ajax数据请求

利用XMLHTTPRequest进行异步数据请求

前台代码：

function createXMLHttpRequest(){
	var xmlrequest;
	if(window.XMLHttpRequest){
		xmlrequest=new XMLHttpRequest();
	}else if(window.ActiveXObject){
		try{
			xmlrequest=new ActiveXObject("Msxm12.XMLHTTP");
		}catch(e){
			try{
				xmlrequest=new ActiveXObject("Microsoft.XMLHTTP");
			}catch(e){
				xmlrequest="";
			}
		}
	}
	return xmlrequest;
}

function change(){
	var xmlrequest=createXMLHttpRequest();
	xmlrequest.open("POST","TestServlet",true);
	xmlrequest.onreadystatechange=function(){
		if(xmlrequest.readyState==4&&xmlrequest.status==200){
			var data=JSON.parse(xmlrequest.responseText);
			var content="<table border=1>";
			for(var i=0;i<data.length;i++){
				content+="<tr>";
				for(o in data[i]){
					content+="<td>"+data[i][o]+"</td>";
				}
				content+="</tr>";
			}
			content+="</table>";
			document.getElementById("test").innerHTML=content;
		}
	};
	xmlrequest.send();
}

后台代码：TestServlet.java

public void doPost(HttpServletRequest request,HttpServletResponse response)
			throws servletexception,IOException {

		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
	        String data="[{\"name\":\"apple\",\"price\":23},{\"name\":\"banana\",\"price\":12},{\"name\":\"orange\",\"price\":8}]";
		out.write(data);
		out.flush();
		out.close();
	}