RxJava2 / RxAndroid2的concat拼接多个Observable

偏执的太偏执、 2024-02-17 22:07 46阅读 0赞

**RxJava2 / RxAndroid2的concat拼接多个Observable**

concat操作符和merge类似，把多个Observable拼接成一个可以观察的输出，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() {
                    Log.d(TAG, "onComplete");
                }
    
                @Override
                public void onError(Throwable e) {
                    Log.e(TAG, e.toString(), e);
                }
            };
    
            mCompositeDisposable.add(
                    Observable.concat(
                            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";
                }
            });
        }
    }

输出：

05-15 14:39:18.667 14456-14456/zhangphil.app D/MainActivity: #####开始#####
    05-15 14:39:18.667 14456-14456/zhangphil.app D/MainActivity数据: A
    05-15 14:39:18.667 14456-14456/zhangphil.app D/MainActivity: #####结束#####
    05-15 14:39:19.669 14456-14456/zhangphil.app D/MainActivity: #####开始#####
    05-15 14:39:19.669 14456-14456/zhangphil.app D/MainActivity数据: B
    05-15 14:39:19.669 14456-14456/zhangphil.app D/MainActivity: #####结束#####
    05-15 14:39:20.170 14456-14456/zhangphil.app D/MainActivity: #####开始#####
    05-15 14:39:20.170 14456-14456/zhangphil.app D/MainActivity数据: A
    05-15 14:39:20.170 14456-14456/zhangphil.app D/MainActivity: #####结束#####
    05-15 14:39:21.171 14456-14456/zhangphil.app D/MainActivity: #####开始#####
    05-15 14:39:21.172 14456-14456/zhangphil.app D/MainActivity数据: B
    05-15 14:39:21.172 14456-14456/zhangphil.app D/MainActivity: #####结束#####
    05-15 14:39:21.172 14456-14456/zhangphil.app D/MainActivity: onComplete