xingzhe

虽然java ee 自带了log组件，在程序中可以直接调用，但是它还不能满足我们开发中的一些要求，例如将log信息输出到文件，输出到emal，输出到socket
而这些log4j实现了

下面以一个filter为例说明如何将在web应用中将有关的信息输出到console和文件中。
1.准备一个sort1.properties文件，并进行配置,并存放在webRoot目录下
log4j.rootLogger=INFO,A1,R
log4j.appender.A1=org.apache.log4j.ConsoleAppender
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss} %5p [%c{1}] - %m%n

log4j.appender.R=org.apache.log4j.DailyRollingFileAppender
log4j.appender.R.File=d:/test.log
log4j.appender.R.DatePattern='.'yyyy-MM-dd
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss} %5p [%c] - %m%n

2.在web.xml配置filter
<filter>
  <filter-name>logFilter</filter-name>
  <filter-class>com.sunhm.LogFilter</filter-class>
  <init-param>
   <param-name>log4j-init-file</param-name>
   <param-value>sort1.properties</param-value>
  </init-param>
 </filter>
 <filter-mapping>
  <filter-name>logFilter</filter-name>
  <url-pattern>/*</url-pattern>
 </filter-mapping>

3.在buildPath中添加common log4j组件

3.在程序中实现Filter接口
package com.sunhm;

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;

public class LogFilter implements Filter {

 static Logger logger = Logger.getLogger(LogFilter.class);

 
 public void destroy() {
  // TODO Auto-generated method stubl
  logger.info("LogFilter::destroy");
  

 }

 public void doFilter(ServletRequest arg0, ServletResponse arg1,
   FilterChain arg2) throws IOException, ServletException {
  // TODO Auto-generated method stub

  HttpServletRequest request = (HttpServletRequest) arg0;
  HttpServletResponse response = (HttpServletResponse) arg1;

  long startTime = System.currentTimeMillis();
  String requestURI = request.getRequestURI();

  requestURI = request.getQueryString() == null ? requestURI
    : (requestURI + "?" + request.getQueryString());

  arg2.doFilter(request, response);

  long endTime = System.currentTimeMillis();

  logger.info(request.getRemoteAddr() + " 访问了 " + requestURI + ", 总用时 "
    + (endTime - startTime) + " 毫秒。");

 }

 public void init(FilterConfig arg0) throws ServletException {
  // TODO Auto-generated method stub

  // 获取 Filter 的 name，配置在 web.xml 中  
  String prefix = arg0.getServletContext().getRealPath("/");
  String file = arg0.getInitParameter("log4j-init-file");
  if(file != null)
  {
   PropertyConfigurator.configure(prefix+ file);
  }  

  logger.info("LogFilter:init");
 }

}