10. Rxjava2 : 重試

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
retry {{retry}}
retryUntil {{retryUntil}}
retryWhen {{retryWhen}}
repeat {{repeat}}
repeatUntil {{repeatUntil}}
repeatWhen {{repeatWhen}}

retry

  • retry
    1.觸發retry最重要的條件是看時候會發射throwable(與repeat對比)
    2.沒有任何參數指定的時候,會無限次重試{{demo0}}
    3.指定重試的次數{{demo1}}
    4.指定終止條件{{demo2}}
    5.指定重試次數以及終止條件,則兩條有一條滿足即終止,其余均與3,4同

  • demo0 :
    無限重試

Observable.create((ObservableOnSubscribe<Integer>) e -> {
            e.onNext(1);
            e.onNext(2);
            e.onNext(3);
            e.onError(new NullPointerException());
            e.onNext(4);
        }).retry()
                .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 13:39:06.431 23097-23097/... D/SplashActivity: integer:1
02-13 13:39:06.431 23097-23097/... D/SplashActivity: integer:2
02-13 13:39:06.431 23097-23097/... D/SplashActivity: integer:3
02-13 13:39:06.431 23097-23097/... D/SplashActivity: integer:1
02-13 13:39:06.431 23097-23097/... D/SplashActivity: integer:2
02-13 13:39:06.431 23097-23097/... D/SplashActivity: integer:3
02-13 13:39:06.431 23097-23097/... D/SplashActivity: integer:1
02-13 13:39:06.431 23097-23097/... D/SplashActivity: integer:2
02-13 13:39:06.431 23097-23097/... D/SplashActivity: integer:3
  • demo1 :
    自身發送一次
    重試兩次
    在第三次的時候碰到error,以onError作為終止標識
Observable.create((ObservableOnSubscribe<Integer>) e -> {
            e.onNext(1);
            e.onNext(2);
            e.onNext(3);
            e.onError(new NullPointerException());
            e.onNext(4);
        }).retry(2)
                .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 13:42:41.231 24025-24025/... D/SplashActivity: integer:1
02-13 13:42:41.231 24025-24025/... D/SplashActivity: integer:2
02-13 13:42:41.231 24025-24025/... D/SplashActivity: integer:3
02-13 13:42:41.231 24025-24025/... D/SplashActivity: integer:1
02-13 13:42:41.231 24025-24025/... D/SplashActivity: integer:2
02-13 13:42:41.231 24025-24025/... D/SplashActivity: integer:3
02-13 13:42:41.231 24025-24025/... D/SplashActivity: integer:1
02-13 13:42:41.231 24025-24025/... D/SplashActivity: integer:2
02-13 13:42:41.231 24025-24025/... D/SplashActivity: integer:3
02-13 13:42:41.231 24025-24025/... D/SplashActivity: onError
  • demo2 :
    指定終止條件
    以onError作為終止標識
    需要注意的是:
    參數1是從1開始記,并不是從0
    第三次檢測是否需要重試,條件并不滿足,所以是重試了2次
Observable.create((ObservableOnSubscribe<Integer>) e -> {
            e.onNext(1);
            e.onNext(2);
            e.onNext(3);
            e.onError(new NullPointerException());
            e.onNext(4);
        }).retry(new BiPredicate<Integer, Throwable>() {
            @Override
            public boolean test(Integer integer, Throwable throwable) throws Exception {
                Log.d(TAG, "檢測是否需要重試:" + integer);
                return integer < 3;
            }
        })
                .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 13:58:33.771 26179-26179/... D/SplashActivity: integer:1
02-13 13:58:33.771 26179-26179/... D/SplashActivity: integer:2
02-13 13:58:33.771 26179-26179/... D/SplashActivity: integer:3
02-13 13:58:33.771 26179-26179/... D/SplashActivity: 檢測是否需要重試:1
02-13 13:58:33.771 26179-26179/... D/SplashActivity: integer:1
02-13 13:58:33.771 26179-26179/... D/SplashActivity: integer:2
02-13 13:58:33.771 26179-26179/... D/SplashActivity: integer:3
02-13 13:58:33.771 26179-26179/... D/SplashActivity: 檢測是否需要重試:2
02-13 13:58:33.771 26179-26179/... D/SplashActivity: integer:1
02-13 13:58:33.771 26179-26179/... D/SplashActivity: integer:2
02-13 13:58:33.771 26179-26179/... D/SplashActivity: integer:3
02-13 13:58:33.771 26179-26179/... D/SplashActivity: 檢測是否需要重試:3
02-13 13:58:33.771 26179-26179/... D/SplashActivity: onError

retryUntil

  • retryUntil
    1.需注意判定條件: (與retry相反)
    true:不再重試
    false:繼續重試
    2.一般用于外界指定停止條件
Observable.create((ObservableOnSubscribe<Integer>) e -> {
            e.onNext(1);
            e.onNext(2);
            e.onNext(3);
            e.onError(new NullPointerException());
            e.onNext(4);
        }).retryUntil(new BooleanSupplier() {
            @Override
            public boolean getAsBoolean() throws Exception {
                //true 則不繼續重試
                //false 一直重試
                i++;
                Log.d(TAG, "進入檢測了,i = " + i);
                return i > 2;
            }
        }).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 14:15:09.471 27881-27881/... D/SplashActivity: integer:1
02-13 14:15:09.471 27881-27881/... D/SplashActivity: integer:2
02-13 14:15:09.471 27881-27881/... D/SplashActivity: integer:3
02-13 14:15:09.471 27881-27881/... D/SplashActivity: 進入檢測了,i = 1
02-13 14:15:09.471 27881-27881/... D/SplashActivity: integer:1
02-13 14:15:09.471 27881-27881/... D/SplashActivity: integer:2
02-13 14:15:09.471 27881-27881/... D/SplashActivity: integer:3
02-13 14:15:09.471 27881-27881/... D/SplashActivity: 進入檢測了,i = 2
02-13 14:15:09.471 27881-27881/... D/SplashActivity: integer:1
02-13 14:15:09.471 27881-27881/... D/SplashActivity: integer:2
02-13 14:15:09.471 27881-27881/... D/SplashActivity: integer:3
02-13 14:15:09.471 27881-27881/... D/SplashActivity: 進入檢測了,i = 3
02-13 14:15:09.471 27881-27881/... D/SplashActivity: onError

retryWhen

  • retryWhen
    返回一個Observable
    1.這個返回的Observable當中可以正常返回的數目,代表的是原Observable發送的次數(重試次數-1)
    2.如果再次返回的Observable并不是以onError作為結束標識的,則整體會以onComplete作為結束標識
//返回了5,6兩個正常的元素,則會重試1次
Observable.create((ObservableOnSubscribe<Integer>) e -> {
            e.onNext(1);
            e.onNext(2);
            e.onNext(3);
            e.onError(new NullPointerException());
            e.onNext(4);
        }).retryWhen(new Function<Observable<Throwable>, ObservableSource<?>>() {
            @Override
            public ObservableSource<?> apply(Observable<Throwable> throwableObservable) throws Exception {
                return Observable.create(new ObservableOnSubscribe<Integer>() {
                    @Override
                    public void subscribe(ObservableEmitter<Integer> e) throws Exception {
                        e.onNext(5);
                        e.onNext(6);
                        e.onError(new NullPointerException());
                    }
                });
            }
        }).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 14:29:50.331 28805-28805/com.showdemo D/SplashActivity: integer:1
02-13 14:29:50.331 28805-28805/com.showdemo D/SplashActivity: integer:2
02-13 14:29:50.331 28805-28805/com.showdemo D/SplashActivity: integer:3
02-13 14:29:50.331 28805-28805/com.showdemo D/SplashActivity: integer:1
02-13 14:29:50.331 28805-28805/com.showdemo D/SplashActivity: integer:2
02-13 14:29:50.331 28805-28805/com.showdemo D/SplashActivity: integer:3
02-13 14:29:50.331 28805-28805/com.showdemo D/SplashActivity: onError

//如果直接返回error,則原Observable發送的也不會接收
Observable.create((ObservableOnSubscribe<Integer>) e -> {
            e.onNext(1);
            e.onNext(2);
            e.onNext(3);
            e.onError(new NullPointerException());
            e.onNext(4);
        }).retryWhen(new Function<Observable<Throwable>, ObservableSource<?>>() {
            @Override
            public ObservableSource<?> apply(Observable<Throwable> throwableObservable) throws Exception {
                return Observable.create(new ObservableOnSubscribe<Integer>() {
                    @Override
                    public void subscribe(ObservableEmitter<Integer> e) throws Exception {
                        e.onError(new NullPointerException());
                    }
                });
            }
        }).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 14:33:00.351 29108-29108/... D/SplashActivity: onError

//返回的Observable并不是以onError作為結束標識
 Observable.create((ObservableOnSubscribe<Integer>) e -> {
            e.onNext(1);
            e.onNext(2);
            e.onNext(3);
            e.onError(new NullPointerException());
        })
                .retryWhen(new Function<Observable<Throwable>, ObservableSource<?>>() {
                    @Override
                    public ObservableSource<?> apply(Observable<Throwable> throwableObservable) throws Exception {
                        return Observable.just(4,5);
                    }
                }).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 14:43:54.841 30166-30166/... D/SplashActivity: integer:1
02-13 14:43:54.841 30166-30166/... D/SplashActivity: integer:2
02-13 14:43:54.841 30166-30166/... D/SplashActivity: integer:3
02-13 14:43:54.841 30166-30166/... D/SplashActivity: integer:1
02-13 14:43:54.841 30166-30166/... D/SplashActivity: integer:2
02-13 14:43:54.841 30166-30166/... D/SplashActivity: integer:3
02-13 14:43:54.841 30166-30166/... D/SplashActivity: onComplete

repeat

  • repeat
    repeat與retry功能類似,只是retry需要error來進行觸發,而repeat則并不需要
Observable.just(1,2,3)
                .repeatWhen(new Function<Observable<Object>, ObservableSource<?>>() {
                    @Override
                    public ObservableSource<?> apply(Observable<Object> objectObservable) throws Exception {
                        return Observable.create(new ObservableOnSubscribe<Integer>() {
                            @Override
                            public void subscribe(ObservableEmitter<Integer> e) throws Exception {
                                e.onNext(4);
                                e.onNext(5);
                                e.onError(new NullPointerException());
                            }
                        });
                    }
                }).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 14:38:51.091 29551-29551/... D/SplashActivity: integer:1
02-13 14:38:51.091 29551-29551/... D/SplashActivity: integer:2
02-13 14:38:51.091 29551-29551/... D/SplashActivity: integer:3
02-13 14:38:51.091 29551-29551/... D/SplashActivity: integer:1
02-13 14:38:51.091 29551-29551/... D/SplashActivity: integer:2
02-13 14:38:51.091 29551-29551/... D/SplashActivity: integer:3
02-13 14:38:51.091 29551-29551/... D/SplashActivity: onError
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