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>
<title>AJAX.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);}
<body onload="MyShow()">
<table width="47%" height="23" border="0" cellpadding="1" cellspacing="0" id="tb">
<tr><td>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>
<p><textarea name="order" rows="6" cols="50" id="order"></textarea></p>
<p><input 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-name>Welcome to Tomcat</display-name>
<description>
Welcome to Tomcat
</description>
<servlet>
<servlet-name>AajaxServlet</servlet-name>
<servlet-class>com.ajaxServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>AajaxServlet</servlet-name>
<url-pattern>/AajaxServlet</url-pattern>
</servlet-mapping>
</web-app>
运行图：
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