Ajax

public class Ajax01 extends HttpServlet{
	@Override
	protected void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		PrintWriter out = response.getWriter();
		JSONObject jo = new JSONObject();
		jo.put("mingzi", "chenchunqiu");
		jo.put("age", 33);
		out.print(jo);
		out.close();
	}
}

function loadInfo(){
		//步骤1.获取xml对象
		var xhr ;//new XMLHttpRequest();
		if(window.XMLHttpRequest){
			xhr = new XMLHttpRequest();
		}else{
			xhr=new ActiveXObject("Microsoft.XMLHTTP");
		}
		//发送请求
		xhr.open("get", "getAjax01", true);
		
		xhr.onreadystatechange=function(){
			if(xhr.readyState==4){
				alert(xhr.responseText);//xhr.responseText()获取的是json字符串
				//JSON.stringify(jsonobj); //可以将json对象转换成json对符串 
				var jsonObj = eval(‘(‘ + xhr.responseText + ‘)‘);//可以将json字符串转换成json对象,注意需要在json字符外包裹一对小括号
				alert("姓名："+jsonObj.mingzi);
				alert("年龄："+jsonObj.age);		
		}
		}
		
		xhr.send(null);
	}