我如何使用改造从异步回调返回字符串或JSONObject的？

Question

例如，调用

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

原因：

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

我想我必须禁用GSON解析成的POJO，但无法弄清楚如何做到这一点。

Answer 1

我想通了。这是令人尴尬的，但它是非常简单的...... 临时解决可能是这样的：

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(); 
      } 
     } 

但是，如果你想获得直接回调更好的办法是使用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())); 
    } 
    } 
} 

如果你知道如何改进此代码 - 请随时写下它。

Answer 2

可能的解决方案是使用JsonElement作为Callback类型（Callback<JsonElement>）。在原来的例子：

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

在成功的方法，你可以将JsonElement转换到任何一个String或JsonObject。

JsonObject jsonObj = element.getAsJsonObject(); 
String strObj = element.toString(); 

Answer 3

当@lordmegamax回答完全工作存在被来自

Okio is a new library that complements java.io and java.nio

其他广场项目，该项目与retrofit，因此已经紧你不需要添加任何新的依赖和更漂亮的解决方案它必须是可靠的：

ByteString.read(body.in(), (int) body.length()).utf8(); 

ByteString is an immutable sequence of bytes. For character data, String is fundamental. ByteString is String's long-lost brother, making it easy to treat binary data as a value. This class is ergonomic: it knows how to encode and decode itself as hex, base64, and UTF-8.

完整的示例：

public class StringConverter implements Converter { 
    @Override public Object fromBody(TypedInput body, Type type) throws ConversionException { 
    try { 
     return ByteString.read(body.in(), (int) body.length()).utf8(); 
    } catch (IOException e) { 
     throw new ConversionException("Problem when convert string", e); 
    } 
    } 

    @Override public TypedOutput toBody(Object object) { 
    return new TypedString((String) object); 
    } 
} 

Answer 4

答案可能远小于已经提到的，并且不需要任何额外的库：

在声明中使用Response如下：

... Callback<Response> callback); 

而且在处理响应：

@Override 
public void success(Response s, Response response) { 
    new JSONObject(new String(((TypedByteArray) response.getBody()).getBytes())) 
} 

Answer 5

Retrofit 2.0.0-beta3 adds a converter-scalars module provides a Converter.Factory for converting String , the 8 primitive types, and the 8 boxed primitive types as text/plain bodies. Install this before your normal converter to avoid passing these simple scalars through, for example, a JSON converter.

所以，先加converter-scalars模块build.gradle文件为您的应用程序。

dependencies { 
    ... 
    // use your Retrofit version (requires at minimum 2.0.0-beta3) instead of 2.0.0 
    // also do not forget to add other Retrofit module you needed 
    compile 'com.squareup.retrofit2:converter-scalars:2.0.0' 
} 

然后，创建你的Retrofit实例是这样的：

new Retrofit.Builder() 
     .baseUrl(BASE_URL) 
     // add the converter-scalars for coverting String 
     .addConverterFactory(ScalarsConverterFactory.create()) 
     .addConverterFactory(GsonConverterFactory.create()) 
     .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) 
     .build() 
     .create(Service.class); 

现在你可以使用API​​的声明是这样的：

interface Service { 

    @GET("https://stackoverflow.com/users/{id}/name") 
    Call<String> userName(@Path("userId") String userId); 

    // RxJava version 
    @GET("https://stackoverflow.com/users/{id}/name") 
    Observable<String> userName(@Path("userId") String userId); 
} 

Answer 6

这是我做什么，在打探后调试器。注意：这是为了在错误回调中实际获取它，而不是成功回调。

你会看到成功的类型是通过调用retrofitError.getSuccessType()和回报和类型的对象中找到Type

你可以调用retrofitError.getBodyAs(YourType.class)这是所有我需要我，因为做其始终类我希望它成为。

这里是一个班轮答案：

retrofitError.getBodyAs(retrofitError.getSuccessType()) 

现在，我会注意到，我没有做任何事情像这对于成功回调，因为它已经奇迹般地工作。

Answer 7

为了获得呼叫的JSONObject或JSONArray

您可以创建自定义的工厂或从这里复制：https://github.com/marcinOz/Retrofit2JSONConverterFactory