Android(安卓)Spinner点击选中Item不再调用onItemSelected方法的方案

Android中使用Spinner有时有二级菜单需要操作，这时选中了某一项，想再点击这一项进入二级菜单重新选择时，onItemSelected方法是不会重新调用的，二级菜单出不来，影响功能。看Spinner源码，只有现在选中的position（或rowId）和点击的position（或rowId）不一样，才会触发onItemSelected回调。

AdapterView.java：

void checkSelectionChanged() {        if ((mSelectedPosition != mOldSelectedPosition) || (mSelectedRowId != mOldSelectedRowId)) {            selectionChanged();            mOldSelectedPosition = mSelectedPosition;            mOldSelectedRowId = mSelectedRowId;        }}void selectionChanged() {        if (mOnItemSelectedListener != null                || AccessibilityManager.getInstance(mContext).isEnabled()) {            if (mInLayout || mBlockLayoutRequests) {                // If we are in a layout traversal, defer notification                // by posting. This ensures that the view tree is                // in a consistent state and is able to accomodate                // new layout or invalidate requests.                if (mSelectionNotifier == null) {                    mSelectionNotifier = new SelectionNotifier();                }                post(mSelectionNotifier);            } else {                fireOnSelected();                performAccessibilityActionsOnSelected();            }        }    }private void fireOnSelected() {        if (mOnItemSelectedListener == null) {            return;        }        final int selection = getSelectedItemPosition();        if (selection >= 0) {            View v = getSelectedView();            mOnItemSelectedListener.onItemSelected(this, v, selection,                    getAdapter().getItemId(selection));        } else {            mOnItemSelectedListener.onNothingSelected(this);        }    }

那么方案就是让点击的position（或mSelectedRowId ）和之前的position（或mSelectedRowId ）不一样即可让回调方法执行。那么拦截onTouch事件，在其中将mOldSelectedPosition或mOldSelectedRowId改为不会和现在点击的一样即可。方法如下：

spinner.setOnTouchListener(new View.OnTouchListener() {            @Override            public boolean onTouch(View v, MotionEvent event) {                try {                    Class<?> clazz = AdapterView.class;                    //Field field = clazz.getDeclaredField("mOldSelectedPosition");                    //field.setAccessible(true);                    //field.setInt(spn,-1);                    Field field = clazz.getDeclaredField("mOldSelectedRowId");                    field.setAccessible(true);                    field.setInt(spn_ps,Integer.MIN_VALUE);                } catch(Exception e){                    e.printStackTrace();                }                return false;            }        });

onTouch返回false，这样事件可以继续传递下去，OnItemSelectedListener得以响应。

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