vue-resource 上传图片

const formData = new FormData()
formData.append('file',img,params.name);
formData.append('id',params.id);
formData.append('name',params.name);
return new Promise((resolve,reject)=>{
  Vue.http.post(uploadImg,formData).then(function(res){
    resolve(res.body);
  },function(res,status,request){
    reject(res,status,request);
  });
});