[java] POST request via RestTemplate in JSON

I didn't find any example how to solve my problem, so I want to ask you for help. I can't simply send POST request using RestTemplate object in JSON

Every time I get:

org.springframework.web.client.HttpClientErrorException: 415 Unsupported Media Type

I use RestTemplate in this way:

...
restTemplate = new RestTemplate();
List<HttpMessageConverter<?>> list = new ArrayList<HttpMessageConverter<?>>();
list.add(new MappingJacksonHttpMessageConverter());
restTemplate.setMessageConverters(list);
...
Payment payment= new Payment("Aa4bhs");
Payment res = restTemplate.postForObject("http://localhost:8080/aurest/rest/payment", payment, Payment.class);

What is my fault?

If you dont want to process response

private RestTemplate restTemplate = new RestTemplate();
restTemplate.postForObject(serviceURL, request, Void.class);

If you need response to process

String result = restTemplate.postForObject(url, entity, String.class);

Why work harder than you have to? postForEntity accepts a simple Map object as input. The following works fine for me while writing tests for a given REST endpoint in Spring. I believe it's the simplest possible way of making a JSON POST request in Spring:

@Test
public void shouldLoginSuccessfully() {
  // 'restTemplate' below has been @Autowired prior to this
  Map map = new HashMap<String, String>();
  map.put("username", "bob123");
  map.put("password", "myP@ssw0rd");
  ResponseEntity<Void> resp = restTemplate.postForEntity(
      "http://localhost:8000/login",
      map,
      Void.class);
  assertThat(resp.getStatusCode()).isEqualTo(HttpStatus.OK);
}

This code is working for me;

RestTemplate restTemplate = new RestTemplate();
Payment payment = new Payment("Aa4bhs");
MultiValueMap<String, Object> map = new LinkedMultiValueMap<String, Object>();
map.add("payment", payment);
HttpEntity<MultiValueMap<String, Object>> httpEntity = new HttpEntity<MultiValueMap<String, Object>>(map, headerObject);

Payment res = restTemplate.postForObject(url, httpEntity, Payment.class);

For me error occurred with this setup:

AndroidAnnotations Spring Android RestTemplate Module and ...

GsonHttpMessageConverter

Android annotations has some problems with this converted to generate POST request without parameter. Simply parameter new Object() solved it for me.

I ran across this problem when attempting to debug a REST endpoint. Here is a basic example using Spring's RestTemplate class to make a POST request that I used. It took me quite a bit of a long time to piece together code from different places to get a working version.

RestTemplate restTemplate = new RestTemplate();

String url = "endpoint url";
String requestJson = "{\"queriedQuestion\":\"Is there pain in your hand?\"}";
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);

HttpEntity<String> entity = new HttpEntity<String>(requestJson,headers);
String answer = restTemplate.postForObject(url, entity, String.class);
System.out.println(answer);

The particular JSON parser my rest endpoint was using needed double quotes around field names so that's why I've escaped the double quotes in my requestJson String.

I'm doing in this way and it works .

HttpHeaders headers = createHttpHeaders(map);
public HttpHeaders createHttpHeaders(Map<String, String> map)
{   
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.APPLICATION_JSON);
    for (Entry<String, String> entry : map.entrySet()) {
        headers.add(entry.getKey(),entry.getValue());
    }
    return headers;
}

// Pass headers here

 String requestJson = "{ // Construct your JSON here }";
logger.info("Request JSON ="+requestJson);
HttpEntity<String> entity = new HttpEntity<String>(requestJson, headers);
ResponseEntity<String> response = restTemplate.exchange(url, HttpMethod.POST, entity, String.class);
logger.info("Result - status ("+ response.getStatusCode() + ") has body: " + response.hasBody());
logger.info("Response ="+response.getBody());

Hope this helps

This technique worked for me:

HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);

HttpEntity<String> entity = new HttpEntity<String>(requestJson, headers);
ResponseEntity<String> response = restTemplate.put(url, entity);

I hope this helps

I tried as following in spring boot:

ParameterizedTypeReference<Map<String, Object>> typeRef = new ParameterizedTypeReference<Map<String, Object>>() {};
public Map<String, Object> processResponse(String urlendpoint)
{
    try{
    
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_JSON);
        //reqobj
        JSONObject request = new JSONObject();
        request.put("username", name);
        //Or Hashmap 
        Map<String, Object> reqbody =  new HashMap<>();
        reqbody.put("username",username);
        Gson gson = new Gson();//mvn plugin to convert map to String
        HttpEntity<String> entity = new HttpEntity<>( gson.toJson(reqbody), headers);
        ResponseEntity<Map<String, Object>> response = resttemplate.exchange(urlendpoint, HttpMethod.POST, entity, typeRef);//example of post req with json as request payload
        if(Integer.parseInt(response.getStatusCode().toString()) == HttpURLConnection.HTTP_OK)
        {
            Map<String, Object>  responsedetails = response.getBody();
            System.out.println(responsedetails);//whole json response as map object
            return responsedetails;
        }
    } catch (Exception e) {
        // TODO: handle exception
        System.err.println(e);
    }
    return null;
}

I was getting this problem and I'm using Spring's RestTemplate on the client and Spring Web on the server. Both APIs have very poor error reporting, making them extremely difficult to develop with.

After many hours of trying all sorts of experiments I figured out that the issue was being caused by passing in a null reference for the POST body instead of the expected List. I presume that RestTemplate cannot determine the content-type from a null object, but doesn't complain about it. After adding the correct headers, I started getting a different server-side exception in Spring before entering my service method.

The fix was to pass in an empty List from the client instead of null. No headers are required since the default content-type is used for non-null objects.

If you are using Spring 3.0, an easy way to avoid the org.springframework.web.client.HttpClientErrorException: 415 Unsupported Media Type exception, is to include the jackson jar files in your classpath, and use mvc:annotation-driven config element. As specified here.

I was pulling my hair out trying to figure out why the mvc-ajax app worked without any special config for the MappingJacksonHttpMessageConverter. If you read the article I linked above closely:

Underneath the covers, Spring MVC delegates to a HttpMessageConverter to perform the serialization. In this case, Spring MVC invokes a MappingJacksonHttpMessageConverter built on the Jackson JSON processor. This implementation is enabled automatically when you use the mvc:annotation-driven configuration element with Jackson present in your classpath.

I've been using rest template with JSONObjects as follow:

// create request body
JSONObject request = new JSONObject();
request.put("username", name);
request.put("password", password);

// set headers
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<String> entity = new HttpEntity<String>(request.toString(), headers);

// send request and parse result
ResponseEntity<String> loginResponse = restTemplate
  .exchange(urlString, HttpMethod.POST, entity, String.class);
if (loginResponse.getStatusCode() == HttpStatus.OK) {
  JSONObject userJson = new JSONObject(loginResponse.getBody());
} else if (loginResponse.getStatusCode() == HttpStatus.UNAUTHORIZED) {
  // nono... bad credentials
}

The "415 Unsupported Media Type" error is telling you that the server will not accept your POST request. Your request is absolutely fine, it's the server that's mis-configured.

MappingJacksonHttpMessageConverter will automatically set the request content-type header to application/json, and my guess is that your server is rejecting that. You haven't told us anything about your server setup, though, so I can't really advise you on that.

As specified here I guess you need to add a messageConverter for MappingJacksonHttpMessageConverter

If you don't want to map the JSON by yourself, you can do it as follows:

RestTemplate restTemplate = new RestTemplate();
restTemplate.setMessageConverters(Arrays.asList(new MappingJackson2HttpMessageConverter()));
ResponseEntity<String> result = restTemplate.postForEntity(uri, yourObject, String.class);