这是ajax原生态的写法，并没有jquery进行封装：
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-1.8.3.min.js"></script>
<script type="text/javascript">
$(function(){
$("#ajax").click(function(){
//创建xhr
var xhr;
if(window.ActiveXObject){//IE
xhr=new ActiveXObject("Microsoft.XMLHTTP");
}else if(window.XMLHttpRequest){//webkit,IE7+
xhr=new XMLHttpRequest();
}
//初始化xhr
xhr.open("get","${pageContext.request.contextPath}/ajax/query");
//发送请求
xhr.send();
//监听响应
xhr.onreadystatechange=function(){
if(xhr.readyState==4 && xhr.status==200){
var ret = xhr.responseText;
//解析json转换为js对象
var users = $.parseJSON(ret);
$("tbody>tr:gt(0)").remove();
for(var i=0;i<users.length;i++){
var id = users[i].id;
var name=users[i].name;
var birthday = users[i].birthday;
//dom显示更新
$("tbody").append(
"<tr>"+
"<td>"+id+"</td>"+
"<td>"+name+"</td>"+
"<td>"+birthday+"</td>"+
"</tr>"
);
};
};
};
});
});
</script>
