import 'package:flutter/services.dart';
SystemChannels.platform.invokeMethod<void>('SystemNavigator.pop');

監(jiān)聽返回鍵，并關(guān)閉：
return WillPopScope(
onWillPop: () {
SystemChannels.platform.invokeMethod<void>('SystemNavigator.pop');
return Future.value(true);
},
child: Scaffold(
// UI 代碼
)
);