16.log4j.properties例子:log4j.appender.stdout.Target

package com.toogen.log4j;

import org.apache.log4j.Level;
import org.apache.log4j.Logger;

public class HelloLog4JToogen {
	// 构造记录器,形参是记录器所在的类,表示要在该类做日志
	private static Logger logger = Logger.getLogger(HelloLog4JToogen.class);
	/** 
	 * @param args
	 */
	public static void main(String[] args) {
		getMessage();
	}
	
	private static void getMessage() {
		// 记录下各种级别的信息,这些信息放在哪儿,以哪种方式存放,在log4j.properties文件中配置.
		if (logger.isDebugEnabled()) {
			logger.debug("This is debug message.");
		}
		if (logger.isInfoEnabled()) {
			logger.info("This is a info message.");
		}
		if (logger.isEnabledFor(Level.WARN)) {
			logger.warn("This is a warn message.");
		}
		if (logger.isEnabledFor(Level.ERROR)) {
			logger.error("This is a error message.....");
			System.err.println();
		}
	}

}
           

log4j.rootLogger=info,stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.TTCCLayout
           

[main] INFO com.toogen.log4j.HelloLog4JToogen - This is a info message.
[main] WARN com.toogen.log4j.HelloLog4JToogen - This is a warn message.
[main] ERROR com.toogen.log4j.HelloLog4JToogen - This is a error message.....

总结:log4j.appender.stdout.Target=System.out,意味着控制台输出标准信息,log4j.appender.stdout.Target=System.err输出错误信息