FATAL EXCEPTION: 主要 进程：com.example.khe11e.rxdownloadfile，PID：14130 java.lang.IllegalArgumentException：无法为io.reactivex.Observable>创建调用适配器 RetrofitInterface.downloadFileByUrlRx方法中 在retrofit2.ServiceMethod$Builder.methodError（ServiceMethod.java:720）处 在retrofit2.ServiceMethod$Builder.createCallAdapter（ServiceMethod.java:234）处 在retrofit2.ServiceMethod$Builder.build（ServiceMethod.java:160）处 在retrofit2.Retrofit.loadServiceMethod（Retrofit.java:166）处 在retrofit2.Retrofit$1.invoke（Retrofit.java:145）处 在java.lang.reflect.Proxy.invoke（Proxy.java:393）处 在$ Proxy0.downloadFileByUrlRx（未知来源）处 在com.example.khe11e.rxdownloadfile.MainActivity.downloadImage（MainActivity.java:46）处 在com.example.khe11e.rxdownloadfile.MainActivity $ 1.onClick（MainActivity.java:39）处 在android.view.View.performClick（View.java:5207）处 在android.view.View $ PerformClick.run（View.java:21168）处 在android.os.Handler.handleCallback（Handler.java:746）处 在android.os.Handler.dispatchMessage（Handler.java:95）处 在android.os.Looper.loop（Looper.java:148）处 在android.app.ActivityThread.main（ActivityThread.java:5491）处 在java.lang.reflect.Method.invoke（Native Method）处 在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:728）处 在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:618）处 原因是：java.lang.IllegalArgumentException：无法找到io.reactivex.Observable>的调用适配器。 已尝试： *retrofit2.adapter.rxjava.RxJavaCallAdapterFactory *retrofit2.ExecutorCallAdapterFactory 在retrofit2.Retrofit.nextCallAdapter（Retrofit.java:237）处 在retrofit2.Retrofit.callAdapter（Retrofit.java:201）处 在retrofit2.ServiceMethod$Builder.createCallAdapter（ServiceMethod.java:232）处 ... 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");
}
};
}
}
我尝试着按照这里提到的方式添加Call，代码如下：
Call<Observable<Response<ResponseBody>>> downloadFileByUrlRx(@Url String fileUrl);
然而，这会导致flatMap函数出现问题，因为它找不到符号方法flatMap（Function< Response< ResponseBody>,Observable< File>>）。
RxJava2CallAdapterFactory.create（）而不是RxJavaCallAdapterFactory.create（）。 - eC Droidcom.squareup.retrofit2:adapter-rxjava3:2.9.0中。 - AdamHurwitz