@WebServlet("/ajax.do")
public class HelloAjax extends HttpServlet {
private static final long serialVersionUID = 1L;
public HelloAjax() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().write("Ajax Test");
}
}<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
window.onload=init;
function init(){
var btn=document.getElementById("btn");
btn.onclick=getdata;
}
function getdata(){
var xhr;
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xhr=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xhr=new ActiveXObject("Microsoft.XMLHTTP");
}
xhr.onreadystatechange=function(){
if(xtr.readyState==4&&xtr.status==200){
document.getElementById("display").innerHTML=xhr.responseText;
}
}
xhr.open("get","ajax.do",true);
xhr.send();
}
</script>
</head>
<body>
<input type="button" id="btn" value="测试">
<div id="display"></div>
</body>
</html>注意:(1).ajax可以实现不加载整个页面的情况下，对页面某部分进行更新
如何使用ajax：
1.创建XMLHttpRequest对象
2.检测XMLHttpRequest状态，在合适的时候进行处理
3.发送请求