基類的popupwindow，帶點擊區域外消失，返回鍵消失

public class BasePopupWindow extends PopupWindow {

    public Context mContext;

    public BasePopupWindow (Context context) {
        super(context);
        this.mContext = context;
         //popWindow彈出可以點擊返回鍵消失
        this.setFocusable(false);
        //設置pop的點擊外面可以消失
        this.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
        // 設置背景顏色變暗
        WindowManager.LayoutParams lp = ((Activity) context).getWindow().getAttributes();
        lp.alpha = 0.4f;
        ((Activity) context).getWindow().setAttributes(lp);
    }

    @Override
    public void dismiss() {
        WindowManager.LayoutParams lp1 = ((Activity) mContext).getWindow().getAttributes();
        lp1.alpha = 1f;
        ((Activity) mContext).getWindow().setAttributes(lp1);
        super.dismiss();
    }
}