html：
<input id="file" type="file" @change="tirggerFile($event)">
js：
export default{
 	data(){
 		return{
       userInfo: '',
       headimgurl: {}
 		}
 	},
 	methods: {
	 	tirggerFile (e) {
	       	this.headimgurl = new FormData(); // 创建一个form类型的数据
	        this.headimgurl.append("headimgurl",e.target.files[0]); // 获取上传文件的数据
	        // 往对象插入数据
            this.headimgurl.append("name",this.userInfo.name);
            this.headimgurl.append("paperwork_type",this.userInfo.paperwork_type);
            this.headimgurl.append("paperwork_num",this.userInfo.paperwork_num);
            this.headimgurl.append("phone",this.userInfo.phone);
            this.headimgurl.append("sex",sex);
            this.headimgurl.append("city",this.userInfo.city);
            this.headimgurl.append("area",this.userInfo.area);
            this.headimgurl.append("school",this.userInfo.school);
            this.headimgurl.append("grade",grade);
            
	           axios.post("User/updateUserInfo",this.headimgurl).then((res)=>{
	            if (res.data.status === 1) {
	              // 清空file的值
	              var file = document.getElementById('file');
	              file.outerHTML = file.outerHTML;
	              // 重新获取数据
	              this.information()
	              alert(res.data.message)
	            } else {
	              alert(res.data.message)
	            }
          })
	    }
 	}
}