java网络编程－Ajax+servlet实例

    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 RemoveR
ow(){//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"
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

运行图：