PopupWindow--点击ListView的Item，popupwindow出现在点击item下方

1.原理

ListView的 public void onItemClick(AdapterView<?> adapterView, View view, int position, long l)的view是所点击的Item的对应View，通过popupwindow.showAsDropDown(anchor);通过anchor的位置显示popupwindow

代码如下

<pre name="code" class="java">/**     * show the reason why don't supply the dish by floatview     *     * @param anchor     * @param item     * @param curViewY     */    private void showReason(View anchor, ConsignorDataRangeTimeItem item, int curViewY) {        PopupView popup = new PopupView(this);        View view = View.inflate(this, R.layout.consignor_reason_notsupply, null);                popup.initView(this, view, popup.screenWidth / 2, WindowManager.LayoutParams.WRAP_CONTENT);        if(popup.needReverse(anchor,curViewY)){            view.setBackgroundResource(R.drawable.popup_view_bg_reverse);        }        popup.showView(anchor, 0, 0);    }    @Override    public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {        int id = adapterView.getId();        switch (id) {            case R.id.consignor_data_range_list:                ConsignorDataRangeTimeItem item = list.get(position);                if (item.getNotCount() == 0)                    return;                View anchor = view.findViewById(R.id.consignor_data_time_range__item_dropdown);                int[]scr=new int[2];                view.getLocationOnScreen(scr);//获取view的绝对位置                showReason(anchor, item, scr[1]);        }    }    public static class PopupView {        private final Context mContext;        private PopupWindow mPopup;        private WindowManager wm;        public int screenWidth;        public int screenHeight;        public PopupView(Context context) {            mContext = context;        }        /**         * reset the popupwindow         */        public void reset() {            mPopup.dismiss();            mPopup = null;        }        public void setScreen() {            wm = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);            //设置LayoutParams(全局变量）相关参数            WindowManager.LayoutParams params = new WindowManager.LayoutParams();            //获取屏幕尺寸            //Display display=wm.getDefaultDisplay();            DisplayMetrics dm = new DisplayMetrics();            wm.getDefaultDisplay().getMetrics(dm);            screenWidth = dm.widthPixels;            screenHeight = dm.heightPixels;        }        /**         * init the popupview         *         * @param context         * @param view    the view add to popup view         */        protected void initView(Context context, View view, int width, int height) {            // TODO Auto-generated method stub            if (width == 0 || height == 0) {                setScreen();                width = screenWidth / 2;                height = WindowManager.LayoutParams.WRAP_CONTENT;            }            mPopup = new PopupWindow(view, width, height);        /*设置背景显示 */            //menuView.setBackgroundResource(R.color.transparent);            //设置触摸外面时消失            mPopup.setOutsideTouchable(true);            //设置系统动画            mPopup.setAnimationStyle(android.R.style.Animation_Dialog);            mPopup.setTouchable(true);            mPopup.setBackgroundDrawable(new BitmapDrawable());            mPopup.update();            //设置了可获得焦点才能让Popu盘Window中的控件获取相应            mPopup.setFocusable(true);        }        /**         * show popup view         *         * @param anchor  a parent view to get the getWindowToken() token from         * @param offsetX         * @param offsetY         */        public void showView(View anchor, int offsetX, int offsetY) {            // TODO Auto-generated method stub            mPopup.showAsDropDown(anchor);            //mPopup.showAtLocation(anchor, Gravity.RIGHT|Gravity.TOP, offsetX, offsetY);        }        /**         * hide the popup view         */        public void hideView() {            if (mPopup.isShowing())                mPopup.dismiss();        }        /**         *         * @param anchor         * @param curViewY         * @return if curViewY>=maxHeight return true;         */        public boolean needReverse(View anchor, int curViewY) {            int maxHeight=   mPopup.getMaxAvailableHeight(anchor);            return curViewY>=maxHeight;        }    }