java web基础 --- URL重定向Filter

Posted 2020-08-27 jeremy1888

java web基础 --- URL重定向Filter

httpRequest.getRequestDispatcher("/helloWorld").forward(httpRequest, response);

服务器端转发，不改变浏览器端URL地址，常用

httpResponse.sendRedirect(uri);

浏览器端重定向，改变URL在浏览器地址栏

URLOverWriteFilter.java

 1 package com.web1.util;
 2 
 3 import java.io.IOException;
 4 
 5 import javax.print.attribute.standard.ReferenceUriSchemesSupported;
 6 import javax.servlet.Filter;
 7 import javax.servlet.FilterChain;
 8 import javax.servlet.FilterConfig;
 9 import javax.servlet.ServletException;
10 import javax.servlet.ServletRequest;
11 import javax.servlet.ServletResponse;
12 import javax.servlet.annotation.WebFilter;
13 import javax.servlet.http.HttpServletRequest;
14 import javax.servlet.http.HttpServletResponse;
15 
16 /**
17  * Servlet Filter implementation class URLOverWriteFilter
18  */
19 @WebFilter("/URLOverWriteFilter")
20 public class URLOverWriteFilter implements Filter {
21 
22     private FilterConfig config;
23     /**
24      * Default constructor. 
25      */
26     public URLOverWriteFilter() {
27         // TODO Auto-generated constructor stub
28     }
29 
30     /**
31      * @see Filter#destroy()
32      */
33     public void destroy() {
34         // TODO Auto-generated method stub
35     }
36 
37     /**
38      * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
39      */
40     public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
41         //do something
42         String uri = "";
43         HttpServletRequest httpRequest = null;
44         if (request instanceof HttpServletRequest) {
45             httpRequest = (HttpServletRequest)request;
46             System.out.println("URL:" + httpRequest.getRequestURL().toString());
47             System.out.println("URI:" + httpRequest.getRequestURI().toString());
48             uri = httpRequest.getRequestURI();
49             uri = uri.replace("home.html", "helloWorld");
50         }
51         if (httpRequest.getRequestURI().indexOf("home.html") >= 0) {
52             /*if (response instanceof HttpServletResponse) {
53                 HttpServletResponse httpResponse = (HttpServletResponse)response;
54                 httpResponse.sendRedirect(uri);
55             }*/
56             httpRequest.getRequestDispatcher("/helloWorld").forward(httpRequest, response);
57         }
58         else{
59             //go to next Filter
60             chain.doFilter(request, response);
61         }
62     }
63 
64     /**
65      * @see Filter#init(FilterConfig)
66      */
67     public void init(FilterConfig fConfig) throws ServletException {
68         this.config = fConfig;
69     }
70 
71 }

 

web.xml

按照filter-mapping的顺序

<?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" metadata-complete="true" version="3.0">
  <description>
         Hello World Servlet
    </description>
  <display-name>Hello World Servlet</display-name>
  <filter>
    <filter-name>Encode Filter</filter-name>
    <filter-class>com.web1.util.RequestEncodeFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>Encode Filter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <filter>
    <filter-name>URLOverFilter Filter</filter-name>
    <filter-class>com.web1.util.URLOverWriteFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>URLOverFilter Filter</filter-name>
    <url-pattern>/home.html</url-pattern>
  </filter-mapping>
  
  <servlet>
    <servlet-name>helloWorld</servlet-name>
    <servlet-class>com.web1.hello.HelloWorldServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>helloWorld</servlet-name>
    <url-pattern>/helloWorld</url-pattern>
  </servlet-mapping>
  <servlet>
    <servlet-name>helloImage</servlet-name>
    <servlet-class>com.web1.hello.ImageServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>helloImage</servlet-name>
    <url-pattern>/helloImage</url-pattern>
  </servlet-mapping>
</web-app>