RxAndroid:在Schedulers.io()线程上更改UI

Question

我在IO线程上有简单的工作,正在改变主屏幕壁纸,之后我试图在UI线程上运行一些动画:

     AppObservable.bindFragment(this, Observable.just(0))
       .observeOn(Schedulers.io())
       .subscribe(v -> setWallpaperOnSeparateThread());

private void setWallpaperOnSeparateThread() {
     WallpaperHelper.setBitmapAsWallpaper(photoViewAttacher.getVisibleRectangleBitmap(), getBaseActivity());

     AppObservable.bindFragment(this, Observable.just(0))
       .delay(500, TimeUnit.MILLISECONDS)
       .observeOn(AndroidSchedulers.mainThread())
       .subscribe(integer -> loadFinishAnimationAfterSetWallpaper());
}

但这种方法导致错误: java.lang.IllegalStateException: Observers must subscribe from the main UI thread, but was Thread[RxCachedThreadScheduler-1,5,main]

我试图将第二个Observable改为:

  AppObservable.bindFragment(this, Observable.just(0))
    .delay(2000, TimeUnit.MILLISECONDS)
    .observeOn(Schedulers.io())
    .subscribeOn(AndroidSchedulers.mainThread())
    .subscribe(integer -> loadFinishAnimationAfterSetWallpaper());

但它没有帮助.

Answer 1

AppObservable.bindFragment(this, Observable.just(0)) 抛出异常,因为它没有从主线程中调用

这个代码不是在主线程中调用的,因为你Schedulers.io在这段代码中看到了(见下文),而不是后面的调用AppObservable.bindFragment(this, Observable.just(0))

AppObservable.bindFragment(this, Observable.just(0))
   .observeOn(Schedulers.io())
   .subscribe(v -> setWallpaperOnSeparateThread());

您想在io线程中执行任务,然后在主线程中执行任务.为此,您可以使用一个链接Observable.

AppObservable.bindFragment(this, Observable.just(0))
   .observeOn(Schedulers.io())
   .flatMap(v -> Observable.defer(() -> WallpaperHelper.setBitmapAsWallpaper(photoViewAttacher.getVisibleRectangleBitmap(), getBaseActivity())))
   .delay(500, TimeUnit.MILLISECONDS)
   .observeOn(AndroidSchedulers.mainThread())
   .subscribe(v -> loadFinishAnimationAfterSetWallpaper());

请注意我defer用来表示您的异步任务,Observable但您可以用flatMap呼叫替换doOnNext呼叫.

AppObservable.bindFragment(this, Observable.just(0))
   .observeOn(Schedulers.io())
   .doOnNext(v -> WallpaperHelper.setBitmapAsWallpaper(photoViewAttacher.getVisibleRectangleBitmap(), getBaseActivity()))
   .delay(500, TimeUnit.MILLISECONDS)
   .observeOn(AndroidSchedulers.mainThread())
   .subscribe(v -> loadFinishAnimationAfterSetWallpaper());

Answer 2

实际上observeOn用于subcscriber线程,而subscribeOn用于可观察线程.所以你应该扭转它们

.observeOn(AndroidSchedulers.mainThread())
.subscribeOn(Schedulers.io())