Android版Spring-无法提取响应：找不到适合响应类型的HttpMessageConverter

Question

I'm trying to retrieve some data from a REST service using spring for Android. However I'm running into problems. I'm also using Robospice - and as such have a method like so:

 public FunkyThingsList loadDataFromNetwork() throws Exception {
        String baseURI =context.getResources().getString(R.string.baseWebServiceURI);
                String uri = baseURI + "/FunkyThings/date/" + dateToLookUp.toString("yyyy-MM-dd");
        RestTemplate restTemplate = getRestTemplate();
        final HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
        headers.setAccept( Arrays.asList(MediaType.APPLICATION_JSON));
        HttpAuthentication authHeader = new HttpBasicAuthentication(username, password);
        headers.setAuthorization(authHeader);

        // Create the request body as a MultiValueMap
        MultiValueMap<String, String> map = new LinkedMultiValueMap<String, String>();
        HttpMessageConverter<String> stringConverter = new StringHttpMessageConverter();
        FormHttpMessageConverter formConverter = new FormHttpMessageConverter();
        List<HttpMessageConverter<?>> msgConverters = restTemplate.getMessageConverters();
        msgConverters.add(formConverter);
        msgConverters.add(stringConverter);
        restTemplate.setMessageConverters(msgConverters);

        HttpEntity<?> httpEntity = new HttpEntity<Object>(map, headers);
        final ResponseEntity<FunkyThingsList> responseEntity = restTemplate.exchange(url, HttpMethod.GET, httpEntity,FunkyThingsList.class);

        return responseEntity.getBody();
    }

Unfortunately this isn't working. I'm getting the following exception thrown:

org.springframework.web.client.RestClientException: Could not extract response: no suitable HttpMessageConverter found for response type [com.MyProject.DataClassPojos.RoboSpiceArrayLists.FunkyThingsList] and content type [application/json;charset=utf-8]

Now based on my Googling I get the feeling I need to add a message converter. I'm just not sure which message converter I need, or where I add it?

Answer 1

For the default JSON HttpMessageConverter , you'll need to add either Jackson 1 or Jackson 2 to your classpath.

Otherwise, you can add some other JSON library and write your own HttpMessageConverter which can do the deserialization. You add it to the RestTemplate . You can either use the constructor or this method .

Answer 2

If you are following the Spring for Android tutorial and you get the same error - this might be of help:

In your MainActivity.java:

...
RestTemplate restTemplate = new RestTemplate();
MappingJacksonHttpMessageConverter converter = new
MappingJacksonHttpMessageConverter();    
converter.setSupportedMediaTypes(Collections.singletonList(MediaType.TEXT_HTML));
restTemplate.getMessageConverters().add(converter);

Use the converter in the call and configure it to use as a Media Type the TEXT_HTML, then use the instance of the converter.

Also the tutorial is a bit outdated so use the latest versions as suggested here in your build.gradle:

dependencies{
 //Spring Framework for REST calls and Jackson for JSON processing
 compile 'org.springframework.android:spring-android-rest-template:2.0.0.M3'

 compile 'com.fasterxml.jackson.core:jackson-databind:2.4.1.3'
}
repositories {
 maven {
    url 'https://repo.spring.io/libs-milestone'
 }
}