RxJava2

工程导入

compile 'io.reactivex.rxjava2:rxjava:2.1.5'
compile 'io.reactivex.rxjava2:rxandroid:2.0.1'

Observable：在观察者模式中称为“被观察者”；
Observer：观察者模式中的“观察者”，可接收Observable发送的数据；
subscribe：订阅，观察者与被观察者，通过subscribe()方法进行订阅；
Subscriber：也是一种观察者，在2.0中 它与Observer没什么实质的区别，不同的是 Subscriber要与Flowable(也是一种被观察者)联合使用，该部分内容是2.0新增的。Obsesrver用于订阅Observable，而Subscriber用于订阅Flowable

1. 最简单的天气观测

当天气发生变化时，把天气变化发送给各个观测者

创建天气
 enum Weather{
        WIND,SUNSHINE
    }
模拟天气变化
Observable observable = new Observable() {
            @Override
            protected void subscribeActual(Observer observer) {
                observer.onNext(Weather.WIND);
                observer.onNext(Weather.SUNSHINE);
            }
        };
用户
Observer user = new Observer() {
            @Override
            public void onSubscribe(@NonNull Disposable d) {

            }

            @Override
            public void onNext(@NonNull Weather o) {
                Log.e("tag","天气:"+o);
            }

            @Override
            public void onError(@NonNull Throwable e) {

            }

            @Override
            public void onComplete() {

            }
        };
订阅
observable.subscribe(user);

日志输出:
tag: 天气:WIND
tag: 天气:SUNSHINE

更简单的写法

Observable.create(new ObservableOnSubscribe() {
            @Override
            public void subscribe(@NonNull ObservableEmitter e) throws Exception {
                e.onNext(Weather.WIND);
                e.onNext(Weather.SUNSHINE);
            }
        }).subscribe(new Observer() {
            @Override
            public void onSubscribe(@NonNull Disposable d) {

            }

            @Override
            public void onNext(@NonNull Weather weather) {
                Log.e("tag","天气:"+weather);
            }

            @Override
            public void onError(@NonNull Throwable e) {

            }

            @Override
            public void onComplete() {

            }
        });

Observable.just(Weather.WIND,Weather.SUNSHINE).subscribe(new Observer() {
            @Override
            public void onSubscribe(@NonNull Disposable d) {

            }

            @Override
            public void onNext(@NonNull Weather weather) {
                Log.e("tag","天气:"+weather);
            }

            @Override
            public void onError(@NonNull Throwable e) {

            }

            @Override
            public void onComplete() {

            }
        });

Weather weather[]={Weather.WIND,Weather.SUNSHINE};
        Observable.fromArray(weather).subscribe(new Observer() {
            @Override
            public void onSubscribe(@NonNull Disposable d) {

            }

            @Override
            public void onNext(@NonNull Weather weather) {
                Log.e("tag","天气:"+weather);
            }

            @Override
            public void onError(@NonNull Throwable e) {

            }

            @Override
            public void onComplete() {

            }
        });

2. 操作符

map

数据类型转换，一对一

 Weather weather[] = {Weather.WIND, Weather.SUNSHINE};
        Observable.fromArray(weather)
//第一个泛型为接收参数的数据类型，第二个泛型为转换后要发射的数据类型即把weather转为string
                .map(new Function() {
                    @Override
                    public String apply(@NonNull Weather weather) throws Exception {
                        return weather.toString();
                    }
                })
                .subscribe(new Observer() {
                    @Override
                    public void onSubscribe(@NonNull Disposable d) {

                    }

                    @Override
                    public void onNext(@NonNull String weather) {
                        Log.e("tag", "天气:" + weather);
                    }

                    @Override
                    public void onError(@NonNull Throwable e) {

                    }

                    @Override
                    public void onComplete() {

                    }
                });

flatMap

flatMap和map有共同点的，都是将一个对象转换为另一个对象，不同的是map只是一对一的转换，而flatMap可以是一对多的转换，并且是转换为另外一个Observable对象！

enum Weather {
        WIND, SUNSHINE,RAIN,SNOW
    }

        Weather weather1[] = {Weather.WIND, Weather.SUNSHINE};
        Weather weather2[] = {Weather.RAIN, Weather.SNOW};
        List list = new ArrayList<>();
        list.add(weather1);
        list.add(weather2);

        Observable.fromIterable(list)
                .flatMap(new Function>() {
                    @Override
                    public ObservableSource apply(@NonNull Weather[] weathers) throws Exception {
                        return Observable.fromArray(weathers);
                    }
                }).subscribe(new Consumer() {
            @Override
            public void accept(Weather weather) throws Exception {
                Log.e("tag","天气:"+weather);
            }
        });

输出日志:
tag: 天气:WIND
tag: 天气:SUNSHINE
tag: 天气:RAIN
tag: 天气:SNOW

调度器

DE9BCBFA-BCA8-44DB-B360-BCDC6D04BFEC.png

android主线程:AndroidSchedulers.mainThread()

线程切换:
Observable.fromIterable(list)
                .flatMap(new Function>() {
                    @Override
                    public ObservableSource apply(@NonNull Weather[] weathers) throws Exception {
                        return Observable.fromArray(weathers);
                    }
                })
                .subscribeOn(Schedulers.io())//指定观察物的运行线程
                .observeOn(AndroidSchedulers.mainThread())//指定观测者收到结果的运行线程
                .subscribe(new Consumer() {
            @Override
            public void accept(Weather weather) throws Exception {
                Log.e("tag","天气:"+weather);
            }
        });

doOnSubscribe

如果情景为：打开进度dialog，并进行网络请求，需要使用

 Observable.fromIterable(list)
                .flatMap(new Function>() {
                    @Override
                    public ObservableSource apply(@NonNull Weather[] weathers) throws Exception {
                        return Observable.fromArray(weathers);
                    }
                })
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .doOnSubscribe(new Consumer() {
                    @Override
                    public void accept(Disposable disposable) throws Exception {
                        Toast.makeText(MainActivity.this,"模拟dialog",Toast.LENGTH_SHORT).show();
                    }
                })
                .subscribe(new Consumer() {
            @Override
            public void accept(Weather weather) throws Exception {
                Log.e("tag","天气:"+weather);
            }
        });