Java中Log4j的入门实例

1、新建一个Java工程，导入包log4j-1.2.17.jar。

2、src同级创建并设置log4j.properties，内容如下

 ### 设置###
log4j.rootLogger = debug,stdout,D,E

### 输出信息到控制抬 ###
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n

### 输出DEBUG 级别以上的日志到=E://logs/error.log ###
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = E://logs/log.log
log4j.appender.D.Append = true
log4j.appender.D.Threshold = DEBUG 
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

### 输出ERROR 级别以上的日志到=E://logs/error.log ###
log4j.appender.E = org.apache.log4j.DailyRollingFileAppender
log4j.appender.E.File =E://logs/error.log 
log4j.appender.E.Append = true
log4j.appender.E.Threshold = ERROR 
log4j.appender.E.layout = org.apache.log4j.PatternLayout
log4j.appender.E.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

3、设置日志内容

package com.log4jTest;

import org.apache.log4j.Logger;

public class Test {
    private static Logger logger = Logger.getLogger(Test.class);  

    public static void main(String[] args) {  

        // 记录debug级别的信息  
        logger.debug("This is debug message.");  

        // 记录info级别的信息  
        logger.info("This is info message.");  

        // 记录error级别的信息  
        logger.error("This is error message.");  
    }  
}

控制台输出结果

[DEBUG] 2016-08-14 14:30:19,852 method:com.log4jTest.Test.main(Test.java:34)
This is debug message.
[INFO ] 2016-08-14 14:30:19,858 method:com.log4jTest.Test.main(Test.java:36)
This is info message.
[ERROR] 2016-08-14 14:30:19,858 method:com.log4jTest.Test.main(Test.java:38)
This is error message.　　

log.log文件输出结果

2016-08-14 14:47:23  [ main:0 ] - [ DEBUG ]  This is debug message.
2016-08-14 14:47:23  [ main:5 ] - [ INFO ]  This is info message.
2016-08-14 14:47:23  [ main:5 ] - [ ERROR ]  This is error message.　　

error.log文件输出结果

2016-08-14 14:47:23  [ main:5 ] - [ ERROR ]  This is error message.