java web基础 --- URL重定向Filter

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

package com.web1.util;

import java.io.IOException;

import javax.print.attribute.standard.ReferenceUriSchemesSupported;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet Filter implementation class URLOverWriteFilter
 */
@WebFilter("/URLOverWriteFilter")
public class URLOverWriteFilter implements Filter {

    private FilterConfig config;
    /**
     * Default constructor. 
     */
    public URLOverWriteFilter() {
        // TODO Auto-generated constructor stub
    }

    /**
     * @see Filter#destroy()
     */
    public void destroy() {
        // TODO Auto-generated method stub
    }

    /**
     * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
     */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        //do something
        String uri = "";
        HttpServletRequest httpRequest = null;
        if (request instanceof HttpServletRequest) {
            httpRequest = (HttpServletRequest)request;
            System.out.println("URL:" + httpRequest.getRequestURL().toString());
            System.out.println("URI:" + httpRequest.getRequestURI().toString());
            uri = httpRequest.getRequestURI();
            uri = uri.replace("home.html", "helloWorld");
        }
        if (httpRequest.getRequestURI().indexOf("home.html") >= 0) {
            /*if (response instanceof HttpServletResponse) {
                HttpServletResponse httpResponse = (HttpServletResponse)response;
                httpResponse.sendRedirect(uri);
            }*/
            httpRequest.getRequestDispatcher("/helloWorld").forward(httpRequest, response);
        }
        else{
            //go to next Filter
            chain.doFilter(request, response);
        }
    }

    /**
     * @see Filter#init(FilterConfig)
     */
    public void init(FilterConfig fConfig) throws ServletException {
        this.config = fConfig;
    }

}

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>