Spring Boot控制器-将Multipart和JSON上载到DTO

Question

export function createExpense(formData) {
  return dispatch => {
    axios.post(ENDPOINT,
      formData, 
      headers: {
        'Authorization': //...,
        'Content-Type': 'application/json'
      }
      ).then(({data}) => {
        //...
      })
      .catch(({response}) => {
        //...
      });
    };
}

  _onSubmit = values => {
    let formData = new FormData();
    formData.append('title', values.title);
    formData.append('description', values.description);
    formData.append('amount', values.amount);
    formData.append('image', values.image[0]);
    this.props.createExpense(formData);
  }

@RequestMapping(path = "/{groupId}", method = RequestMethod.POST)
public ExpenseSnippetGetDto create(@RequestBody ExpensePostDto expenseDto, @PathVariable long groupId, Principal principal, BindingResult result) throws IOException {
   //..
}

org.springframework.web.HttpMediaTypeNotSupportedException: Content type 'multipart/form-data;boundary=----WebKitFormBoundaryapHVvBsdZYc6j4Af;charset=UTF-8' not supported

我见过一个解决方案，它建议请求体应该有两个属性：一个是JSON部分下的属性，另一个是图像的属性。我想看看是否有可能将它自动转换为DTO。

客户端发送的上载有效负载应转换为以下DTO：

public class ExpensePostDto extends ExpenseBaseDto {

    private MultipartFile image;

    private String description;

    private List<Long> sharers;

}

所以可以说它是JSON和Multipart的混合体。

@RequestMapping(path = "/{groupId}", method = RequestMethod.POST,
        consumes = {"multipart/form-data"})
public ExpenseSnippetGetDto create(@ModelAttribute ExpensePostDto expenseDto, @PathVariable long groupId, Principal principal) throws IOException {
   //...
}

在前端，去掉content-type，因为它应该由浏览器本身确定，而使用formdata（标准JavaScript）。那应该能解决问题了。

Answer 1

是的，您可以简单地通过包装类来完成。

1）创建类来保存表单数据：

public class FormWrapper {
    private MultipartFile image;
    private String title;
    private String description;
}

2）创建用于提交数据的HTML表单：

<form method="POST" enctype="multipart/form-data" id="fileUploadForm" action="link">
    <input type="text" name="title"/><br/>
    <input type="text" name="description"/><br/><br/>
    <input type="file" name="image"/><br/><br/>
    <input type="submit" value="Submit" id="btnSubmit"/>
</form>

@PostMapping("/api/upload/multi/model")
public ResponseEntity<?> multiUploadFileModel(@ModelAttribute FormWrapper model) {
    try {
        // Save as you want as per requiremens
        saveUploadedFile(model.getImage());
        formRepo.save(mode.getTitle(), model.getDescription());
    } catch (IOException e) {
        return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
    }

    return new ResponseEntity("Successfully uploaded!", HttpStatus.OK);
}

private void saveUploadedFile(MultipartFile file) throws IOException {
    if (!file.isEmpty()) {
        byte[] bytes = file.getBytes();
        Path path = Paths.get(UPLOADED_FOLDER + file.getOriginalFilename());
        Files.write(path, bytes);
    }
}