Log4j Study (ON)

CSDN has a lot of examples and tutorials on log4j, some are very good, but in order to consolidate knowledge, I also write a bar.





my request to log4j is not very high, mainly has two uses





one) How to use log4j and common-logging packages in Web applications;


II) How ordinary Java applications use log4j and common-logging packages;





first summarize the simple, how to use log4j and common-logging packages in a common Java application





steps are as follows:


1) Add Log4j.jar and Common-logging.jar two packages to environment variables or classpath





2) Write Log4j.xml file, for example:





<?xml version= "1.0" encoding= "UTF-8" >


<! DOCTYPE log4j:configuration SYSTEM "Log4j.dtd" >





<log4j:configuration xmlns:log4j= "http://jakarata.apache.org/log4j/" >





<appender name= "file" class= "Org.apache.log4j.RollingFileAppender" >


<param name= "File" value= "Log.log"/>


<layout class= "Org.apache.log4j.PatternLayout" >


<param name= "Conversionpattern" value= "%d [%t]%p-%m%n"/>


</layout>


</appender>





<logger name= "Com.log4j.test.test" additivity= "false" >


<level value= "Debug"/>


<appender-ref ref= "file"/>


</logger>





<root>


<level value= "info"/>


<appender-ref ref= "file"/>


</root>





</log4j:configuration>





3) Program use method:


package com.log4j.test;





import Org.apache.log4j.xml.DOMConfigurator;





import org.apache.commons.logging.*;








class configlog4j


{


public static void config ()


{


domconfigurator.configure ("Config/log4j.xml");


}


}


public class Testlog4j {


Private log log =logfactory.getlog (Testlog4j.class);





public testlog4j () {


Configlog4j.config ();





}





public void TestPrint1 ()


{


log.debug ("Debug Test");


log.info ("info test");


Log.warn ("Warn Test");


log.error ("Error test");


}





public static void Main (string[] args)


{


testlog4j test = new testlog4j ();


test.testprint1 ();





}





}





OK! This will print the message as required.





additional LOG4J.DTD





log4j:configuration


|


+--Appender (Name, Class)


| |


| +--param (name, value)


| +--layout (Class)


| |


| +--param (name, value)


+--Logger (name, additivity)


| |


| +--level (class, value)


| | |


| | +--param (name, value)


| +--appender-ref (ref)


+--Root


|


+--param (Name, Class)


+--level


| |


| +--param (name, value)


+--appender-ref (ref)








output format definition:


%m The message specified in the output code


-%p Output Priority


%r Output The number of milliseconds it takes to output the log information

The
%c output belongs to the class, usually the full name of the class in which it is located


%t Output The thread name that generated the log event


%n output A carriage return line break, the Windows platform is "\ r \ n" and the UNIX platform is "\ n"


%d output log point-in-time date or time, the default format is ISO8601, or you can specify a format after it, such as:%d{yyy MMM dd hh:mm:ss,sss}, Output is similar: October 18, 2002 22:10:28, 921


%l where the output log event occurs, including the class name, the thread that occurred, and the number of lines in the code. Generally used it does not need to use%c.