简介：

实验多个过滤器进行拦截和放行时的运行顺序：

首先创建AServlet：

package demo1; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/AServlet") public class AServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("------Aervlet-----"); } }

然后创建两个过滤器：

AFilter：

package demoFilter; 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; public class AFilter implements Filter { /** * 创建之后立即执行，用来做初始化，Filter在服务器启动时就创建 */
    public void init(FilterConfig filterConfig) throws ServletException { System.out.println("AFilter：过滤器出生！"); } /** * 每次过滤时都会执行 */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { System.out.println("AFilter：拦截成功！"); chain.doFilter(request, response); System.out.println("AFilter：已放行！"); } /** * 销毁之前执行，用来对非内存资源进行释放 */
    public void destroy() { System.out.println("AFilter：过滤器死亡！"); } }

BFilter:

package demoFilter; import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; public class BFilter implements Filter { @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { System.out.println("BFilter：拦截成功！"); chain.doFilter(request, response); // 放行：让资源请求通过
        System.out.println("BFilter：已放行！"); } }

然后在web.xml中配置Filter：

这里AFilter是拦截所有资源，BFilter只拦截AServlet；

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
    <display-name>day0412_1</display-name>
    <filter>
        <filter-name>AFilter</filter-name>    <!-- 自定义名称 -->
        <filter-class>demoFilter.AFilter</filter-class> <!-- Filter类所在路径 -->
    </filter>
    <filter-mapping>
        <filter-name>AFilter</filter-name> <!-- 自定义名称匹配 -->
        <url-pattern>/*</url-pattern> <!-- 拦截的资源路径 -->
    </filter-mapping>
    <filter>
        <filter-name>BFilter</filter-name>    <!-- 自定义名称 -->
        <filter-class>demoFilter.BFilter</filter-class> <!-- Filter类所在路径 -->
    </filter>
    <filter-mapping>
        <filter-name>BFilter</filter-name> <!-- 自定义名称匹配 -->
        <url-pattern>/AServlet</url-pattern> <!-- 拦截的资源路径 -->
    </filter-mapping>
</web-app>

再创建一个jsp资源文件：

<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="ISO-8859-1"%>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>my index.jsp</title>
</head>
<body>
<% System.out.println("This is a apple!!!!!"); %>
<h1>This is a JSP named index.jsp!!</h1>
</body>
</html>