Flutter Dialog 屏蔽返回鍵

使用 WillPopScope + Future.value(false); 屏蔽返回鍵。代碼如下：

showDialog<Null>(
  context: context, // BuildContext對象
 barrierDismissible: false, // 屏蔽點擊對話框外部自動關閉
 builder: (_) => WillPopScope(
 child: AlertDialog(
 content: Text(
 '賬戶登錄信息已過期，是否重新登錄？',
 ),
 actions: <Widget>[
 FlatButton(
 child: buildCommonText(
 content: getResString(context, StringIds.dialog_exit),
 fontSize: SIZE14,
 color: color_888,
 ),
 onPressed: () => exitApp(),
 ),
 FlatButton(
 child: buildCommonText(
 content: getResString(context, StringIds.dialog_relogin),
 fontSize: SIZE14,
 fontWeight: FontWeight.w600,
 color: color_FF664B,
 ),
 onPressed: () => super.exitLogin(),
 ),
 ],
 ),
 onWillPop: () async {
 return Future.value(false);
 },
 ),
);