RxJava2 / RxAndroid2的过滤器filter

- 日理万妓 2024-02-17 22:07 19阅读 0赞

**RxJava2 / RxAndroid2的过滤器filter**

filter完成一个条件过滤和筛选，从Observable的输出数据中，经过filter筛选一层，如果filter判断的值为真，则交给观察者，否则跳过，例如代码：

package zhangphil.app;
    
    import android.os.Bundle;
    import android.support.annotation.Nullable;
    import android.support.v7.app.AppCompatActivity;
    import android.util.Log;
    
    import io.reactivex.Observable;
    import io.reactivex.android.schedulers.AndroidSchedulers;
    import io.reactivex.disposables.CompositeDisposable;
    import io.reactivex.functions.Predicate;
    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<Integer>() {
                @Override
                public void onNext(Integer i) {
                    Log.d(TAG, "#####开始#####");
                    Log.d(TAG + "数据", String.valueOf(i));
                    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(
                    getObservable().filter(new Predicate<Integer>() {
                        @Override
                        public boolean test(Integer integer) throws Exception {
                            int result = integer % 10;
                            boolean b = (result == 0);
                            return b; // 此处返回的条件若为true，则数据交给观察者 ,否则跳过
                        }
                    })
                            .subscribeOn(Schedulers.io())
                            .observeOn(AndroidSchedulers.mainThread())
                            .subscribeWith(disposableObserver));
        }
    
        private Observable<Integer> getObservable() {
            return Observable.range(0, 100);
        }
    
        @Override
        protected void onDestroy() {
            super.onDestroy();
    
            // 如果退出程序，就清除后台任务
            mCompositeDisposable.clear();
        }
    }

代码输出：

05-15 17:15:49.664 29872-29872/zhangphil.app D/MainActivity: #####开始#####
    05-15 17:15:49.664 29872-29872/zhangphil.app D/MainActivity数据: 0
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 10
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 20
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 30
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 40
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 50
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 60
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 70
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 80
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 90
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
    05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: onComplete