logfilter

package lee;
 
 import javax.servlet.*;
  import javax.servlet.http.*;
  import javax.servlet.annotation.*;
  
  import java.io.*;
  
  /**
  * Description:
  * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
  * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
  * <br/>This program is protected by copyright laws.
  * <br/>Program Name:
  * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
  * @version  1.0
  */
 @WebFilter(filterName="log"
     ,urlPatterns={"/*"})
 public class LogFilter implements Filter
 {
     // FilterConfig可用于访问Filter的配置信息
     private FilterConfig config;
     // 实现初始化方法
     public void init(FilterConfig config)
     {
         this.config = config;
     }
     // 实现销毁方法
     public void destroy()
     {
         this.config = null;
     }
    // 执行过滤的核心方法
     public void doFilter(ServletRequest request,
         ServletResponse response, FilterChain chain)
         throws IOException,ServletException
     {
         // ---------下面代码用于对用户请求执行预处理---------
         // 获取ServletContext对象，用于记录日志
         ServletContext context = this.config.getServletContext();
         long before = System.currentTimeMillis();
         System.out.println("开始过滤...");
         // 将请求转换成HttpServletRequest请求
         HttpServletRequest hrequest = (HttpServletRequest)request;
         // 输出提示信息
         System.out.println("Filter已经截获到用户的请求的地址： " +
             hrequest.getServletPath());
         // Filter只是链式处理，请求依然放行到目的地址
         chain.doFilter(request, response);
         // ---------下面代码用于对服务器响应执行后处理---------
         long after = System.currentTimeMillis();
         // 输出提示信息
         System.out.println("过滤结束");
        // 输出提示信息
         System.out.println("请求被定位到" + hrequest.getRequestURI() +
             "   所花的时间为: " + (after - before));
     }
 }