如何用RxAndroid和Retrofit 2檢索響應體？

Question

我正在使用Retrofit 2（測試版4），並且我正在尋求從使用標準Call響應到RxAndroid Observable響應。我通過從Call<List<ExampleObject>>到Observable<List<ExampleObject>>的簡單交換成功地切換了我的大部分電話。我的一些電話的使用Call<okhttp3.ResponseBody>，偉大的工程，但是當我換出Call，我遇到了一個錯誤：

03-03 15:21:44.237 27333-27333/com.example.app E/AndroidRuntime: FATAL EXCEPTION: main 
     Process: com.example.app, PID: 27333 
     java.lang.IllegalArgumentException: Unable to create call adapter for rx.Observable<okhttp3.ResponseBody> 
      for method AuthenticationService.getLoginForm 
      at retrofit2.Utils.methodError(Utils.java:119) 
      at retrofit2.MethodHandler.createCallAdapter(MethodHandler.java:52) 
      at retrofit2.MethodHandler.create(MethodHandler.java:25) 
      at retrofit2.Retrofit.loadMethodHandler(Retrofit.java:164) 
      at retrofit2.Retrofit$1.invoke(Retrofit.java:145) 
      at java.lang.reflect.Proxy.invoke(Proxy.java:393) 
      at $Proxy6.getLoginForm(Unknown Source) 
      at com.example.app.ui.fragment.LoginFragment.login(LoginFragment.java:214) 
      at com.example.app.ui.fragment.LoginFragment.lambda$onContinue$1(LoginFragment.java:168) 
      at com.example.app.ui.fragment.LoginFragment.access$lambda$1(LoginFragment.java) 
      at com.example.app.ui.fragment.LoginFragment$$Lambda$4.onClick(Unknown Source) 
      at android.view.View.performClick(View.java:5204) 
      at android.view.View$PerformClick.run(View.java:21153) 
      at android.os.Handler.handleCallback(Handler.java:739) 
      at android.os.Handler.dispatchMessage(Handler.java:95) 
      at android.os.Looper.loop(Looper.java:148) 
      at android.app.ActivityThread.main(ActivityThread.java:5417) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
     Caused by: java.lang.IllegalArgumentException: Could not locate call adapter for rx.Observable<okhttp3.ResponseBody>. 
     Tried: 
      * retrofit2.ExecutorCallAdapterFactory 
      at retrofit2.Retrofit.nextCallAdapter(Retrofit.java:230) 
      at retrofit2.Retrofit.callAdapter(Retrofit.java:194) 
      at retrofit2.MethodHandler.createCallAdapter(MethodHandler.java:50) 
       ... 18 more 

的原因，我現在用的是ResponseBody代替另一個對象像往常一樣，是因爲在這些情況我需要解析HTML，並且據我所知，HTML解析器沒有Retrofit轉換器。我知道我可能會自己創建一個，但我寧願不要爲我需要解析的少量HTML。

我的問題是爲什麼改造2 RxJava適配器支持ResponseBody當改造2本身呢？有沒有另一種方法可以從Observable獲得響應字符串？

---

我的服務：

public interface AuthenticationService() { 

    @GET("cas/login") 
    Observable<Response<ResponseBody>> login(); 
} 

相關改造代碼：

public static Retrofit getRetrofit() { 
    if(mRetrofit == null) { 
     return new Retrofit.Builder() 
       .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) 
       .addConverterFactory(GsonConverterFactory.create(getGson())) 
       .client(getOkHttpClient()) 
       .build(); 
    } return mRetrofit; 
} 

public static AuthenticationService getAuthenticationService() { 
    return getRetrofit().create(AuthenticationService.class); 
} 

響應嘗試：

private void login() { 
    RestClient.getAuthenticationService().login() 
      .observeOn(ASchedulers.newThread()) 
      .subscribeOn(AndroidSchedulers.mainThread()) 
      .doOnNext(this::onLoginResponse); 
} 

private void onLoginResponse(Response<ResponseBody>> response) { 
    try { 
     parseResponse(response.body().string()); 
    } catch (IOException) { 
     Timber.w(throwable, "Failed to login"); 
    } 
} 

新的堆棧跟蹤：

03-03 16:14:57.848 26866-26866/com.example.app E/AndroidRuntime: FATAL EXCEPTION: main 
     Process: com.example.app, PID: 26866 
     java.lang.IllegalArgumentException: Unable to create call adapter for rx.Observable<retrofit2.Response<okhttp3.ResponseBody>> 
      for method AuthenticationService.getLoginForm 
      at retrofit2.Utils.methodError(Utils.java:119) 
      at retrofit2.MethodHandler.createCallAdapter(MethodHandler.java:52) 
      at retrofit2.MethodHandler.create(MethodHandler.java:25) 
      at retrofit2.Retrofit.loadMethodHandler(Retrofit.java:164) 
      at retrofit2.Retrofit$1.invoke(Retrofit.java:145) 
      at java.lang.reflect.Proxy.invoke(Proxy.java:393) 
      at $Proxy3.getLoginForm(Unknown Source) 
      at com.example.app.ui.fragment.LoginFragment.login(LoginFragment.java:206) 
      at com.example.app.ui.fragment.LoginFragment.lambda$onContinue$1(LoginFragment.java:160) 
      at com.example.app.ui.fragment.LoginFragment.access$lambda$1(LoginFragment.java) 
      at com.example.app.ui.fragment.LoginFragment$$Lambda$4.onClick(Unknown Source) 
      at android.view.View.performClick(View.java:5204) 
      at android.view.View$PerformClick.run(View.java:21153) 
      at android.os.Handler.handleCallback(Handler.java:739) 
      at android.os.Handler.dispatchMessage(Handler.java:95) 
      at android.os.Looper.loop(Looper.java:148) 
      at android.app.ActivityThread.main(ActivityThread.java:5417) 
      at java.lang.reflect.Method.invoke(Native Method) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
     Caused by: java.lang.IllegalArgumentException: Could not locate call adapter for rx.Observable<retrofit2.Response<okhttp3.ResponseBody>>. 
     Tried: 
      * retrofit2.ExecutorCallAdapterFactory 
      at retrofit2.Retrofit.nextCallAdapter(Retrofit.java:230) 
      at retrofit2.Retrofit.callAdapter(Retrofit.java:194) 
      at retrofit2.MethodHandler.createCallAdapter(MethodHandler.java:50) 
       ... 18 more 

Answer 1

嘗試這樣：

import okhttp3.ResponseBody; 
import retrofit2.Response; 

@GET("/whatever") 
Observable<Response<ResponseBody>> getWhatever(); 

編輯：不要忘了，你必須指定RxJava適配器：

new Retrofit.Builder() 
      ... 
      .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) 
      .build() 
      .create(Api.class);