RxJava & RxAndroid简单使用（3）

RxJava的异步机制线程的调度Scheduler，RxJava内部有一个Schedulers类，里面有5种Scheduler类型，1.0里面有Schedulers.immediate( )，而在2.0就去掉了，2.0有个新的类型Schedulers.single()。最常用的就两种：Schedulers.io()和AndroidSchedulers.mainThread()。

Scheduler类型

• Schedulers.io() I/O 操作 内部实现是是用一个无数量上限的线程池

    /**     * Creates and returns a {@link Scheduler} intended for IO-bound work.     * <p>     * The implementation is backed by an {@link Executor} thread-pool that will grow as needed.     * <p>     * This can be used for asynchronously performing blocking IO.     * <p>     * Do not perform computational work on this scheduler. Use {@link #computation()} instead.     * <p>     * Unhandled errors will be delivered to the scheduler Thread's {@link java.lang.Thread.UncaughtExceptionHandler}.     *     * @return a {@link Scheduler} meant for IO-bound work     */    public static Scheduler io() {        return RxJavaPlugins.onIoScheduler(IO);    }

• Schedulers.single() 单线程操作 2.0以上才加的，貌似1.0没有

    /**     * Returns the common, single-thread backed Scheduler instance.     * <p>     * Uses:     * <ul>     * <li>main event loop</li>     * <li>support Schedulers.from(Executor) and from(ExecutorService) with delayed scheduling</li>     * <li>support benchmarks that pipeline data from the main thread to some other thread and     * avoid core-bashing of computation's round-robin nature</li>     * </ul>     * @return a {@link Scheduler} that shares a single backing thread.     * @since 2.0     */    public static Scheduler single() {        return RxJavaPlugins.onSingleScheduler(SINGLE);    }

• Schedulers.immediate( )在当前线程立即开始执行任务 这个是1.0有，2.0没有这个类型了

1.0的immediate()方法的源码这里就不贴出来了

• Schedulers.newThread() 每次都启用新线程，并在新线程执行操作

    /**     * Creates and returns a {@link Scheduler} that creates a new {@link Thread} for      * each unit of work.     * <p>     * Unhandled errors will be delivered to the scheduler      * Thread's {@link java.lang.Thread.UncaughtExceptionHandler}.     *     * @return a {@link Scheduler} that creates new threads     */    public static Scheduler newThread() {        return RxJavaPlugins.onNewThreadScheduler(NEW_THREAD);    }

• Schedulers.trampoline() 当其它排队的任务完成后，在当前线程排队开始执行

    /**     * Creates and returns a {@link Scheduler} that queues work on the current thread      * to be executed after the     * current work completes.     *     * @return a {@link Scheduler} that queues work on the current thread     */    public static Scheduler trampoline() {        return TRAMPOLINE;    }

• Schedulers.computation() 用于计算任务，如事件循环或和回调处理，不要用于IO操作(IO操作请使用Schedulers.io())；默认线程数等于处理器的数量

    /**     * Creates and returns a {@link Scheduler} intended for computational work.     * <p>     * This can be used for event-loops, processing callbacks and other computational work.     * <p>     * Do not perform IO-bound work on this scheduler. Use {@link #io()} instead.     * <p>     * Unhandled errors will be delivered to the scheduler Thread's     * {@link java.lang.Thread.UncaughtExceptionHandler}.     *     * @return a {@link Scheduler} meant for computation-bound work     */    public static Scheduler computation() {        return RxJavaPlugins.onComputationScheduler(COMPUTATION);    }

• Schedulers.from(executor)

    /**     * Converts an {@link Executor} into a new Scheduler instance.     *     * @param executor     *          the executor to wrap     * @return the new Scheduler wrapping the Executor     */    public static Scheduler from(Executor executor) {        return new ExecutorScheduler(executor);    }

Schedulers的简单使用

        Observable.just(1, 2, 3)                .subscribeOn(Schedulers.io())             //订阅事件发生在io线程                .observeOn(AndroidSchedulers.mainThread())//在主线程中观察                .subscribe(new Observer<Integer>() {                    @Override                    public void onSubscribe(Disposable d) {                    }                    @Override                    public void onNext(Integer value) {                    }                    @Override                    public void onError(Throwable e) {                    }                    @Override                    public void onComplete() {                    }                });