Question

我正在一个项目中，我需要使用ocr从图像中获取数据。我正在第三方使用ocr，可以在其中上传文件并从ocr中获取数据。

我需要通过Spring Boot调用此API。这个api是multipart / form-data。

我创建了一个接受文件的函数，并尝试创建一个请求以将该文件发布到外部api。我遇到错误

"message": "Type definition error: [simple type, class java.io.FileDescriptor]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class java.io.FileDescriptor and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: 

org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile[\"inputStream\"]->java.io.FileInputStream[\"fd\"])",

控制器方法：

@PostMapping(value = "/ocrImage")
    public  ResponseEntity<GenericResponse> ocrImage(@RequestParam("file") MultipartFile file) {

        Object ocrDataImage = ocrService.ocrImage(file);
        return ResponseBuilder.buildResponse(ocrDataImage , 0, "");
    }

已调用服务

public Object ocrImage(MultipartFile file) {

    // adding headers to the api
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.MULTIPART_FORM_DATA);
    headers.set("x-key", API_KEY);

    MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
    body.add("file", file);


    HttpEntity<MultiValueMap<String, Object>> requestEntity= new HttpEntity<>(body, headers);

    RestTemplate restTemplate = new RestTemplate();
    Object result = restTemplate.postForEntity(EXTERNAL_API_ENDPOINT, requestEntity,
            String.class);

    System.out.println(result);
    return result;

}

调用postForEntity时，出现上述错误。

如果您需要更多详细信息，请告诉我。

Answer 1

要在使用springboot时禁用空豆失败，可以设置以下属性：

application.properties

spring.jackson.serialization.FAIL_ON_EMPTY_BEANS=false

或者您可以在对象映射器中手动设置它，例如：

@Bean
public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
    ObjectMapper mapper = new ObjectMapper();
    mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
    MappingJackson2HttpMessageConverter converter = 
        new MappingJackson2HttpMessageConverter(mapper);
    return converter;
}

Answer 2

我通过在本地存储文件解决了该问题。在调用第三方API时，我给出了此文件的位置，并且该文件可以正常工作。

在控制器方法中：

@PostMapping(value = "/ocrImage")
public  ResponseEntity<GenericResponse> ocrImage(@RequestParam("file") MultipartFile file) {

    // I have created a function to store file locally and return the absolute path
    String fileName = fileStorageService.storeFile(file);

    // passing the filepath to the service method
    Object ocrDataImage = ocrService.ocrImage(fileName);
    return ResponseBuilder.buildResponse(ocrDataImage , 0, "");
}

已调用服务

public String ocrImage(String path) {

    // getting the file from disk
    FileSystemResource value = new FileSystemResource(new File(path));

    // adding headers to the api
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.MULTIPART_FORM_DATA);
    headers.set("x-key", API_KEY);

    MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
    body.add("file", value);


    HttpEntity<MultiValueMap<String, Object>> requestEntity= new HttpEntity<>(body, headers);

    RestTemplate restTemplate = new RestTemplate();
    String result = restTemplate.postForEntity(EXTERNAL_API_ENDPOINT, requestEntity,
        String.class).getBody().toString();

    System.out.println(result);
    return result;
}

从Spring Boot使用multipart / form-data调用外部api

2 个答案: