网上找了一些资料没看明白,还是找到了一本书,书里有这一章,一步步敲下来。明白了。
PART 1 WEB应用里使用log4j
一、log4j1.2.17下载地址点击打开链接
二、myeclipse中新建WEB项目log4jtest, 并修改web.xml为:
<?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name></display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>log4j config file</servlet-name> <servlet-class>sse.log4j.Log4jInitServlet</servlet-class> <init-param> <param-name>configfile</param-name> <param-value>/WEB-INF/log4jconfig.properties</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> </web-app>
三、新建/WEB-INF/log4jconfig.properties为:
log4j.rootLogger = DEBUG,file log4j.logger.log4jTestLogger=WARN,console,file log4j.appender.console=org.apache.log4j.ConsoleAppender log4j.appender.console.layout=org.apache.log4j.PatternLayout log4j.appender.console.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss,SSS} [%c]-[%p]%m%n log4j.appender.file=org.apache.log4j.RollingFileAppender log4j.appender.file.File=C:/Program Files/Apache Software Foundation/Tomcat 6.0/webapps/log4jtest/WEB-INF/log.html log4j.appender.file.MaxFileSize=500KB log4j.appender.file.MaxBackupIndex=1 log4j.appender.file.layout=org.apache.log4j.HTMLLayout
四、新建sse.log4j.Log4jInitServlet类为:
package sse.log4j; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import org.apache.log4j.PropertyConfigurator; public class Log4jInitServlet extends HttpServlet { @Override public void init() throws ServletException { // TODO Auto-generated method stub super.init(); String path = getServletContext().getRealPath("/"); String configfile = path + getInitParameter("configfile"); PropertyConfigurator.configure(configfile); } }五、新建空文件/WEB-INF/log.html
整个包结构图如下:
六、新建log4japp.jsp,内容如下:
<%@ page language="java" import="org.apache.log4j.Logger" pageEncoding="GB2312"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>log4j application</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body bgcolor="#FFFFFF"> <% Logger rootlogger = Logger.getRootLogger(); Logger log4jlogger = Logger.getLogger("log4jTestLogger"); out.println("rootlogger's LEVEL is "+rootlogger.getLevel()+"<p>"); out.println("log4jlogger's LEVEL is "+log4jlogger.getLevel()+"<p>"); log4jlogger.debug("This is DEBUG info from "+log4jlogger.getName()); log4jlogger.info("This is INFO info from "+log4jlogger.getName()); log4jlogger.warn("This is WARN info from "+log4jlogger.getName()); log4jlogger.error("This is ERROR info from "+log4jlogger.getName()); log4jlogger.fatal("This is FATAL info from "+log4jlogger.getName()); out.println("\nlog info has been printed!"); %> </body> </html>七、启动tomcat,在浏览器中打入URL运行log4japp.jsp,可看到Console的部分输出(原因见参考资料)。
用浏览器打开log.html结果:
PART 2 普通java类里使用log4j
package Test; import org.apache.log4j.Logger; import org.apache.log4j.PropertyConfigurator; public class Test { /* * 步骤: * 一、下载log4j.jar包,并导入 * 二、配置log4j.properties文件 */ private Logger log = Logger.getLogger(Test.class); public Test() { //log4jconfig.properties文件和当前运行的class放在同一目录下 String connectdir=Test.class.getResource("log4jconfig.properties").getPath(); PropertyConfigurator.configure(connectdir); System.out.println(connectdir); } public void testprint() { log.debug("debug test"); log.info("info test"); log.warn("warn test"); log.error("error test"); } public static void main(String[] args) { Test test = new Test(); test.testprint(); } }
log4j参考资料:
参考一
参考二
参考三