//这是show一个PopupWindow 

  PopupWindow mPopupWindow;

    public void showPopupWindow() {

LayoutInflater mLayoutInflater = (LayoutInflater) this.getSystemService(LAYOUT_INFLATER_SERVICE);

View music_popunwindwow = mLayoutInflater.inflate(R.layout.portal_select_layout, null);

ListView portal_select_listView = (ListView) music_popunwindwow.findViewById(R.id.portal_select_listView);

ArrayList androi = new ArrayList();

for (int i = 0; i < 10; i++) {

androi.add(""+i);}

portal_select_listView.setAdapter( new ArrayAdapter(this,android.R.layout.simple_spinner_dropdown_item,androi));

//popwindow的宽度和按钮的宽度相同都是230

mPopupWindow = new PopupWindow(music_popunwindwow,230, LayoutParams.WRAP_CONTENT);

mPopupWindow.setFocusable(true);

mPopupWindow.setOutsideTouchable(true);

mPopupWindow.update();

//位置在R.id.button的正下方

mPopupWindow.showAsDropDown(findViewById(R.id.button), 0,5);

}