如何让Flutter Widget在一定时间后(以天为单位)消失？

import 'package:flutter/material.dart';
import 'dart:async';

class DisappearingWidget extends StatefulWidget {
  @override
  _DisappearingWidgetState createState() => _DisappearingWidgetState();
}

class _DisappearingWidgetState extends State<DisappearingWidget> {
  Timer _timer;

  @override
  void initState() {
    super.initState();
    _startTimer();
  }

  void _startTimer() {
    const duration = Duration(days: 1); // 设置消失时间为1天
    _timer = Timer(duration, () {
      setState(() {
        // 在定时器结束后更新状态，触发Widget的重建
      });
    });
  }

  @override
  void dispose() {
    _timer?.cancel(); // 取消定时器，释放资源
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return _timer.isActive ? _buildWidget() : Container(); // 根据定时器是否激活来决定是否显示Widget
  }

  Widget _buildWidget() {
    // 返回需要显示的Widget
    return Container(
      child: Text('这是一个会在一定时间后消失的Widget'),
    );
  }
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('消失Widget示例'),
        ),
        body: Center(
          child: DisappearingWidget(),
        ),
      ),
    );
  }
}