ProgressDialog.java 文件源码

public void onWindowFocusChanged(boolean hasFocus) {

        if (customProgressDialog == null) {
            return;
        }

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