I am trying use rxJava, rxAndroid, Retrofit2, and OkHTTP3 to download a file from a URL endpoint. My code is unable to create the call adapter for an "Observable< retrofit2.Response< okhttp3.ResponseBody>>". These methods are new to me so I believe I'm missing an important concept here. Any direction or points is greatly appreciated.
FATAL EXCEPTION: main Process: com.example.khe11e.rxdownloadfile, PID: 14130 java.lang.IllegalArgumentException: Unable to create call adapter for io.reactivex.Observable> for method RetrofitInterface.downloadFileByUrlRx at retrofit2.ServiceMethod$Builder.methodError(ServiceMethod.java:720) at retrofit2.ServiceMethod$Builder.createCallAdapter(ServiceMethod.java:234) at retrofit2.ServiceMethod$Builder.build(ServiceMethod.java:160) at retrofit2.Retrofit.loadServiceMethod(Retrofit.java:166) at retrofit2.Retrofit$1.invoke(Retrofit.java:145) at java.lang.reflect.Proxy.invoke(Proxy.java:393) at $Proxy0.downloadFileByUrlRx(Unknown Source) at com.example.khe11e.rxdownloadfile.MainActivity.downloadImage(MainActivity.java:46) at com.example.khe11e.rxdownloadfile.MainActivity$1.onClick(MainActivity.java:39) at android.view.View.performClick(View.java:5207) at android.view.View$PerformClick.run(View.java:21168) at android.os.Handler.handleCallback(Handler.java:746) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5491) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) Caused by: java.lang.IllegalArgumentException: Could not locate call adapter for io.reactivex.Observable>. Tried: * retrofit2.adapter.rxjava.RxJavaCallAdapterFactory * retrofit2.ExecutorCallAdapterFactory at retrofit2.Retrofit.nextCallAdapter(Retrofit.java:237) at retrofit2.Retrofit.callAdapter(Retrofit.java:201) at retrofit2.ServiceMethod$Builder.createCallAdapter(ServiceMethod.java:232) ... 16 more
build.gradle:
compile 'io.reactivex.rxjava2:rxandroid:2.0.1'
compile 'io.reactivex.rxjava2:rxjava:2.0.4'
compile 'com.squareup.retrofit2:retrofit:2.1.0'
compile 'com.squareup.retrofit2:adapter-rxjava:2.1.0'
RetrofitInterface.java:
package com.example.khe11e.rxdownloadfile;
import io.reactivex.Observable;
import okhttp3.ResponseBody;
import retrofit2.Call;
import retrofit2.Response;
import retrofit2.http.GET;
import retrofit2.http.Streaming;
import retrofit2.http.Url;
public interface RetrofitInterface {
// Retrofit 2 GET request for rxjava
@Streaming
@GET
Observable<Response<ResponseBody>> downloadFileByUrlRx(@Url String fileUrl);
}
MainActivity.java:
package com.example.khe11e.rxdownloadfile;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import java.io.File;
import io.reactivex.Observable;
import io.reactivex.ObservableEmitter;
import io.reactivex.ObservableOnSubscribe;
import io.reactivex.Observer;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.disposables.Disposable;
import io.reactivex.functions.Function;
import io.reactivex.schedulers.Schedulers;
import okhttp3.OkHttpClient;
import okhttp3.ResponseBody;
import okio.BufferedSink;
import okio.Okio;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.adapter.rxjava.RxJavaCallAdapterFactory;
public class MainActivity extends AppCompatActivity {
Button downloadImgBtn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
downloadImgBtn = (Button) findViewById(R.id.downloadImgBtn);
downloadImgBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
downloadImage();
}
});
}
public void downloadImage(){
RetrofitInterface downloadService = createService(RetrofitInterface.class, "https://www.nasa.gov/");
downloadService.downloadFileByUrlRx("sites/default/files/iss_1.jpg")
.flatMap(processResponse())
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(handleResult());
}
public <T> T createService(Class<T> serviceClass, String baseUrl){
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(baseUrl)
.client(new OkHttpClient.Builder().build())
.addCallAdapterFactory(RxJavaCallAdapterFactory.create()).build();
return retrofit.create(serviceClass);
}
public Function<Response<ResponseBody>, Observable<File>> processResponse(){
return new Function<Response<ResponseBody>, Observable<File>>() {
@Override
public Observable<File> apply(Response<ResponseBody> responseBodyResponse) throws Exception {
return saveToDiskRx(responseBodyResponse);
}
};
}
private Observable<File> saveToDiskRx(final Response<ResponseBody> response){
return Observable.create(new ObservableOnSubscribe<File>() {
@Override
public void subscribe(ObservableEmitter<File> subscriber) throws Exception {
String header = response.headers().get("Content-Disposition");
String filename = header.replace("attachment; filename=", "");
new File("/data/data/" + getPackageName() + "/images").mkdir();
File destinationFile = new File("/data/data/" + getPackageName() + "/images/" + filename);
BufferedSink bufferedSink = Okio.buffer(Okio.sink(destinationFile));
bufferedSink.writeAll(response.body().source());
bufferedSink.close();
subscriber.onNext(destinationFile);
subscriber.onComplete();
}
});
}
private Observer<File> handleResult(){
return new Observer<File>() {
@Override
public void onSubscribe(Disposable d) {
Log.d("OnSubscribe", "OnSubscribe");
}
@Override
public void onNext(File file) {
Log.d("OnNext", "File downloaded to " + file.getAbsolutePath());
}
@Override
public void onError(Throwable e) {
e.printStackTrace();
Log.d("Error", "Error " + e.getMessage());
}
@Override
public void onComplete() {
Log.d("OnComplete", "onCompleted");
}
};
}
}
I've tried adding Call as mentioned here so it looks like:
Call<Observable<Response<ResponseBody>>> downloadFileByUrlRx(@Url String fileUrl);
however this causes issues with the flatMap function as it cannot find symbol method flatMap(Function< Response< ResponseBody>,Observable< File>>).
