RxJava2的API入门使用手记

最新推荐文章于 2020-08-12 22:20:19 发布

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最新推荐文章于 2020-08-12 22:20:19 发布

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本文链接：https://blog.youkuaiyun.com/qq_35611780/article/details/92797393

本文聚焦RxJava2在Java应用层的逻辑，介绍如何在maven项目中导入依赖，并着重讲解RxJava2的核心元素，包括Observable、Observer、Disposable、ObservableOnSubscribe和Emitter。同时，概述了任务调度器的使用场景。

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RxJava的主要使用场景是Android，本片文章只关注其Java逻辑，限于应用层。

maven项目导入依赖 =》pom.xml

<dependency>
    <groupId>io.reactivex.rxjava2</groupId>
    <artifactId>rxjava</artifactId>
    <version>2.0.3</version>
</dependency>

RxJava2主要有以下需要注意的5个元素：

Observable（被观察者、通过其创建可观察序列：create()方法、通过subscribe注册一个观察者）
Observer（观察者接受数据，subscribe方法参数）
Disposable（接口：dispose()方法和isDisposed()方法，用于取消订阅和获取当前订阅状态）
ObservableOnSubscribe（当订阅时触发调用，向订阅者发送数据用的接口）
Emitter（即，onNext()、onError()、onComplete）

任务调度器的几个使用场景

Observable<String> observable = Observable.create(new ObservableOnSubscribe<String>() {
    @Override
    public void subscribe(ObservableEmitter<String> observableEmitter) throws Exception {
        observableEmitter.onNext("Hello");
        observableEmitter.onComplete();
    }
}).subscribeOn(Schedulers.io());

public static Scheduler computation() {return RxJavaPlugins.onComputationScheduler(COMPUTATION);}

public static Scheduler io() {return RxJavaPlugins.onIoScheduler(IO);}

public static Scheduler trampoline() {return TRAMPOLINE;}

public static Scheduler newThread() {return RxJavaPlugins.onNewThreadScheduler(NEW_THREAD);}

public static Scheduler single() {return RxJavaPlugins.onSingleScheduler(SINGLE);}

1. 例子：

// 创建observable
Observable observable = Observable.create(new ObservableOnSubscribe<String>() {
    @Override
    public void subscribe(ObservableEmitter<String> observableEmitter) throws Exception {
        observableEmitter.onNext("I");
        observableEmitter.onNext("Love");
        observableEmitter.onComplete();
    }
});
// 线程变换
observable.subscribeOn(Schedulers.io());
// 创建Observer
Observer observer = new Observer<String>() {
    @Override
    public void onSubscribe(Disposable disposable) { System.out.println("订阅状态："+disposable.isDisposed()); }
    @Override
    public void onNext(String s) { System.out.println("onNext执行逻辑："+ s); }
    @Override
    public void onError(Throwable throwable) { System.out.println("onError"); }
    @Override
    public void onComplete() { System.out.println("onComplete"); }
};
// 订阅
observable.subscribe(observer);

//执行结果：
//订阅状态：false
//onNext执行逻辑：I
//onNext执行逻辑：Love 
//onComplete

2.API

=====================================================================

初始	Observable observable = Observable.create(new ObservableOnSubscribe<String>() { @Override public void subscribe(ObservableEmitter<String> observableEmitter) throws Exception { observableEmitter.onNext("I"); observableEmitter.onComplete(); } }); observable.subscribeOn(Schedulers.io()); Observer observer = new Observer<String>() { @Override public void onSubscribe(Disposable disposable) { System.out.println("订阅状态："+disposable.isDisposed()); } @Override public void onNext(String s) { System.out.println("onNext执行逻辑："+ s); } @Override public void onError(Throwable throwable) { System.out.println("onError"); } @Override public void onComplete() { System.out.println("onComplete"); } };
create	Observable observable = Observable.create(new ObservableOnSubscribe<String>() { @Override public void subscribe(ObservableEmitter<String> observableEmitter) throws Exception { observableEmitter.onNext("I"); observableEmitter.onComplete(); } });
just	// 发送的事件不超过10个 observable.just("1","2","3").subscribe(observer);
fromArray	// 发送事件超过10个，或者传入数组 observable.fromArray("1","......10").subscribe(observer); String array[] = {"1","2","3"}; observable.fromArray(array).subscribe(observer);
fromCallable
fromFuture
fromIterable	// 用于可以迭代的对象如List List<String> list = new ArrayList<>(); list.add("1");list.add("2");list.add("3"); observable.fromIterable(list).subscribe(observer);
timer	// 多长时间后开始执行onNext，并传入0L Observable.timer(2, TimeUnit.SECONDS).subscribe(new Observer<Long>() { @Override public void onSubscribe(Disposable disposable) { System.out.println("onSubscribe"); } @Override public void onNext(Long aLong) { System.out.println("onNext: "+aLong); } @Override public void onError(Throwable throwable) { } @Override public void onComplete() { System.out.println("onComplete"); } });