【Java】log日志输出

一、如果是maven项目

    1、pom.xml中加入依赖

<dependency>  
		<groupId>log4j</groupId>  
		<artifactId>log4j</artifactId>  
		<version>1.2.17</version>  
	</dependency>

    2、程序同级目录下（如图）新建log4j.properties文件，内容如下

### set log levels ###
log4j.rootLogger = DEBUG,Console,File

###  Output To Console  ###
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.Target=System.out
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
#log4j.appender.stdout.layout.ConversionPattern = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n
log4j.appender.Console.layout.ConversionPattern= [%p] %d{yyyy-MM-dd HH\:mm\:ss,SSS}  %c{1}:%L - %m%n
#log4j.appender.Console.layout.ConversionPattern= %d{ABSOLUTE} %5p %c{1}:%L - %m%n
#log4j.appender.File.layout.ConversionPattern=[%p][%d{yyyy-MM-dd HH\:mm\:ss,SSS}][%c]%m%n

### Output To File ###
log4j.appender.File=org.apache.log4j.RollingFileAppender 
log4j.appender.File.File=${project}/LogFile/app.log
#log4j.appender.File.DatePattern=_yyyyMMdd'.log'
log4j.appender.File.MaxFileSize=10MB
log4j.appender.File.Threshold=ALL
log4j.appender.File.layout=org.apache.log4j.PatternLayout
log4j.appender.File.layout.ConversionPattern=[%p][%d{yyyy-MM-dd HH\:mm\:ss,SSS}][%c]%m%n

    3、调用方法

import org.apache.log4j.Logger;

class T extends Thread{
	public static Logger log = Logger.getLogger(T.class.getClass());//在不同类下，将本行中的T修改为当前类名即可
	String s;
	public T(String s){
		this.s = s;
	}
	
	public void run(){
		for(int i=0; i<5; i++){
			log.info(s+" "+i);
		}
	}
}

二、非maven项目

    1、下载log4j.jar包

        下载地址：        http://central.maven.org/maven2/log4j/log4j/1.2.17/log4j-1.2.17.jar

    2、其余步骤同上