axios发送post请求springMVC接收不到参数的解决方法

//设置全局的
axios.defaults.headers.post['Content-Type'] = 'application/x--form-urlencoded';
var instance = axios.create({}) // 这样创建出来的 只需要
instance.defaults.headers.post['Content-Type'] = 'application/x--form-urlencoded';

var params = new URLSearchParams();
params.append("username", _this.username);
params.append("password", _this.password);
axios.post("/service/login", paramsOfJson
   ).then(function (response) {
    console.log(response);
   }).catch(function (error) {
    console.log(error);
   })

@PostMapping(value = "/login")
public String testLogin(@RequestBody Map dataMap)