Java Web Project自定义错误页面，log4j记录日志。

创建记录日志的文件LoggerHelper.java:

 package com.wyp.helper;

 import org.apache.log4j.Logger;

 public class LoggerHelper {
     private static Logger _logger = Logger.getLogger(LoggerHelper.class);
     private static String newLine = System.getProperty("line.separator");

     public static void info(Logger logger, String message) {
         logger.info(newLine);
         logger.info(message);
     }

     public static void info(Logger logger, String message, Throwable exception) {
         logger.info(newLine);
         logger.info(message, exception);
     }

     public static void debug(Logger logger, String message) {
         logger.debug(newLine);
         logger.debug(message);
     }

     public static void debug(Logger logger, String message, Throwable exception) {
         logger.debug(newLine);
         logger.debug(message, exception);
     }

     public static void error(Logger logger, String message) {
         logger.error(newLine);
         logger.error(message);
     }

     public static void error(Logger logger, String message, Throwable exception) {
         logger.error(newLine);
         logger.error(message, exception);
     }

     public static void info(String message) {
         _logger.info(newLine);
         _logger.info(message);
     }

     public static void info(String message, Throwable exception) {
         _logger.info(newLine);
         _logger.info(message, exception);
     }

     public static void debug(String message) {
         _logger.debug(newLine);
         _logger.debug(message);
     }

     public static void debug(String message, Throwable exception) {
         _logger.debug(newLine);
         _logger.debug(message, exception);
     }

     public static void error(String message) {
         _logger.error(newLine);
         _logger.error(message);
     }

     public static void error(String message, Throwable exception) {
         _logger.error(newLine);
         _logger.error(message, exception);
     }

 }

LoggerHelper

创建Global.java文件：

 package helper;

 import java.io.File;

 import javax.servlet.ServletContext;
 import javax.servlet.ServletContextEvent;
 import javax.servlet.ServletContextListener;

 import org.apache.log4j.Logger;
 import org.apache.log4j.PropertyConfigurator;

 public class Global implements ServletContextListener {

     private Logger _logger = Logger.getLogger(Global.class);

     @Override
     public void contextDestroyed(ServletContextEvent arg0) {
         // TODO Auto-generated method stub
         LoggerHelper.info(_logger, "网站停止");
     }

     @Override
     public void contextInitialized(ServletContextEvent arg0) {
         // TODO Auto-generated method stub
         ServletContext sc = arg0.getServletContext();

         String prefix = sc.getRealPath("/WEB-INF");
         String file = "log4j.properties";
         String configPath = prefix + File.separator + file;

         String logFilePath = sc.getRealPath("/");
         System.setProperty("tomcat", logFilePath);

         PropertyConfigurator.configure(configPath);

         LoggerHelper.info(_logger, "网站启动");
     }
 }

Global

web.xml的配置很简单啦，网上搜一下就一大堆了。

 <?xml version="1.0" encoding="UTF-8"?>
 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="http://java.sun.com/xml/ns/javaee"
     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
     id="WebApp_ID" version="3.0">
     <display-name>JspLog4j</display-name>
     <listener>
         <listener-class>helper.Global</listener-class>
     </listener>
     <welcome-file-list>
         <welcome-file>index.jsp</welcome-file>
     </welcome-file-list>
     <error-page>
         <error-code>500</error-code>
         <location>/error.jsp</location>
     </error-page>
 </web-app>

web.xml

自定义错误页面error.jsp。

 <%@page import="com.wyp.helper.LoggerHelper"%>
 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8" isErrorPage="true"%>
 <%
     response.setStatus(200);
     String newLine = System.getProperty("line.separator");
     StringBuilder sb = new StringBuilder();
     sb.append(newLine);
     sb.append("访问的路径：");
     sb.append(newLine);
     sb.append(request.getRequestURI());
     sb.append(newLine);
     sb.append("异常信息：");
     sb.append(newLine);
     sb.append(exception.getClass() + " : " + exception.getMessage());

     Map<String,String[]> map = request.getParameterMap();
     if (map.size()>0) {
         sb.append(newLine);
         sb.append("请求参数：");
         sb.append(newLine);
         for(Map.Entry<String,String[]> entry : map.entrySet()){
             String key = entry.getKey();
             String[] values = entry.getValue();
             sb.append(key+"=");
             for(String value : values){
                 sb.append(value+",");
             }
         }
         sb.append(newLine);
     }
     LoggerHelper.error(sb.toString(),exception);

 %>
 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 <html>
   <head>
     <title>自定义错误页面</title>
   </head>
   <body>
     <h1>自定义错误页面</h1>
   </body>
 </html>

error.jsp

在WEB-INF文件夹里创建log4j.properties文件

 log4j.rootLogger=debug,stdout,logfile

 log4j.appender.stdout=org.apache.log4j.ConsoleAppender
 log4j.appender.stdout.Target=System.err
 log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout

 log4j.appender.logfile=org.apache.log4j.DailyRollingFileAppender
 log4j.appender.logfile.File=${tomcat}/logs/website.txt
 log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
 log4j.appender.logfile.DatePattern='.'yyyy-MM-dd
 log4j.appender.logfile.layout.ConversionPattern=%n%d{yyyy-MM-dd HH\:mm\:ss} %F %m

log4j.properties

默认日志文件存放在：apache-tomcat-6.0.36\bin\下面，可以使用占位符变量表示你日志信息存放的目录，例如：${tomcat}。

使用System.setProperty("tomcat",sc.getRealPath("/"));设置最终的目录。

最后如果部属目录没有log4j.properties和log4j.jar文件，需要手动将这个log4j.properties文件复制到Tomcat\webapps\项目名\WEB-INF文件夹里，将log4j.jar文件复制到对应的Tomcat\webapps\项目名\WEB-INF\lib目录下面。