弹簧启动控制器 - 将多部分和 JSON 上传到 DTO

javascript java spring-boot

2022-08-31 16:49:50

我想将表单中的文件上传到 Spring Boot API 终结点。

UI 是用 React 编写的：

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);
  }

这是 java 端代码：

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

但是我在Java方面得到了这个例外：

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

我应该如何解决此问题？类似的API端点和JavaScript端代码已经工作。

注意

我见过一个解决方案，它建议请求正文应该有2个属性：一个是JSON部分，另一个是图像。我想看看是否有可能将其自动转换为DTO。

更新 1

客户端发送的上载负载应转换为以下 DTO：

public class ExpensePostDto extends ExpenseBaseDto {

    private MultipartFile image;

    private String description;

    private List<Long> sharers;

}

所以你可以说它是JSON和多部分的混合体。

溶液

该问题的解决方案是在前端和后端使用：FormDataModelAttribute

@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，摆脱它应该由浏览器本身决定，并使用（标准JavaScript）。这应该可以解决问题。Content-TypeFormData

答案 1

是的，你可以简单地通过包装类来做到这一点。

1）创建一个保存表单数据：Class

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

2）创建用于提交数据的 HTML：form

<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>

3）创建一个接收表单数据和文件的方法：textmultipart

@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);
}

4）保存方法：file

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);
    }
}

答案 2

我使用纯JS和Spring Boot创建了类似的东西。这是存储库。我将对象作为请求的一部分发送。UserJSONFilemultipart/form-data

相关摘要如下

代码Controller

@RestController
public class FileUploadController {

    @RequestMapping(value = "/upload", method = RequestMethod.POST, consumes = { "multipart/form-data" })
    public void upload(@RequestPart("user") @Valid User user,
            @RequestPart("file") @Valid @NotNull @NotBlank MultipartFile file) {
            System.out.println(user);
            System.out.println("Uploaded File: ");
            System.out.println("Name : " + file.getName());
            System.out.println("Type : " + file.getContentType());
            System.out.println("Name : " + file.getOriginalFilename());
            System.out.println("Size : " + file.getSize());
    }

    static class User {
        @NotNull
        String firstName;
        @NotNull
        String lastName;

        public String getFirstName() {
            return firstName;
        }

        public void setFirstName(String firstName) {
            this.firstName = firstName;
        }

        public String getLastName() {
            return lastName;
        }

        public void setLastName(String lastName) {
            this.lastName = lastName;
        }

        @Override
        public String toString() {
            return "User [firstName=" + firstName + ", lastName=" + lastName + "]";
        }

    }
}

和代码HTMLJS

<html>    
<head>
    <script>
        function onSubmit() {

            var formData = new FormData();

            formData.append("file", document.forms["userForm"].file.files[0]);
            formData.append('user', new Blob([JSON.stringify({
                "firstName": document.getElementById("firstName").value,
                "lastName": document.getElementById("lastName").value
            })], {
                    type: "application/json"
                }));
            var boundary = Math.random().toString().substr(2);
            fetch('/upload', {
                method: 'post',
                body: formData
            }).then(function (response) {
                if (response.status !== 200) {
                    alert("There was an error!");
                } else {
                    alert("Request successful");
                }
            }).catch(function (err) {
                alert("There was an error!");
            });;
        }
    </script>
</head>

<body>
    <form name="userForm">
        <label> File : </label>
        <br/>
        <input name="file" type="file">
        <br/>
        <label> First Name : </label>
        <br/>
        <input id="firstName" name="firstName" />
        <br/>
        <label> Last Name : </label>
        <br/>
        <input id="lastName" name="lastName" />
        <br/>
        <input type="button" value="Submit" id="submit" onclick="onSubmit(); return false;" />
    </form>
</body>    
</html>