html页面代码（使用了jquery）：
- <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
- <html xmlns="http://www.w3.org/1999/xhtml">
- <head>
- <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
- <script type="text/javascript" src="js/jquery-1.2.6.js"></script>
- <script type="text/javascript">
- //定义一个全局的XmlHttpRequest类型的变量
- var xmlHttp = false;
- //创造一个XmlHttpRequest对象
- function createXmlHttpRequest() {
- /* Create a new XMLHttpRequest object to talk to the Web server */
- /*@cc_on @*/
- /*@if (@_jscript_version >= 5)
- try {
- xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
- } catch (e) {
- try {
- xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
- } catch (e2) {
- xmlHttp = false;
- }
- }
- @end @*/
- if (!xmlHttp && typeof XMLHttpRequest != 'undefined') {
- xmlHttp = new XMLHttpRequest();
- }
- }
- //发送异步请求
- function callServer() {
- createXmlHttpRequest();
- var str = $("#t1").val();
- var url = "test1.do";
- // Open a connection to the server
- xmlHttp.open("POST", url, true);
- // Setup a function for the server to run when it's done
- xmlHttp.onreadystatechange = updatePage;
- //使用post方法提交是，这句非常重要，否则servlet无法接收参数
- xmlHttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
- // Send the request
- var param = "a=" + str;
- xmlHttp.send(param);
- }
- //回调函数，对页面内容进行更新
- function updatePage() {
- if (xmlHttp.readyState == 4) {
- var response = xmlHttp.responseText;
- $("#t1").val(response);
- $("#done").append(response);
- }
- }
- </script>
- <title>AJAX测试</title>
- </head>
- <body>
- <form id="form1" name="form1" method="post" action="">
- <input type="text" name="t1" id="t1" />
- <input type="button" name="b1" id="b1" value="提交" onclick="callServer()" />
- <div id="done"></div>
- </form>
- </body>
- </html>
服务器端的servlet代码：
- package andycpp;
- 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 Controller extends HttpServlet {
- @Override
- protected void doPost(HttpServletRequest req, HttpServletResponse resp)
- throws ServletException, IOException {
- String s = req.getParameter("a");
- resp.setContentType("text/xml");
- resp.setHeader("Cache-Control", "no-cache");
- resp.getWriter().write(s);
- }
- }