ShowProgressDialog.java 文件源码

public void onWindowFocusChanged(boolean hasFocus){
    if (progressDialog == null){
        return;
    }

    ImageView imageView = (ImageView) progressDialog.findViewById(R.id.loadingImageView);
    AnimationDrawable animationDrawable = (AnimationDrawable) imageView.getBackground();
    animationDrawable.start();
}