在Filter中拦截路径配置有四种形式
具体资源路径拦截：@WebFilter("/index.jsp") //这是指访问index.jsp的时候会经过过滤器
具体目录拦截：@WebFilter("/user/*") //这是指访问user目录下的所有资源时会经过过滤器
具体后缀名拦截：@WebFilter("*.jsp") //这时指访问后缀名为.jsp的资源时会经过过滤器
所有资源拦截：@WebFilter("/*") //这是指访问所有资源的时候都会经过过滤器
首先演示第一种，具体资源路径拦截，如果访问的不是index.jsp，则不会执行过滤器
package com.zhiying.filter;import javax.servlet.*;import javax.servlet.annotation.WebFilter;import java.io.IOException;@WebFilter("/index.jsp")public class FilterDemo4 implements Filter {public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {System.out.println("执行了过滤器");chain.doFilter(request,response);}}
下面是我访问了hello.jsp，就没有执行过滤器
第二种是具体目录拦截，这里演示，是通过两个servlet例子，我们去访问servlet，具体演示如下，首先我们写两个servlet
package com.zhiying.servlet;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;@WebServlet("/user/a1")public class ServletDemo1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {System.out.println("servlet1...");}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doGet(req, resp);}}
package com.zhiying.servlet;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;@WebServlet("/user/a2")public class ServletDemo2 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {System.out.println("servlet2...");}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doGet(req, resp);}}
然后修改我们的Filter
package com.zhiying.filter;import javax.servlet.*;import javax.servlet.annotation.WebFilter;import java.io.IOException;@WebFilter("/user/*")//@WebFilter("/index.jsp")public class FilterDemo4 implements Filter {public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {System.out.println("执行了过滤器");chain.doFilter(request,response);}}
当我们访问/user/a1和a2的时候，发现过滤器被执行了，而我们访问index.jsp的时候过滤器没有别执行
第三种是后缀名拦截，就是所有该后缀名的资源都会执行过滤器，这里为了演示，我又创建了一个html文件，这里给出html文件和修改该过的Java类
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Title</title></head><body>html...</body></html>
package com.zhiying.filter;import javax.servlet.*;import javax.servlet.annotation.WebFilter;import java.io.IOException;@WebFilter("*.jsp")// @WebFilter("/user/*")// @WebFilter("/index.jsp")public class FilterDemo4 implements Filter {public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {System.out.println("执行了过滤器");chain.doFilter(request,response);}}
从下图可以看出，我们的jsp文件都会被经过过滤器
下面是访问html资源，我们会发现，没有经过过滤器，空空如也
最后一种就是拦截所有资源，仍然给出Java类
package com.zhiying.filter;import javax.servlet.*;import javax.servlet.annotation.WebFilter;import java.io.IOException;@WebFilter("/*")// @WebFilter("*.jsp")// @WebFilter("/user/*")// @WebFilter("/index.jsp")public class FilterDemo4 implements Filter {public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {System.out.println("执行了过滤器");chain.doFilter(request,response);}}
不管是执行index.jsp还是hello.jsp还是html资源，都会经过过滤器
