Filter过滤器拦截路径配置

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 {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("servlet1...");
    }

    @Override
    protected 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 {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("servlet2...");
    }

    @Override
    protected 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

    
    


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