Spring無法處理“多部分/表單數據” POST請求（錯誤400“錯誤請求”）

Question

當我向此服務器代碼發布請求時-一切正常：

@RequestMapping(method = RequestMethod.POST, consumes = { "application/json" })
public ResponseEntity<String> addQuestion(@RequestBody String dtoObject) { ... }

但是，如果我將請求更改為“ multipart / form-data”，則Spring返回錯誤400“ Bad request”：

@RequestMapping(method = RequestMethod.POST, consumes = { "multipart/form-data" })
public ResponseEntity<String> addQuestion(@RequestBody String dtoObject) { ... }

為什么？ 可能我應該創建一些額外的bean？

PS：我需要“ multipart / form-data”與json對象一起發送文件。

Answer 1

我認為您無法將文件反序列化到請求正文中的dtoObject。 您將需要使用@RequestPart來執行此操作。

@RequestMapping(method = RequestMethod.POST, consumes = { "multipart/form-data" })
public ResponseEntity<String> addQuestion2(@RequestPart("question") QuestionPostDto dtoObject, @RequestPart("file") MultiPartFile file)  { ... }

您的請求必須是formdata：要上傳的文件和json格式的文件question.json

這是我郵遞員的有效載荷示例

Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW

------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="file"; filename="QLbLFIR.gif"
Content-Type: image/gif


------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="question"; filename="question.json"
Content-Type: application/json


------WebKitFormBoundary7MA4YWxkTrZu0gW--

或者如果您不想傳遞json格式的文件，則可以使用普通字符串傳遞它

@RequestMapping(method = RequestMethod.POST, consumes = { "multipart/form-data" })
    public ResponseEntity<String> addQuestion2(String question, @RequestPart("file") MultiPartFile file)  {
    QuestionPostDto dtoObject = new ObjectMapper().readValue(request, QuestionPostDto.class); 
    // do sth
}

Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW

------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="file"; filename="QLbLFIR.gif"
Content-Type: image/gif


------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="request"

{
    "key": "value"
}
------WebKitFormBoundary7MA4YWxkTrZu0gW--

請參閱此線程以獲取更多詳細信息： 帶有JSON的Spring MVC多重請求

Answer 2

我解決了這個問題。

1）我創建了HttpMessageConverter，將json轉換為我的自定義類型QuestionPostDto：

public class QuestionPostDtoHttpMessageConverter implements HttpMessageConverter<QuestionPostDto> {

    @Override
    public boolean canRead(Class<?> clazz, MediaType mediaType) {
        return QuestionPostDto.class == clazz;
    }

    @Override
    public boolean canWrite(Class<?> clazz, MediaType mediaType) {
        return QuestionPostDto.class == clazz;
    }

    @Override
    public List<MediaType> getSupportedMediaTypes() {
        List<MediaType> list = new ArrayList<MediaType>();
        list.add(MediaType.MULTIPART_FORM_DATA);
        return list;
    }

    @Override
    public QuestionPostDto read(Class<? extends QuestionPostDto> clazz, HttpInputMessage inputMessage)
            throws IOException, HttpMessageNotReadableException {
        InputStream istream = inputMessage.getBody();
        String requestString = IOUtils.toString(istream, "UTF-8");

        ObjectMapper mapper = new ObjectMapper();
        return mapper.readValue(requestString, QuestionPostDto.class);
    }

    @Override
    public void write(QuestionPostDto t, MediaType contentType, HttpOutputMessage outputMessage)
            throws IOException, HttpMessageNotWritableException {
    }
}

2）我為此類型的HttpMessageConverter創建bean（我們在項目中使用Spring Boot）：

@Configuration
public class HttpConfiguration {
...
    @Bean
    public QuestionPostDtoHttpMessageConverter commonsMultipartResolver() {
        return new QuestionPostDtoHttpMessageConverter();
    }
}

3）現在我在RestController中的代碼可以正常工作：

@RestController
@RequestMapping("/api/question")
@ConfigurationProperties(prefix = "question")
@RequiredArgsConstructor
@Slf4j
public class QuestionController {
...
@PostMapping
ResponseEntity<String> addQuestion(@RequestPart("dtoObject") QuestionPostDto dtoObject, @RequestPart("file") MultipartFile file) { ... }

感謝大家，尤其是Chi Dov