java Resttemplate 表单/多部分：POST 中的图像 + JSON

Resttemplate form/multipart: image + JSON in POST

提问by TamasGyorfi

I'm trying to call a rest ws (using resttemplate), that accepts an image and some JSON. However, I don't seem to be able to get it running.

我正在尝试调用一个rest ws（使用resttemplate），它接受一个图像和一些JSON。但是，我似乎无法让它运行。

The relevant code is as follows:

相关代码如下：

    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);

Where x is some POJO with all the required JSON annotations (I receive it from another web service, that part works ok).

其中 x 是一些带有所有必需 JSON 注释的 POJO（我从另一个 Web 服务收到它，那部分工作正常）。

This thing, however, tells me: HttpMessageNotWritableException: Could not write request: no suitable HttpMessageConverter found for x.

但是，这件事告诉我：HttpMessageNotWritableException：无法写入请求：找不到适合 x 的 HttpMessageConverter。

If I change ByteArrayResource to byte[] then I get a 400 Bad Request. If I change the content type to JSON, then ByteArrayResource cannot be serialized into JSON:

如果我将 ByteArrayResource 更改为 byte[]，则会收到 400 Bad Request。如果我将内容类型更改为 JSON，则 ByteArrayResource 无法序列化为 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.Hymanson.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"])

I have the following converters configured:

我配置了以下转换器：

StringHttpMessageConverter,
MappingHymanson2HttpMessageConverter
FormHttpMessageConverter

Any ideas, please? Thanks in advance.

有什么想法吗？提前致谢。

UPDATE

更新

So this is what I currently have after the instructions: I register the converters like this:

所以这就是我在指令之后目前所拥有的：我像这样注册转换器：

    RestTemplate restTemplate = new RestTemplate();
    restTemplate.getMessageConverters().add(new StringHttpMessageConverter());
    restTemplate.getMessageConverters().add(new MappingHymanson2HttpMessageConverter());

    FormHttpMessageConverter formHttpMessageConverter = new FormHttpMessageConverter();
        formHttpMessageConverter.addPartConverter(new MappingHymanson2HttpMessageConverter());
        formHttpMessageConverter.addPartConverter(new ResourceHttpMessageConverter()); // This is hope driven programming

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

Then in the ws call I have:

然后在 ws 电话中我有：

    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);

采纳答案by Sotirios Delimanolis

If you want to use ByteArrayResource, simply register a ResourceHttpMessageConverter.

如果您想使用ByteArrayResource，只需注册一个ResourceHttpMessageConverter.

If you want to use a byte[], simply register a ByteArrayHttpMessageConverter.

如果您想使用byte[]，只需注册一个ByteArrayHttpMessageConverter。

The content type of the image part should be an image type, like image/png, not application/json.

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

You can set each individual part's data type with

您可以设置每个单独部件的数据类型

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

map.add("file", bytesPart);

---

---

Create your RestTemplateby providing your collection of HttpMessageConverters

RestTemplate通过提供您的HttpMessageConverters集合来创建您的

HttpMessageConverter<Object> Hymanson = new MappingHymanson2HttpMessageConverter();
HttpMessageConverter<Resource> resource = new ResourceHttpMessageConverter();
FormHttpMessageConverter formHttpMessageConverter = new FormHttpMessageConverter();
formHttpMessageConverter.addPartConverter(Hymanson);
formHttpMessageConverter.addPartConverter(resource); // This is hope driven programming

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

and your outermost HttpEntityshould have a multipart content type

并且你最外面的HttpEntity应该有一个多部分的内容类型

header.setContentType(MediaType.MULTIPART_FORM_DATA);