今天初学ajax，感觉ajax真是一门好技术，所以就感觉得要学好它
先写一个简单的例子吧
首先创建一个jsp吧，ajax.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'ajax.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<script type="text/javascript">
var xmlHttpRequest = null; //声明一个空对象以接收XMLHttpRequest对象
function ajaxSubmit()
{
if(window.ActiveXObject) // IE浏览器
{
xmlHttpRequest = new ActiveXObject("Microsoft.XMLHTTP");
}
else if(window.XMLHttpRequest) //除IE外的其他浏览器实现
{
xmlHttpRequest = new XMLHttpRequest();
}
if(null != xmlHttpRequest)
{
var v1 = document.getElementById("value1ID").value;
var v2 = document.getElementById("value2ID").value;
xmlHttpRequest.open("POST", "AjaxServlet", true);
//关联好ajax的回调函数
xmlHttpRequest.onreadystatechange = ajaxCallback;
//真正向服务器端发送数据
// 使用post方式提交，必须要加上如下一行
xmlHttpRequest.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
xmlHttpRequest.send("v1=" + v1 + "&v2=" + v2);
}
}
function ajaxCallback()
{
if(xmlHttpRequest.readyState == 4)
{
if(xmlHttpRequest.status == 200)
{
var responseText = xmlHttpRequest.responseText;
document.getElementById("div1").innerHTML = responseText;
}
}
}
</script>
</head>
<body>
<input type="button" value="get content from server" <input type="text" name="value1" id="value1ID"><br>
<input type="text" name="value2" id="value2ID"><br>
<div id="div1"></div>
</body>
</html>然后再创建一个进行异步处理的servlet AjaxServlet.servlet
此servlet处理ajax.jsp 然后返回数据
/**
* author botao
* 功能:用来测试ajax的servlet
*/
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;
public class AjaxServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException
{
System.out.println("doGet invoked");
process(req, resp);
}
private void process(HttpServletRequest req, HttpServletResponse resp)
throws IOException
{
String v1 = req.getParameter("v1");
String v2 = req.getParameter("v2");
System.out.println("v1=" + v1 + ", v2=" + v2);
String v3 = String.valueOf(Integer.valueOf(v1) + Integer.valueOf(v2));
PrintWriter out = resp.getWriter();
// try
// {
// Thread.sleep(5000);
// }
// catch (InterruptedException e)
// {
// e.printStackTrace();
// }
resp.setHeader("pragma", "no-cache");
resp.setHeader("cache-control", "no-cache");
out.println(v3);
out.flush();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException
{
System.out.println("doPost invoked");
this.process(req, resp);
}
}这样，一个简单的ajax异步刷新就完成了
