前端：templete中

<input type="file" value="" id="file" @change="uploadTest">

script中

methods: {
    uploadTest (e) {
      let formData = new FormData()
      let data = JSON.stringify({
        aa: 'xxx',
        bb: 123
      })
      formData.append('file', e.target.files[0])
      formData.append('data', new Blob([data], {type: 'application/json'})) // 同时上传文件和JSON,这里1.用动new Blob;2[data]中括号;3.必须加type,postman见本站https://blog.csdn.net/FRESHET/article/details/121286971

      //   后台测试地址
      let url = 'http://192.168.1.103:8081/upload'
      let config = {
        headers: {'Content-Type': 'multipart/form-data'}
      }
      this.$axios.post(url, formData, config).then(function (response) {
        console.log(response.data)
      })
    }
  }

后台代码：

@CrossOrigin
    @PostMapping("/upload")
    @ResponseBody
    public String upload(@RequestPart("file") MultipartFile file,@RequestPart Map<String,Object> data ) {
        if (file.isEmpty()) {
            return "上传失败，请选择文件";
        }

        String fileName = file.getOriginalFilename();
        String filePath = "E:\\vuetest\\vue_upload\\";
        File dest = new File(filePath + fileName);
        try {
            file.transferTo(dest);
            System.out.println(data.get("aa"));
            System.out.println(data.get("bb"));
            System.out.println("upload ok");
            return "上传成功";
        } catch (IOException e) {
            System.err.println(e.toString());
        }
        return "上传失败！";
    }

效果：

xxx
123
upload ok