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Ajax Servlet实例在网络编程的应用

Ajax异步请求,servlet产生随机数据,Html页面无刷新显示。

运行环境：jdk1.5+tomcat 5.5

一、ajaxServlet.java

package com;  
import java.io.IOException;  
import java.io.PrintWriter;  
import javax.servlet.ServletException;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
import java.util.Random;  
public class ajaxServlet extends HttpServlet{  
private static final String CONTENT_TYPE="text/xml; charset=gb2312";  
public void init() throws ServletException{}  
public void doGet(HttpServletRequest request,HttpServletResponse response)  
throws ServletException,IOException{  
 response.setContentType(CONTENT_TYPE);  
 response.setHeader("Cache-Control","no-cache");  
 response.setHeader("Pragma","no-cache");  
 response.setDateHeader("Expires",0);   
 PrintWriter out=response.getWriter();  
 String action=request.getParameter("action");  
if(("send").equals(action)){    
  Random random = new Random();  
  String AA=Integer.toString(Math.abs(random.nextInt()));  
  String BB=Integer.toString(Math.abs(random.nextInt()));  
  String CC=Integer.toString(Math.abs(random.nextInt()));  
  String DD=Integer.toString(Math.abs(random.nextInt()));  
  StringBuffer sb=new StringBuffer();  
  sb.append(AA);  sb.append("@@@");  
  sb.append(BB);  sb.append("@@@");  
  sb.append(CC);  sb.append("@@@");  
  sb.append(DD);  
  out.write(sb.toString());  
  out.close();  
  } }}

二、testajax.html

html  
head  
titleAJAX.html/title  
/head  
script type="text/javascript"   
 
function getResult(){  
  var url = "/Tajax/AajaxServlet?action=send";  
  if (window.XMLHttpRequest) {   
    req = new XMLHttpRequest();   
  }else if (window.ActiveXObject){   
    req = new ActiveXObject("Microsoft.XMLHTTP");   
  }   
  if(req){   
     req.open("GET",url, true);   
     req.onreadystatechange = complete;   
     req.send(null);   
  }   
}

/*分析返回的文本文档*/

function complete(){  
  if (req.readyState == 4) {   
    if (req.status == 200) {   
      // alert(req.responseText);   
      var strResult = unescape(req.responseText);  
      var arrResult = strResult.split("@@@");  
      RemoveRow();  //删除以前的数据.  
      num1 = arrResult[0]; //字段num1的值  
      num2 = arrResult[1]; //字段num2的值  
      num3 = arrResult[2];  
      num4 = arrResult[3];  
      row1= tb.insertRow();  
      cell1 = row1.insertCell();  
      cell1.innerText = num1;  
      cell2 = row1.insertCell();  
      cell2.innerText = num2;  
      row2= tb.insertRow();  
      cell3 = row2.insertCell();  
      cell3.innerText = num3;  
      cell4 = row2.insertCell();  
      cell4.innerText = num4;  
    } else {   
      alert('There was a problem with the request.');   
    }   
  }   
}   
 function RemoveRow(){//保留第一行表头,其余数据均删除.  
    var iRows = tb.rows.length;  
    for(var i=0;i iRows-1;i++){  
       tb.deleteRow(1);  
    }  
 }  
 function MyShow(){//2秒自动刷新一次,2秒取得一次数据.  
  timer = window.setInterval("getResult()",2000);  
  }  
 
 
/script   
 
body onload="MyShow()"  
table width="47%" height="23" border="0" cellpadding="1" cellspacing="0" id="tb"  
trtd代码/td  
td价格/td  
/tr  
/table  
 
form  
p输入股票代码:  
input type="text" size="14" name="phone" id="phone"/  
/p  
p你交易的数量:/p  
ptextarea name="order" rows="6" cols="50" id="order"/textarea/p  
pinput type="submit" value="提交" id="submit" //p  
/form  
 
/body

三、web.xml

?xml version="1.0" encoding="ISO-8859-1"?  
 
web-app xmlns="http://java.sun.com/xml/ns/j2ee" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" 
version="2.4"  
 
display-nameWelcome to Tomcat/display-name  
description  
Welcome to Tomcat  
/description  
servlet  
servlet-nameAajaxServlet/servlet-name  
servlet-classcom.ajaxServlet/servlet-class  
/servlet  
servlet-mapping  
servlet-nameAajaxServlet/servlet-name  
url-pattern/AajaxServlet/url-pattern  
/servlet-mapping  
/web-app