SpringMVC framework + client jQuery cross-domain request solution JSONP

One of the problems that you will inevitably encounter when doing web development is cross-domain, which is blocked by the same-origin policy of the browser, and the request cannot be sent at all. Since the Spring version used is 3.2.13, the @CrossOrigin annotation is not yet supported, and the method of adding a Header such as Access-Control-Allow-Origin to the Response is not very effective, so I won’t talk about it, I just said it here The JSONP method solves the cross-domain problem.

Assuming that the fastjson library is used, the following processing is performed in the Controller:

if(null != user){//登录成功
	//放入session
	session.setAttribute(Constants.DEV_USER_SESSION, user);
	//页面跳转（main.jsp）
	JSONPObject jsonpObject = new JSONPObject();
	jsonpObject.setFunction(callback);//callback是控制器从请求中接收的参数
	jsonpObject.addParameter(user);
	return jsonpObject;
}

In fact, the jackson library can also be used. Coincidentally, there is also a JSONPObject class with the same name, but the encapsulation method is a little different.

In addition, some modifications are required in the client JS. The code to initiate the Ajax request is:

<script>
	function login(){
		//...省略一些表单验证代码
		var userName = $("[name=devCode]").val();
		var password = $("[name=devPassword]").val();
			$.ajax({
				type:"POST",//请求类型
				url:"http://txtx44.natappfree.cc/AppInfoSystem/dev/dologin",//请求的url
				data:{"devCode":userName,"devPassword":password},//请求参数
				dataType:"jsonp",//jsonp是为了能跨域请求
				jsonp: "callback", //参数名
				jsonpCallback: "handleData", //参数值：回调函数名
				error:function(res){
					alert("请求失败！"+res.toString());
				}
			});
	}
	//独立的函数，处理返回的jsonp数据
	function handleData(res){
		if(res && res.devCode != ""){
			alert("登录成功！");//省略跳到主页的代码。。。
		}else{
			alert("登录失败！")
		}
	}
</script>

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