pom.xml中添加依赖。

    	
     
      log4j
     	
     
      log4j
     	
     
      1.2.17
     
    

maven会自动添加相应的jar包

配置log4j初始化用的servlet

web.xml中添加下面servlet

    	
     
      log4j-init
     	
     
      com.suyang.servlet.Log4jInit
     	
     		
      
       log4j-init-file
      		
      
       \WEB-INF\classes\log4j.properties
      	
     	
     
      1
     
    

添加对应的servlet

Log4jInit.java

package com.suyang.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.log4j.PropertyConfigurator;/** * Servlet implementation class Log4jInit */public class Log4jInit extends HttpServlet {	private static final long serialVersionUID = 1L;	@Override	protected void doGet(HttpServletRequest req, HttpServletResponse resp)			throws ServletException, IOException {		// TODO Auto-generated method stub		super.doGet(req, resp);	}	@Override	protected void doPost(HttpServletRequest req, HttpServletResponse resp)			throws ServletException, IOException {		// TODO Auto-generated method stub		super.doPost(req, resp);	}	@Override	public void init() throws ServletException {		// TODO Auto-generated method stub		super.init();		String prefix = getServletContext().getRealPath("/");		String file = getInitParameter("log4j-init-file");		if (file != null) {			System.out.println("read log4j.properties:"+prefix + file);			PropertyConfigurator.configure(prefix + file);		}	}}

在resources中添加log4j.properties文件，maven会自动把文件复制到classes目录下

log4j.rootLogger = DEBUG , stdout , Dlog4j.appender.stdout = org.apache.log4j.ConsoleAppenderlog4j.appender.stdout.Target = System.outlog4j.appender.stdout.layout = org.apache.log4j.PatternLayoutlog4j.appender.stdout.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss} [ %t:%r ] - [ %p ] %m%nlog4j.appender.D = org.apache.log4j.DailyRollingFileAppenderlog4j.appender.D.Threshold= DEBUGlog4j.appender.D.File= ${catalina.home}/logs/log.loglog4j.appender.D.ImmediateFlush= truelog4j.appender.D.Append= truelog4j.appender.D.DatePattern='-'yyyy-MM-dd-HH'.log'log4j.appender.D.Encoding= UTF-8log4j.appender.D.layout= org.apache.log4j.PatternLayoutlog4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss} [ %t:%r ] - [ %p ] %m%n

日志会自动记录DEBUG级别以上的日志。