RxJava2 / RxAndroid2的merge操作合并多个Observable

RxAndroid2/RxJava2的merge操作合并若干个Observable为单个可观测的Observable，形成单一线性的Observable输出结果，例如代码：

package zhangphil.app; import android.os.Bundle; import android.support.annotation.NonNull; import android.support.annotation.Nullable; import android.support.v7.app.AppCompatActivity; import android.util.Log; import java.util.concurrent.Callable; import io.reactivex.Observable; import io.reactivex.android.schedulers.AndroidSchedulers; import io.reactivex.disposables.CompositeDisposable; import io.reactivex.functions.BiFunction; import io.reactivex.observers.DisposableObserver; import io.reactivex.schedulers.Schedulers; public class MainActivity extends AppCompatActivity { private final String TAG = getClass().getSimpleName(); private CompositeDisposable mCompositeDisposable = new CompositeDisposable(); @Override public void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); test(); } private void test() { DisposableObserver disposableObserver = new DisposableObserver<String>() { @Override public void onNext(String s) { Log.d(TAG, "#####开始#####"); Log.d(TAG + "数据", String.valueOf(s)); Log.d(TAG, "#####结束#####"); } @Override public void onComplete() { } @Override public void onError(Throwable e) { Log.e(TAG, e.toString(), e); } }; mCompositeDisposable.add( Observable.merge( getObservableA(null), getObservableB(null), getObservableA(null), getObservableB(null)) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribeWith(disposableObserver)); } @Override protected void onDestroy() { super.onDestroy(); // 如果退出程序，就清除后台任务 mCompositeDisposable.clear(); } private Observable<String> getObservableA(Object o) { return Observable.fromCallable(new Callable<String>() { @Override public String call() throws Exception { try { Thread.sleep(500); // 假设此处是耗时操作 } catch (Exception e) { e.printStackTrace(); } return "A"; } }); } private Observable<String> getObservableB(Object o) { return Observable.fromCallable(new Callable<String>() { @Override public String call() throws Exception { try { Thread.sleep(1000); // 假设此处是耗时操作 } catch (Exception e) { e.printStackTrace(); } return "B"; } }); } } 

代码输出结果：

05-15 13:40:41.929 12972-12972/zhangphil.app D/MainActivity: #####开始##### 05-15 13:40:41.929 12972-12972/zhangphil.app D/MainActivity数据: A 05-15 13:40:41.929 12972-12972/zhangphil.app D/MainActivity: #####结束##### 05-15 13:40:42.930 12972-12972/zhangphil.app D/MainActivity: #####开始##### 05-15 13:40:42.930 12972-12972/zhangphil.app D/MainActivity数据: B 05-15 13:40:42.930 12972-12972/zhangphil.app D/MainActivity: #####结束##### 05-15 13:40:43.430 12972-12972/zhangphil.app D/MainActivity: #####开始##### 05-15 13:40:43.431 12972-12972/zhangphil.app D/MainActivity数据: A 05-15 13:40:43.431 12972-12972/zhangphil.app D/MainActivity: #####结束##### 05-15 13:40:44.431 12972-12972/zhangphil.app D/MainActivity: #####开始##### 05-15 13:40:44.431 12972-12972/zhangphil.app D/MainActivity数据: B 05-15 13:40:44.431 12972-12972/zhangphil.app D/MainActivity: #####结束#####