How can I return String or JSONObject from asynchronous callback using Retrofit?

Question

For example, calling

api.getUserName(userId, new Callback<String>() {...}); 

cause:

retrofit.RetrofitError: retrofit.converter.ConversionException: com.google.gson.JsonSyntaxException: java.lang.IllegalStateException:  Expected a string but was BEGIN_OBJECT at line 1 column 2 

I think I must disable gson parsing into POJOs but can't figure out how to do it.

Answer 1

I figured it out. It's embarrassing but it was very simple... Temporary solution may be like this:

 public void success(Response response, Response ignored) {             TypedInput body = response.getBody();             try {                 BufferedReader reader = new BufferedReader(new InputStreamReader(body.in()));                 StringBuilder out = new StringBuilder();                 String newLine = System.getProperty("line.separator");                 String line;                 while ((line = reader.readLine()) != null) {                     out.append(line);                     out.append(newLine);                 }                  // Prints the correct String representation of body.                  System.out.println(out);             } catch (IOException e) {                 e.printStackTrace();             }         } 

But if you want to get directly Callback the Better way is to use Converter.

public class Main { public interface ApiService {     @GET("/api/")     public void getJson(Callback<String> callback); }  public static void main(String[] args) {     RestAdapter restAdapter = new RestAdapter.Builder()             .setClient(new MockClient())             .setConverter(new StringConverter())             .setEndpoint("http://www.example.com").build();      ApiService service = restAdapter.create(ApiService.class);     service.getJson(new Callback<String>() {         @Override         public void success(String str, Response ignored) {             // Prints the correct String representation of body.             System.out.println(str);         }          @Override         public void failure(RetrofitError retrofitError) {             System.out.println("Failure, retrofitError" + retrofitError);         }     }); }  static class StringConverter implements Converter {      @Override     public Object fromBody(TypedInput typedInput, Type type) throws ConversionException {         String text = null;         try {             text = fromStream(typedInput.in());         } catch (IOException ignored) {/*NOP*/ }          return text;     }      @Override     public TypedOutput toBody(Object o) {         return null;     }      public static String fromStream(InputStream in) throws IOException {         BufferedReader reader = new BufferedReader(new InputStreamReader(in));         StringBuilder out = new StringBuilder();         String newLine = System.getProperty("line.separator");         String line;         while ((line = reader.readLine()) != null) {             out.append(line);             out.append(newLine);         }         return out.toString();     } }  public static class MockClient implements Client {     @Override     public Response execute(Request request) throws IOException {         URI uri = URI.create(request.getUrl());         String responseString = "";          if (uri.getPath().equals("/api/")) {             responseString = "{result:\"ok\"}";         } else {             responseString = "{result:\"error\"}";         }          return new Response(request.getUrl(), 200, "nothing", Collections.EMPTY_LIST,                 new TypedByteArray("application/json", responseString.getBytes()));     }   } } 

If you know how to improve this code - please feel free to write about it.