解决XMLHttpRequest请求的缓存问题

来源：互联网发布：化妆品销售数据编辑：程序博客网时间：2024/06/03 21:39

什么是缓存,就不用解释了, 大家在更新CSDN博客时经常遇到的问题,很头疼. 如何解决浏览器的缓存问题,看例子.

一个访问页面计数器的小例子.不多做解释,直接运行,看运行效果.

AJAXNew.html中:

<html>    <head>        <title></title>        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">        <script type="text/javascript">           var cachexmlhttp;              function cache(){               //创建XMLHttpRequest对象               if(window.XMLHttpRequest){                   //IE7、IE8、FireFox、Mozilla、Safari、Opera                   cachexmlhttp= new XMLHttpRequest();                   if(cachexmlhttp.overrideMimeType){                       cachexmlhttp.overrideMimeType("text/xml");                   }               }else if(window.ActiveXObject){                   //IE6,IE5.5,IE5                   var activexName=["MSXML2.XMLHTTP.60","MSXML2.XMLHTTP.5.0",                       "MSXML2.XMLHTTP.4.0","MSXML2.XMLHTTP.3.0","MSXML2.XMLHTTP",                        "Miscrosoft.XMLHTTP"];                    for(var i=0;i<activexName.length;i++){                        try{                            cachexmlhttp=new ActiveXObject(activexName[i]);                            break;                        }catch(e){                                                    }                                        }                               }                if(cachexmlhttp===undefined || cachexmlhttp===null){                   alert("当前浏览器不支持创建XMLHttpRequest对象，请更换浏览器");                   return;               }               //2,注册回调方法               cachexmlhttp.onreadystatechange=function(){                   if(cachexmlhttp.readyState===4){                       if(cachexmlhttp.status===200){                           var message=cachexmlhttp.responseText;                           var div=document.getElementById("cachemessage");                           div.innerHTML=message;                       }                   }               };                             //3,设置和服务器端交互的相应参数——Get方式               cachexmlhttp.open("GET","Cache",true);                              //4,设置向服务器端发送的数据，启动和服务器端的交互               cachexmlhttp.send(null);           }                   </script>         </head>    <body>        <div id="message"></div>        <br/>      <input type="button" onclick="cache();" value="测试缓存问题"/>            <div id="cachemessage"></div>    </body></html>

Cache.java(一个Servlet)中：

import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * * @author xuemin */@WebServlet(urlPatterns = {"/Cache"})public class Cache extends HttpServlet {    protected void processRequest(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("text/html;charset=UTF-8");        PrintWriter out = response.getWriter();        try {           Integer counter = (Integer)request.getSession().getAttribute("Counter");             if(counter ==null){                 counter = 0;             }else{                counter++;             }             request.getSession().setAttribute("Counter",counter);             out.println("当前计数器的值为:"+counter);        } finally {                        out.close();        }    }

运行以上程序, 很明显存在缓存问题,如何解决?

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