") does not retrieve the root logger but a logger just under root named "root".

Returns:

the top-most Logger instance, which does not have a name.

getLogger

public static Logger getLogger(java.lang.String name,
                               LoggerFactory factory)

This method is equivalent to getLogger( String name ) and the LoggerFactory is ignored. The method exists only to improve compatibility with Log4J.

Parameters:

name - The name of the logger to retrieve.

factory - Ignored!

Returns:

the Logger instance of the given name.

Since:

Pax Logging 0.9.5

trace

public void trace(java.lang.Object message)

Log a message object with the TRACE level.

Parameters:

message - the message object to log.

Since:

1.2.12

See Also:

for an explanation of the logic applied.

trace

public void trace(java.lang.Object message,
                  java.lang.Throwable t)

Log a message object with the TRACE level including the stack trace of the Throwablet passed as parameter.

See debug(Object) form for more detailed information.

Parameters:

message - the message object to log.

t - the exception to log, including its stack trace.

Since:

1.2.12

trace

public void trace(java.lang.Object messagePattern,
                  java.lang.Object arg)

Log a message with the TRACE level with message formatting done according to the value of messagePattern and arg parameters.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg - The argument to replace the formatting element, i,e, the '{}' pair within messagePattern.

Since:

1.3

trace

public void trace(java.lang.String messagePattern,
                  java.lang.Object arg1,
                  java.lang.Object arg2)

Log a message with the TRACE level with message formatting done according to the messagePattern and the arguments arg1 and arg2.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg1 - The first argument to replace the first formatting element

arg2 - The second argument to replace the second formatting element

Since:

1.3

fatal

public void fatal(java.lang.String messagePattern,
                  java.lang.Object arg1,
                  java.lang.Object arg2)

Log a message with the FATAL level with message formatting done according to the messagePattern and the arguments arg1 and arg2.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg1 - The first argument to replace the first formatting element

arg2 - The second argument to replace the second formatting element

Since:

1.3

debug

public void debug(java.lang.Object message)

Log a message object with the DEBUG level.

This method first checks if this category is DEBUG enabled by comparing the level of this category with the DEBUG level. If this category is DEBUG enabled, then it converts the message object (passed as parameter) to a string by invoking the appropriate org.apache.log4j.or.ObjectRenderer. It then proceeds to call all the registered appenders in this category and also higher in the hierarchy depending on the value of the additivity flag.

WARNING Note that passing a Throwable to this method will print the name of the Throwable but no stack trace. To print a stack trace use the debug(Object,Throwable) form instead.

Parameters:

message - the message object to log.

debug

public void debug(java.lang.Object message,
                  java.lang.Throwable t)

Log a message object with the DEBUG level including the stack trace of the Throwablet passed as parameter.

See debug(Object) form for more detailed information.

Parameters:

message - the message object to log.

t - the exception to log, including its stack trace.

debug

public void debug(java.lang.Object messagePattern,
                  java.lang.Object arg)

Log a message with the DEBUG level with message formatting done according to the value of messagePattern and arg parameters.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg - The argument to replace the formatting element, i,e, the '{}' pair within messagePattern.

Since:

1.3

debug

public void debug(java.lang.String messagePattern,
                  java.lang.Object arg1,
                  java.lang.Object arg2)

Log a message with the DEBUG level with message formatting done according to the messagePattern and the arguments arg1 and arg2.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg1 - The first argument to replace the first formatting element

arg2 - The second argument to replace the second formatting element

Since:

1.3

isErrorEnabled

public boolean isErrorEnabled()

Check whether this category is enabled for the ERROR Level. See also isDebugEnabled().

Returns:

boolean - true if this category is enabled for level ERROR, false otherwise.

error

public void error(java.lang.Object message)

Log a message object with the ERROR Level.

This method first checks if this category is ERROR enabled by comparing the level of this category with ERROR Level. If this category is ERROR enabled, then it converts the message object passed as parameter to a string by invoking the appropriate org.apache.log4j.or.ObjectRenderer. It proceeds to call all the registered appenders in this category and also higher in the hierarchy depending on the value of the additivity flag.

WARNING Note that passing a Throwable to this method will print the name of the Throwable but no stack trace. To print a stack trace use the error(Object,Throwable) form instead.

Parameters:

message - the message object to log

error

public void error(java.lang.Object message,
                  java.lang.Throwable t)

Log a message object with the ERROR level including the stack trace of the Throwablet passed as parameter.

See error(Object) form for more detailed information.

Parameters:

message - the message object to log.

t - the exception to log, including its stack trace.

error

public void error(java.lang.Object messagePattern,
                  java.lang.Object arg)

Log a message with the ERROR level with message formatting done according to the value of messagePattern and arg parameters.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg - The argument to replace the formatting element, i,e, the '{}' pair within messagePattern.

Since:

1.3

error

public void error(java.lang.String messagePattern,
                  java.lang.Object arg1,
                  java.lang.Object arg2)

Log a message with the ERROR level with message formatting done according to the messagePattern and the arguments arg1 and arg2.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg1 - The first argument to replace the first formatting element

arg2 - The second argument to replace the second formatting element

Since:

1.3

fatal

public void fatal(java.lang.Object message)

Log a message object with the FATAL Level.

This method first checks if this category is FATAL enabled by comparing the level of this category with FATAL Level. If the category is FATAL enabled, then it converts the message object passed as parameter to a string by invoking the appropriate org.apache.log4j.or.ObjectRenderer. It proceeds to call all the registered appenders in this category and also higher in the hierarchy depending on the value of the additivity flag.

WARNING Note that passing a Throwable to this method will print the name of the Throwable but no stack trace. To print a stack trace use the fatal(Object,Throwable) form instead.

Parameters:

message - the message object to log

fatal

public void fatal(java.lang.Object messagePattern,
                  java.lang.Object arg)

Log a message with the FATAL level with message formatting done according to the value of messagePattern and arg parameters.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg - The argument to replace the formatting element, i,e, the '{}' pair within messagePattern.

Since:

1.3

fatal

public void fatal(java.lang.Object message,
                  java.lang.Throwable t)

Log a message object with the FATAL level including the stack trace of the Throwablet passed as parameter.

See fatal(Object) for more detailed information.

Parameters:

message - the message object to log.

t - the exception to log, including its stack trace.

info

public void info(java.lang.Object message)

Log a message object with the INFO Level.

This method first checks if this category is INFO enabled by comparing the level of this category with INFO Level. If the category is INFO enabled, then it converts the message object passed as parameter to a string by invoking the appropriate org.apache.log4j.or.ObjectRenderer. It proceeds to call all the registered appenders in this category and also higher in the hierarchy depending on the value of the additivity flag.

WARNING Note that passing a Throwable to this method will print the name of the Throwable but no stack trace. To print a stack trace use the info(Object,Throwable) form instead.

Parameters:

message - the message object to log

info

public void info(java.lang.Object messagePattern,
                 java.lang.Object arg)

Log a message with the INFO level with message formatting done according to the value of messagePattern and arg parameters.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg - The argument to replace the formatting element, i,e, the '{}' pair within messagePattern.

Since:

1.3

info

public void info(java.lang.String messagePattern,
                 java.lang.Object arg1,
                 java.lang.Object arg2)

Log a message with the INFO level with message formatting done according to the messagePattern and the arguments arg1 and arg2.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg1 - The first argument to replace the first formatting element

arg2 - The second argument to replace the second formatting element

Since:

1.3

info

public void info(java.lang.Object message,
                 java.lang.Throwable t)

Log a message object with the INFO level including the stack trace of the Throwablet passed as parameter.

See info(Object) for more detailed information.

Parameters:

message - the message object to log.

t - the exception to log, including its stack trace.

isDebugEnabled

public boolean isDebugEnabled()

Check whether this category is enabled for the DEBUG Level.

This function is intended to lessen the computational cost of disabled log debug statements.

For some cat Category object, when you write,

      cat.debug("This is entry number: " + i );
  

You incur the cost constructing the message, concatenatiion in this case, regardless of whether the message is logged or not.

If you are worried about speed, then you should write

          if(cat.isDebugEnabled()) {
            cat.debug("This is entry number: " + i );
          }
  

This way you will not incur the cost of parameter construction if debugging is disabled for cat. On the other hand, if the cat is debug enabled, you will incur the cost of evaluating whether the category is debug enabled twice. Once in isDebugEnabled and once in the debug. This is an insignificant overhead since evaluating a category takes about 1%% of the time it takes to actually log.

Returns:

boolean - true if this category is debug enabled, false otherwise.

isTraceEnabled

public boolean isTraceEnabled()

Check whether this category is enabled for the TRACE Level. See also isDebugEnabled().

Returns:

boolean - true if this category is enabled for level TRACE, false otherwise.

isInfoEnabled

public boolean isInfoEnabled()

Check whether this category is enabled for the info Level. See also isDebugEnabled().

Returns:

boolean - true if this category is enabled for level info, false otherwise.

isWarnEnabled

public boolean isWarnEnabled()

Check whether this category is enabled for the WARN Level. See also isDebugEnabled().

Returns:

boolean - true if this category is enabled for level WARN, false otherwise.

isEnabledFor

public boolean isEnabledFor(Priority priority)

Check whether this category is enabled for the given Level.

Parameters:

priority - the level to check

Returns:

boolean - true if this category is enabled for the given level, false otherwise.

warn

public void warn(java.lang.Object message)

Log a message object with the WARN Level.

This method first checks if this category is WARN enabled by comparing the level of this category with WARN Level. If the category is WARN enabled, then it converts the message object passed as parameter to a string by invoking the appropriate org.apache.log4j.or.ObjectRenderer. It proceeds to call all the registered appenders in this category and also higher in the hieararchy depending on the value of the additivity flag.

WARNING Note that passing a Throwable to this method will print the name of the Throwable but no stack trace. To print a stack trace use the warn(Object,Throwable) form instead.

Parameters:

message - the message object to log.

warn

public void warn(java.lang.Object message,
                 java.lang.Throwable t)

Log a message with the WARN level including the stack trace of the Throwablet passed as parameter.

See warn(Object) for more detailed information.

Parameters:

message - the message object to log.

t - the exception to log, including its stack trace.

warn

public void warn(java.lang.Object messagePattern,
                 java.lang.Object arg)

Log a message with the WARN level with message formatting done according to the value of messagePattern and arg parameters.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg - The argument to replace the formatting element, i,e, the '{}' pair within messagePattern.

Since:

1.3

warn

public void warn(java.lang.String messagePattern,
                 java.lang.Object arg1,
                 java.lang.Object arg2)

Log a message with the WARN level with message formatting done according to the messagePattern and the arguments arg1 and arg2.

This form avoids superflous parameter construction. Whenever possible, you should use this form instead of constructing the message parameter using string concatenation.

Parameters:

messagePattern - The message pattern which will be parsed and formatted

arg1 - The first argument to replace the first formatting element

arg2 - The second argument to replace the second formatting element

Since:

1.3

log

public void log(Priority priority,
                java.lang.Object msg)

Log a message with the code level priority.

Parameters:

priority, - the code level of the message

msg - the message object to log.

log

public void log(Priority priority,
                java.lang.Object message,
                java.lang.Throwable t)

This generic form is intended to be used by wrappers.

log

public void log(java.lang.String callerFQCN,
                Priority level,
                java.lang.Object message,
                java.lang.Throwable t)

This is the most generic printing method. It is intended to be invoked by wrapper classes. Note:In Pax Logging the callerFQCN is ignored.

Parameters:

callerFQCN - The wrapper class' fully qualified class name.

level - The level of the logging request.

message - The message of the logging request.

t - The throwable of the logging request, may be null.