Question

我在IO线程上做了简单的工作，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());
}

但这种方法会导致错误： 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))抛出一个异常，因为它没有从主线程中调用

此代码未在主线程中调用，因为您在此代码Schedulers.io中观察到（见下文），而不是后者调用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Observable链接来电。

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，我使用defer将您的异步任务表示为Observable，但您可以将flatMap来电替换为doOnNext来电。

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())

RxAndroid：在Schedulers.io（）线程上更改UI

2 个答案: