7. Rxjava2 : 合并操作符

1. RxJava2 : 什么是觀察者模式
2. RxJava2 : 創建操作符(無關時間)
3. Rxjava2 : 創建操作符(有關時間)
4. Rxjava2 : 變換操作符
5. Rxjava2 : 判斷操作符
6. Rxjava2 : 篩選操作符
7. Rxjava2 : 合并操作符
8. Rxjava2 : do操作符
9. Rxjava2 : error處理
10. Rxjava2 : 重試
11. Rxjava2 : 線程切換

api use
concat / concatArray {{concat}}
concatDelayError {{concatDelayError}}
merge / mergeArray {{merge}}
mergeDelayError {{mergeDelayError}}
zip {{zip}}
reduce {{reduce}}
collect {collect}
startWith / startWithArray {{startWith}}

concat / concatArray

  • concat
    1.concat的參數不得超過4個(不能超過4個Observable)
    2.concat是按照順序合并的
  • concatArray
    concatArray如果參數超過4個(就將Observable組成集合傳入),剩下的均與concat相同

流程

3個Observable一共有9個元素
Observable0(元素1,元素2,元素3)
Observable1(元素4,元素5,元素6)
Observable2(元素7,元素8,元素9)
->
按照順序合并元素
(元素1,元素2,元素3,元素4,元素5,元素6,元素7,元素8,元素9)
->
subscribe
->
observer 觀察到9個元素

        Observable<Integer> observable0 = Observable.just(1, 2, 3);
        Observable<Integer> observable1 = Observable.just(4, 5, 6);
        Observable<String> observable2 = Observable.just("7", "8", "9");
        Observable.concat(observable0, observable1, observable2)
                .subscribe(new Observer<Serializable>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onNext(Serializable serializable) {
                        if (serializable instanceof Integer) {
                            Log.d(TAG, "Integer:" + serializable);
                        } else if (serializable instanceof String) {
                            Log.d(TAG, "String:" + serializable);
                        }
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError");
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });

log

02-12 17:42:57.603 6230-6230/... D/SplashActivity: Integer:1
02-12 17:42:57.603 6230-6230/... D/SplashActivity: Integer:2
02-12 17:42:57.603 6230-6230/... D/SplashActivity: Integer:3
02-12 17:42:57.603 6230-6230/... D/SplashActivity: Integer:4
02-12 17:42:57.603 6230-6230/... D/SplashActivity: Integer:5
02-12 17:42:57.603 6230-6230/... D/SplashActivity: Integer:6
02-12 17:42:57.603 6230-6230/... D/SplashActivity: String:7
02-12 17:42:57.603 6230-6230/... D/SplashActivity: String:8
02-12 17:42:57.603 6230-6230/... D/SplashActivity: String:9
02-12 17:42:57.603 6230-6230/... D/SplashActivity: onComplete

concatDelayError

  • concatDelayError
    1.將onError放在了最后執行,那么onError就無法作為結束標識了,只能依靠onComplete作為結束標識
    2.能否執行onError取決于能否找到onComplete標識
    3.采用concat的方式,即按照元素順序合并,Observable0的complete失去作用,能否執行onError就取決于Observable1是否有結束標識
    4.以onError結束,則不會執行onComplete

流程

Observable
->
Observable0(元素1,元素2,元素3,throwable,complete)
Observable1(元素4,元素5,complete)
->
元素1,元素2,元素3,元素4,元素5,complete
->
元素1,元素2,元素3,元素4,元素5,throwable
->
subscribe
-> 
observer
->
log throwable

//Observable1具有e.onComplete()結束標識
 Observable<Integer> observable = Observable.create(e -> {
            e.onNext(1);
            e.onNext(2);
            e.onNext(3);
            e.onError(new NullPointerException());
            e.onComplete();
        });
        Observable<Integer> observable2 = Observable.create(e -> {
            e.onNext(4);
            e.onNext(5);
            e.onComplete();
        });
        List<Observable<Integer>> objects = new ArrayList<>();
        objects.add(observable);
        objects.add(observable2);
        Observable.concatDelayError(objects)
                .subscribe(new Observer<Integer>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onNext(Integer integer) {
                        Log.d(TAG, "integer:" + integer);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError");
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });

log

02-12 17:57:01.083 7281-7281/... D/SplashActivity: integer:1
02-12 17:57:01.083 7281-7281/... D/SplashActivity: integer:2
02-12 17:57:01.083 7281-7281/... D/SplashActivity: integer:3
02-12 17:57:01.093 7281-7281/... D/SplashActivity: integer:4
02-12 17:57:01.093 7281-7281/... D/SplashActivity: integer:5
02-12 17:57:01.093 7281-7281/... D/SplashActivity: onError

//Observable1不具有e.onComplete()結束標識
Observable<Integer> observable = Observable.create(e -> {
            e.onNext(1);
            e.onNext(2);
            e.onNext(3);
            e.onError(new NullPointerException());
            e.onComplete();
        });
        Observable<Integer> observable2 = Observable.create(e -> {
            e.onNext(4);
            e.onNext(5);
        });
        List<Observable<Integer>> objects = new ArrayList<>();
        objects.add(observable);
        objects.add(observable2);
        Observable.concatDelayError(objects)
                .subscribe(new Observer<Integer>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onNext(Integer integer) {
                        Log.d(TAG, "integer:" + integer);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError");
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });

log

02-12 18:03:27.353 8228-8228/... D/SplashActivity: integer:1
02-12 18:03:27.353 8228-8228/... D/SplashActivity: integer:2
02-12 18:03:27.353 8228-8228/... D/SplashActivity: integer:3
02-12 18:03:27.353 8228-8228/... D/SplashActivity: integer:4
02-12 18:03:27.353 8228-8228/... D/SplashActivity: integer:5

merge

  • merge
    1.merge的參數不得超過4個(不能超過4個Observable)
    2.merge是按照時間合并的
  • mergeArray
    mergeArray如果參數超過4個(就將Observable組成集合傳入),剩下的均與concat相同

流程

時間(秒) 0 1 2 3 4 5 6 7 8
Observable0 沒發送 沒發送 1 沒發送 沒發送 2 沒發送 沒發送 3
Observable1 沒發送 4 沒發送 沒發送 5 沒發送 沒發送 6 沒發送
Observable2 沒發送 7 沒發送 沒發送 8 沒發送 沒發送 9 沒發送

依照時間來合并:
則是 4,7,1,5,8,2,6,9,3

Log.d(TAG, "in");
        Observable<Long> longObservable = Observable
                .intervalRange(1, 3, 2, 2, TimeUnit.SECONDS);
        Observable<Long> longObservable1 = Observable
                .intervalRange(4, 3, 1, 2, TimeUnit.SECONDS);
        Observable<Long> longObservable2 = Observable
                .intervalRange(7, 3, 1, 2, TimeUnit.SECONDS);
        Observable
                .merge(longObservable, longObservable1,longObservable2)
                .subscribe(new Observer<Long>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onNext(Long aLong) {
                        Log.d(TAG, "aLong:" + aLong);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError");
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });

log

02-13 09:33:04.121 13228-13228/... D/SplashActivity: in
02-13 09:33:05.121 13228-13271/... D/SplashActivity: aLong:4
02-13 09:33:05.121 13228-13272/... D/SplashActivity: aLong:7
02-13 09:33:06.131 13228-13270/... D/SplashActivity: aLong:1
02-13 09:33:07.131 13228-13271/... D/SplashActivity: aLong:5
02-13 09:33:07.131 13228-13272/... D/SplashActivity: aLong:8
02-13 09:33:08.131 13228-13270/... D/SplashActivity: aLong:2
02-13 09:33:09.131 13228-13271/... D/SplashActivity: aLong:6
02-13 09:33:09.131 13228-13272/... D/SplashActivity: aLong:9
02-13 09:33:10.121 13228-13270/... D/SplashActivity: aLong:3
02-13 09:33:10.121 13228-13270/... D/SplashActivity: onComplete

mergeDelayError

  • mergeDelayError
    與concatDelayError類似,onError會在最后接收到
    區別在于:
    concatDelayError:
    會以最后一個onComplete作為結束的標識
    mergeDelayError:
    在時間過程當中,哪個Observable出現了error,哪個Observable就不再繼續發送了,直至所有Observable的元素都結束之后,處理onError

流程

時間 0 1 2
Observable0 1 throwable 2
Observable1 3 4 5,complete
合并 1,3 throwable,4 error結束,5,complete

則最后的結果為: 1,3,4,5,onError;

注意:在示例中,我采取了指定不同的線程做延時,如果在相同線程中,會出現卡線程的情況,會影響到結果

Log.d(TAG, "in");
        Observable<Long> longObservable = Observable.create((ObservableOnSubscribe<Long>) e -> {
            e.onNext(1L);
            Thread.sleep(1000);
            e.onError(new NullPointerException());
            Thread.sleep(1000);
            e.onNext(2L);
            e.onComplete();
        }).subscribeOn(Schedulers.newThread());
        Observable<Long> longObservable1 = Observable.create((ObservableOnSubscribe<Long>) e -> {
            e.onNext(3L);
            Thread.sleep(1000);
            e.onNext(4L);
            Thread.sleep(1000);
            e.onNext(5L);
            e.onComplete();
        }).subscribeOn(Schedulers.newThread());
        Observable
                .mergeDelayError(longObservable, longObservable1)
                .subscribe(new Observer<Long>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onNext(Long aLong) {
                        Log.d(TAG, "aLong:" + aLong);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError");
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });

log

02-13 10:03:26.701 16418-16418/... D/SplashActivity: in
02-13 10:03:26.711 16418-16463/... D/SplashActivity: aLong:1
02-13 10:03:26.711 16418-16464/... D/SplashActivity: aLong:3
02-13 10:03:27.721 16418-16464/... D/SplashActivity: aLong:4
02-13 10:03:28.711 16418-16464/... D/SplashActivity: aLong:5
02-13 10:03:28.711 16418-16464/... D/SplashActivity: onError

zip

  • zip
    必須嚴格遵守一一對應的關系

流程

observable 元素 元素 元素 元素
observable0 1 2 3 無
observable1 4 5 onComplete 6
zip合并(相加) 5 7 onComplete 碰到onComplete標識,已經結束

最終的結果 5,7

Observable<Integer> observable = Observable.create(e -> {
            e.onNext(1);
            e.onNext(2);
            e.onNext(3);
        });
        Observable<Integer> observable1 = Observable.create(e -> {
            e.onNext(4);
            e.onNext(5);
            e.onComplete();
            e.onNext(6);
        });
        Observable
                .zip(observable, observable1,
                        (integer, integer2) -> integer + integer2)
                .subscribe(new Observer<Integer>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onNext(Integer integer) {
                        Log.d(TAG, "integer:" + integer);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError");
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });

log

02-01 11:25:53.581 11233-11233/... D/ShellAppApplication: integer:5
02-01 11:25:53.581 11233-11233/... D/ShellAppApplication: integer:7

Observable<Integer> observable = Observable.create(e -> {
            e.onError(new NullPointerException());
            e.onNext(2);
            e.onNext(3);
        });
        Observable<Integer> observable1 = Observable.create(e -> {
            e.onNext(4);
            e.onNext(5);
            e.onComplete();
            e.onNext(6);
        });
        Observable
                .zip(observable, observable1,
                        (integer, integer2) ->  integer + integer2)
                .subscribe(new Observer<Integer>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onNext(Integer integer) {
                        Log.d(TAG, "integer:" + integer);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError");
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });

log

02-13 10:34:54.131 17980-17980/... D/SplashActivity: onError

reduce

  • reduce
    對于同一個Observable當中的所有元素逐一處理,合并為同一個元素

流程

observable(元素1,元素2,元素3)
->
reduce
->
apply (元素1,元素2) -> 元素X
apply(元素X,元素3) -> (元素X +元素3) 作為新的元素X 
遞歸,直至最后一個

-> 
one observable
->
subscribe

Disposable subscribe = Observable.just(1, 2, 3).reduce((integer, integer2) -> {
            Log.d(TAG, "first:" + integer);
            Log.d(TAG, "second:" + integer2);
            return integer + integer2;
        }).subscribe(integer -> Log.d(TAG, "integer:" + integer));

log

02-01 15:41:32.261 4709-4709/... D/ShellAppApplication: first:1
02-01 15:41:32.261 4709-4709/... D/ShellAppApplication: second:2
02-01 15:41:32.261 4709-4709/... D/ShellAppApplication: first:3
02-01 15:41:32.261 4709-4709/... D/ShellAppApplication: second:3
02-01 15:41:32.261 4709-4709/... D/ShellAppApplication: integer:6

collect

  • collect
    收集
    1.指定一個容器
    2.將所有的元素收集到這個容器當中
Disposable subscribe = Observable.just(1, 2, 3)
                .collect(new Callable<List<Integer>>() {
                    @Override
                    public List<Integer> call() throws Exception {
                        return new ArrayList<>();
                    }
                }, new BiConsumer<List<Integer>, Integer>() {
                    @Override
                    public void accept(List<Integer> list, Integer integer) throws Exception {
                        list.add(integer);
                    }
                })
                .subscribe(new Consumer<List<Integer>>() {
                    @Override
                    public void accept(List<Integer> integers) throws Exception {
                        Log.d(TAG, "integers:" + integers);
                    }
                });

log

02-13 10:49:49.061 18664-18664/... D/SplashActivity: integers:[1, 2, 3]

startWith

  • startWith
    在最開始的時候插入
    1.支持插入單一元素
    2.支持插入Observable
Observable.just(1, 2, 3)
                .startWith(0)
                .subscribe(new Observer<Integer>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onNext(Integer integer) {
                        Log.d(TAG, "integer:" + integer);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError");
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });

log

02-13 10:53:59.151 18992-18992/... D/SplashActivity: integer:0
02-13 10:53:59.151 18992-18992/... D/SplashActivity: integer:1
02-13 10:53:59.151 18992-18992/... D/SplashActivity: integer:2
02-13 10:53:59.151 18992-18992/... D/SplashActivity: integer:3
02-13 10:53:59.151 18992-18992/... D/SplashActivity: onComplete

Observable.just(1, 2, 3)
                .startWith(Observable.just(4, 5, 6))
                .subscribe(new Observer<Integer>() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

                    @Override
                    public void onNext(Integer integer) {
                        Log.d(TAG, "integer:" + integer);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError");
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });

log

02-13 10:55:14.241 19238-19238/... D/SplashActivity: integer:4
02-13 10:55:14.241 19238-19238/... D/SplashActivity: integer:5
02-13 10:55:14.241 19238-19238/... D/SplashActivity: integer:6
02-13 10:55:14.241 19238-19238/... D/SplashActivity: integer:1
02-13 10:55:14.241 19238-19238/... D/SplashActivity: integer:2
02-13 10:55:14.241 19238-19238/... D/SplashActivity: integer:3
02-13 10:55:14.241 19238-19238/... D/SplashActivity: onComplete
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