Spinner只提供展开的监听，并未提供收起的监听

有时候需要监听Spinner列表的收起，比如根据展开收起的状态，改变右边显示的arrow图标的方向

我们可以通过自定义Spinner来监听列表的展开和收起

自定义Spinner

public class CustomSpinner extends Spinner {private OnSpinnerEventsListener mListener;private boolean mOpenInitiated = false;public CustomSpinner(Context context, AttributeSet attrs, int defStyleAttr, int mode) {super(context, attrs, defStyleAttr, mode);}public CustomSpinner(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);}public CustomSpinner(Context context, AttributeSet attrs) {super(context, attrs);}public CustomSpinner(Context context, int mode) {super(context, mode);}public CustomSpinner(Context context) {super(context);}public interface OnSpinnerEventsListener {void onSpinnerOpened();void onSpinnerClosed();}public void setSpinnerEventsListener(OnSpinnerEventsListener onSpinnerEventsListener) {mListener = onSpinnerEventsListener;}@Overridepublic boolean performClick() {mOpenInitiated = true;if (mListener != null) {mListener.onSpinnerOpened();}return super.performClick();}public void performClosedEvent() {mOpenInitiated = false;if (mListener != null) {mListener.onSpinnerClosed();}}public boolean hasBeenOpened() {return mOpenInitiated;}@Overridepublic void onWindowFocusChanged(boolean hasWindowFocus) {super.onWindowFocusChanged(hasWindowFocus);if (hasBeenOpened() && hasWindowFocus) {performClosedEvent();}}
}

使用

customSpinner.setSpinnerEventsListener(new CustomSpinner.OnSpinnerEventsListener() {@Overridepublic void onSpinnerOpened() {// 展开}@Overridepublic void onSpinnerClosed() {// 收起}
});