public class ObservableScrollView extends ScrollView {    public ObservableScrollView(Context context) {        super(context);    }    public ObservableScrollView(Context context, AttributeSet attrs) {        super(context, attrs);    }    public ObservableScrollView(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);    }    public interface OnScrollChangedListener {        public void onScrollChanged(int x, int y, int oldX, int oldY);    }    private OnScrollChangedListener onScrollChangedListener;    public void setOnScrollListener(OnScrollChangedListener onScrollChangedListener) {        this.onScrollChangedListener = onScrollChangedListener;    }    @Override    protected void onScrollChanged(int x, int y, int oldX, int oldY) {        super.onScrollChanged(x, y, oldX, oldY);        if (onScrollChangedListener != null) {            onScrollChangedListener.onScrollChanged(x, y, oldX, oldY);        }    }}

 

参考自：http://stormzhang.com/android/2015/02/01/android-observable-scrollview/