通過過濾器實現控制動態資源不要緩存

1。NoCacheFilter.java文件：

package com.itheima.example;

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;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//控制動態資源不要緩存過濾器
public class NoCacheFilter implements Filter {

    public void init(FilterConfig filterConfig) throws ServletException {

    }

    public void doFilter(ServletRequest req, ServletResponse resp,
            FilterChain chain) throws IOException, ServletException {

//      HttpServletRequest request = (HttpServletRequest)req;
//      HttpServletResponse response = (HttpServletResponse)resp;

        HttpServletRequest request = null;
        HttpServletResponse response = null;
        try{
            request  = (HttpServletRequest)req;
            response = (HttpServletResponse)resp;
        }catch(Exception e){
            throw new RuntimeException("not-http request or response");
        }


        response.setHeader("Expires", "-1");
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Pragma", "no-cache");
        chain.doFilter(request, response);
    }

    public void destroy() {

    }

}

2。ServletDemo3.java文件：

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ServletDemo3 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.getWriter().write("中文你隨便輸");
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

3。web.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

  <servlet>
    <servlet-name>ServletDemo3</servlet-name>
    <servlet-class>ServletDemo3</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>ServletDemo3</servlet-name>
    <url-pattern>/servlet/ServletDemo3</url-pattern>
  </servlet-mapping>
<welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
</welcome-file-list>

<filter>
    <filter-name>NoCacheFilter</filter-name>
    <filter-class>com.itheima.example.NoCacheFilter</filter-class>
</filter>
<filter-mapping><!-- 按照此標籤的出現順序 -->
    <filter-name>NoCacheFilter</filter-name>
    <url-pattern>*.jsp</url-pattern>
</filter-mapping>


</web-app>

4。運行：http://localhost:8080/Filter_project/servlet/ServletDemo3
5。結果：
沒有緩存
同時輸出一下內容：中文你隨便輸