问题在于，context用来显示的BottomSheet不是context的Scaffold。你可以通过使用GlobalKey或将其包装GestureDetector在Builder小部件中来解决此问题，以便为你提供context包含的引用Scaffold。

这是一个使用GlobalKey的状态的示例Scaffold：

// created the ScaffoldState key    
final scaffoldState = GlobalKey<ScaffoldState>();
    
    class MyWidget extends StatelessWidget {
      void _showSheet() {
        // Show BottomSheet here using the Scaffold state instead ot«f the Scaffold context
        scaffoldState.currentState
            .showBottomSheet((context) => Container(color: Colors.red));
      }
    
      @override
      Widget build(BuildContext context) {
        return Scaffold(
            key: scaffoldState,
            appBar: AppBar(
              title: Text("Calendar"),
            ),
            body: SafeArea(child: GestureDetector(onTap: () {
              //getting exception here
              _showSheet();
            })));
      }
    }