Resttemplate表单/Multipart:image+JSON在

Question

    HttpHeaders header = new HttpHeaders();
    header.setContentType(MediaType.MULTIPART_FORM_DATA);

    MultiValueMap<String, Object> map = new LinkedMultiValueMap<>();
    ByteArrayResource bytes = new ByteArrayResource(pictureData) {
        @Override
        public String getFilename() {
            return pictureName;
        }
    };
    map.add("x", x);
    map.add("file", bytes);

    HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity(map, header);
    String response =  restTemplate.postForObject(UPLOAD_URL, requestEntity, String.class);

如果我将ByteArrayResource更改为Byte[]，那么我会得到一个400错误的请求。如果我将内容类型更改为JSON，那么ByteArrayResource就不能序列化为JSON：

Caused by: org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: No serializer found for class java.io.ByteArrayInputStream and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: org.springframework.util.LinkedMultiValueMap["file"]->java.util.LinkedList[0]->a.b.c.["inputStream"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class java.io.ByteArrayInputStream and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: org.springframework.util.LinkedMultiValueMap["file"]->java.util.LinkedList[0]->a.b.c.["inputStream"])

我配置了以下转换器：

StringHttpMessageConverter,
MappingJackson2HttpMessageConverter
FormHttpMessageConverter

有什么想法吗？提前谢了。

    RestTemplate restTemplate = new RestTemplate();
    restTemplate.getMessageConverters().add(new StringHttpMessageConverter());
    restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());

    FormHttpMessageConverter formHttpMessageConverter = new FormHttpMessageConverter();
        formHttpMessageConverter.addPartConverter(new MappingJackson2HttpMessageConverter());
        formHttpMessageConverter.addPartConverter(new ResourceHttpMessageConverter()); // This is hope driven programming

    restTemplate.getMessageConverters().add(new ResourceHttpMessageConverter());
    restTemplate.getMessageConverters().add(formHttpMessageConverter);

    HttpHeaders header = new HttpHeaders();
    header.setContentType(MediaType.APPLICATION_JSON); //Also tried with multipart...

    MultiValueMap<String, Object> multipartRequest = new LinkedMultiValueMap<>();

    ByteArrayResource bytes = new ByteArrayResource(pictureData) {
        @Override
        public String getFilename() {
            return pictureName;
        }
    };

    HttpHeaders xHeader = new HttpHeaders();
    xHeader.setContentType(MediaType.APPLICATION_JSON);
    HttpEntity<X> xPart = new HttpEntity<>(x, xHeader);
    multipartRequest.add("x", xPart);

    HttpHeaders pictureHeader = new HttpHeaders();
    pictureHeader.setContentType(MediaType.IMAGE_PNG);
    HttpEntity<ByteArrayResource> picturePart = new HttpEntity<>(bytes, pictureHeader);
    multipartRequest.add("file", picturePart);

    HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity(multipartRequest, header);
    return restTemplate.postForObject(UPLOAD_URL, requestEntity, String.class);

Answer 1

如果要使用ByteArrayResource，只需注册ResourceHttpMessageConverter。

如果要使用字节[]，只需注册ByteArrayHttpMessageConverter。

图像部分的内容类型应该是图像类型，比如image/png，而不是application/json。

HttpHeaders partHeaders = new HttpHeaders();
partHeaders.setContentType(MediaType.IMAGE_PNG);
HttpEntity<ByteArrayResource> bytesPart = new HttpEntity<ByteArrayResource>(bytes, partHeaders);

map.add("file", bytesPart);

HttpMessageConverter<Object> jackson = new MappingJackson2HttpMessageConverter();
HttpMessageConverter<Resource> resource = new ResourceHttpMessageConverter();
FormHttpMessageConverter formHttpMessageConverter = new FormHttpMessageConverter();
formHttpMessageConverter.addPartConverter(jackson);
formHttpMessageConverter.addPartConverter(resource); // This is hope driven programming

RestTemplate restTemplate = new RestTemplate(Arrays.asList(jackson, resource, formHttpMessageConverter));

header.setContentType(MediaType.MULTIPART_FORM_DATA);