Filter对象的部署与运行

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1.新建一个Dynamic Web Project项目，里面新建一个jsp文件和一个filter文件，整体的框架如下图所示：

2.one.jsp里面的代码如下所示：

<%@page import="java.util.Date"%><%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>example</title></head><body><h2>该页面每隔3秒刷新一次</h2><p>现在的秒钟时间是：<%Date d = new Date();out.print("" + d.getSeconds());response.setHeader("refresh", "3");%></p></body></html>

3.FirstFiler.java里面的代码如下所示：

package filter;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;public class FirstFilter implements Filter {public void destroy() {}public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {response.setContentType("text/html;charset=utf-8");PrintWriter out = response.getWriter();out.print("首先执行过滤器<br>");chain.doFilter(request, response);}@Overridepublic void init(FilterConfig arg0) throws ServletException {}}

4.web.xml文件里面的代码如下所示：

<?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>Servlet</display-name><welcome-file-list><welcome-file>index.html</welcome-file><welcome-file>index.htm</welcome-file><welcome-file>index.jsp</welcome-file><welcome-file>default.html</welcome-file><welcome-file>default.htm</welcome-file><welcome-file>default.jsp</welcome-file></welcome-file-list><filter><filter-name>firstFilter</filter-name><filter-class>filter.FirstFilter</filter-class></filter><filter-mapping><filter-name>firstFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping></web-app>

5.在浏览器里面输入http://localhost:8080/Servlet/one.jsp运行之后得到的结果如下所示：

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