log4j Tutorial 7, logging Level

The Org.apache.log4j.Level class provides the following levels, but can also be customized by subclasses of the level class.

Level

	Description
All	Levels include custom levels
DEBUG	Specifying fine-grained information events is the most useful debugging for applications
ERROR	Error events may still allow applications to continue running
FATAL	Specifies a very serious error event that could cause the application to abort
INFO	Message that specifies information that can highlight the operation of an application at a coarse-grained level
OFF	This is the highest level, in order to turn off logging
TRACE	Specify less granular information events than debug
WARN	Specify a situation that is potentially harmful

How does the log level work?

Level p levels use Q when logging requests are logged, if P>=Q is enabled. This rule is the core of log4j. It assumes that the level is orderly. They relate to the standard level as follows: All < DEBUG < INFO < WARN < ERROR < FATAL < OFF.

The following example clearly indicates how all debug and info messages can be filtered. This program uses a record and executes the Setlevel (level.x) method to set the required logging level:

This example will print all the messages except debugging and information:

Importorg.apache.log4j.*; Public classLogclass {Private StaticOrg.apache.log4j.Logger log =Logger. GetLogger (Logclass.class);  Public Static voidMain (string[] args) {log.setlevel (Level.warn); Log.trace ("Trace message!"); Log.debug ("Debug message!"); Log.info ("Info message!"); Log.warn ("Warn message!"); Log.error ("Error message!"); Log.fatal ("Fatal message!"); }}

When you compile and run the Logclass program, the following results are produced:

Warn message! Error Message! Fatal Message!

To set the level using the configuration file:

LOG4J provides these to allow programmers to freely change the source code, changing the debug level of the configuration level is based on file settings.

The following is an example of a configuration file using the Log.setlevel (Level.warn) method as shown in the example above.

=/usr/home/= WARN, file# Define the FILE appenderlog4j.appender.FILE=  Org.apache.log4j.FileAppenderlog4j.appender.FILE.File=${log}/ for FILE Appenderlog4j.appender.FILE.layout=  Org.apache.og4j.PatternLayoutlog4j.appender.FILE.layout.conversionPattern=%m%n

Now, use the following program:

Importorg.apache.log4j.*; Public classLogclass {Private StaticOrg.apache.log4j.Logger log =Logger. GetLogger (Logclass.class);  Public Static voidMain (string[] args) {Log.trace ("Trace message!"); Log.debug ("Debug message!"); Log.info ("Info message!"); Log.warn ("Warn message!"); Log.error ("Error message!"); Log.fatal ("Fatal message!"); }}

Now, compile and run the above program to get the following results in the/usr/home/log4j/log.out file:

Warn message! Error Message! Fatal Message!

log4j Tutorial 7, logging Level