JAVA日志信息输出到指定地方

TOC

1. 使用idea建一个maven项目，最终目录结构如下：
   

2. pom.xml中引入log4j依赖：
   

 
      log4j
      log4j
      1.2.17
    

3. 在resources目录下新建log4j.properties：

log4j.rootLogger = debug,stdout,D,E  

log4j.appender.stdout = org.apache.log4j.ConsoleAppender  ### 输出信息到控制抬 ###
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  

log4j.appender.D = org.apache.log4j.DailyRollingFileAppender  ### 输出DEBUG 级别以上的日志到=E://logs/log.log ###
log4j.appender.D.File = F://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 = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n 

log4j.appender.E = org.apache.log4j.DailyRollingFileAppender  ### 输出ERROR 级别以上的日志到=E://logs/error.log ###
log4j.appender.E.File =F://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 = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n

4. web.xml配置：

    Log4JTestServlet
    com.test.log4j.Log4JTestServlet
  

  
  
    Log4JInitServlet
    com.test.log4j.Log4JInitServlet
    
      log4j-properties-location
      /WEB-INF/classes/log4j.properties
    
    1
  

  
    Log4JTestServlet
    /test
  

5. web容器初始化servlet：

package com.test.log4j;

import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.PropertyConfigurator;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;

/**
 * @author
 * @comment
 * @date
 * @modifyUser
 * @modifyDate
 * @modifyDesc
 */
@WebServlet("/Log4JInitServlet")
public class Log4JInitServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Log4JInitServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see Servlet#init(ServletConfig)
     */
    public void init(ServletConfig config) throws ServletException {
        System.out.println("Log4JInitServlet 正在初始化 log4j日志设置信息");
        String log4jLocation = config.getInitParameter("log4j-properties-location");

        ServletContext sc = config.getServletContext();

        if (log4jLocation == null) {
            System.err.println("*** 没有 log4j-properties-location 初始化的文件, 所以使用 BasicConfigurator初始化");
            BasicConfigurator.configure();
        } else {
            String webAppPath = sc.getRealPath("/");
            String log4jProp = webAppPath + log4jLocation;
            File yoMamaYesThisSaysYoMama = new File(log4jProp);
            if (yoMamaYesThisSaysYoMama.exists()) {
                System.out.println("使用: " + log4jProp+"初始化日志设置信息");
                PropertyConfigurator.configure(log4jProp);
            } else {
                System.err.println("*** " + log4jProp + " 文件没有找到， 所以使用 BasicConfigurator初始化");
                BasicConfigurator.configure();
            }
        }
        super.init(config);
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }
}

6. 测试servlet

package com.test.log4j;

import org.apache.log4j.Logger;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @author
 * @comment
 * @date
 * @modifyUser
 * @modifyDate
 * @modifyDesc
 */
@WebServlet("/Log4JTestServlet")
public class Log4JTestServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private static Logger logger = Logger.getLogger(Log4JTestServlet.class);

    /**
     * @see HttpServlet#HttpServlet()
     */
    public Log4JTestServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see Servlet#init(ServletConfig)
     */
    public void init(ServletConfig config) throws ServletException {
        // TODO Auto-generated method stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 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.");
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }
}

7. 启动web项目，进行测试：
   
   
   
8. 参考大神链接：
   https://www.cnblogs.com/shuiyelifang/p/5823207.html