通过Ajax进行POST提交JSON类型的数据到SpringMVC Controller的方法

现在在做的项目用到了SpringMVC框架，需要从前端angular接收请求的JSON数据，为了测试方便，所以直接先用AJAX进行测试，不过刚开始用平时用的ajax方法，提交请求会出现415或者400错误，经过研究，终于可以了，现在做个总结。

js代码：

function postSimpleData() {
        $.ajax({
            type: "POST",
            url: "Service/SimpleData",
            contentType: "application/json", //必须有
            dataType: "json", //表示返回值类型，不必须
            data: JSON.stringify({ "foo": "foovalue", "bar": "barvalue" }),  //相当于 //data: "{"str1":"foovalue", "str2":"barvalue"}",
            success: function (jsonResult) {
                alert(jsonResult);
            }
        });
    }
    function login(){
	$.ajax({
	    url: "Service/login",
	    type: "POST",
	    contentType: "application/json",
	    dataType: "json",
	    data: JSON.stringify({
	    	MachineIP:"127.0.0.1",
	    	AppTag:"4",
	    	RequestInfo:{
	    		StaffCode:"",
	    		Password:"",
	    		StaffCard:"01411"
	    	},
	    }),
	    async: true,
	    success: function(data) {
	    	var ss = JSON.stringify(data);
	    	$("#result").val(ss);
	        console.log(ss);
	    }
	});
    }
    function postEmployees() {
        $.ajax({
            type: "POST",
            url: "Service/Employees",
            contentType: "application/json",
            dataType: "json",
            data: JSON.stringify({                "Employees": [
                                    { "firstName": "Bill", "lastName": "Gates" },
                                    { "firstName": "George", "lastName": "Bush" },
                                    { "firstName": "Thomas", "lastName": "Carter" }
                                 ]

            }),
            success: function (jsonResult) {
                alert(jsonResult);
            }
        });
    }

JAVA Controller代码：

@RequestMapping(value = "/SimpleData", method = RequestMethod.POST)
    @ResponseBody
    public ActionResult SimpleData(string foo, string bar) {
        return Json("SimpleData", JsonRequestBehavior.AllowGet);
    }

    @RequestMapping(value = "/login", method = RequestMethod.POST)
    @ResponseBody
    public ResponseProtocolMap login(@RequestBody JSONObject requestJson, HttpServletRequest request) {
        ResponseProtocolMap responseProtocolMap = null;
        String machineIP = RequestJsonUtils.getMachineIP(requestJson);
        String appTag = RequestJsonUtils.getAppTag(requestJson);
        JSONObject requestInfo = RequestJsonUtils.getRequestInfo(requestJson);
        if (requestInfo == null) {
            responseProtocolMap = new ResponseProtocolMap("-1", "参数错误");
        } else {
            String staffCode = RequestJsonUtils.getValueByKey(requestInfo, "StaffCode");
            String password = RequestJsonUtils.getValueByKey(requestInfo, "Password");
            String staffCard = RequestJsonUtils.getValueByKey(requestInfo, "StaffCard");
            responseProtocolMap = sysLoginService.login(staffCode, password, staffCard, appTag, request);
        }
        return responseProtocolMap;
    }

    @RequestMapping(value = "/Employees", method = RequestMethod.POST)
    @ResponseBody
    public ActionResult Employees(List<Employee> Employees) {
        return Json("Employees", JsonRequestBehavior.AllowGet);
    }

public class Employee{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

值得注意的有2点：

1）Ajax 选项中

contentType: "application/json"

 这一条必须写，表明request的数据类型是json。

而

dataType: "json"

这一条表示返回值的类型，不是必须的，且依据返回值类型而定。

2）选项中

data: JSON.stringify({ "foo": "foovalue", "bar": "barvalue" })

 很多时候我们将数据写作：

{ "foo": "foovalue", "bar": "barvalue" }

这样会导致错误，因为js会默认将这个json对象放到表单数据中，故而导致controller接收不到。

有两种办法处理：第一种方式是用JSON.stringify()函数，其中JSON被Ecmascript5定义为全局对象。

第二种方式是直接用双引号包裹起来，比如data: "{"str1":"foovalue", "str2":"barvalue"}"。