Flutter如何跨dart文件导入调用函数及AdvancedDrawer跨页控制

你的问题核心是两个点：

1. _advancedDrawerController、_handleMenuButtonPressed 都是_DashboardState的私有成员（名称带下划线），跨类/跨文件默认无法直接访问
2. 你没有把父组件Dashboard的相关实例和方法通过参数传递给子组件HomePage，导致HomePage里调用的变量不存在

步骤1：修改HomePage，新增接收参数的属性 #

给HomePage增加两个必填参数，分别接收抽屉控制器实例和菜单按钮点击回调：

class HomePage extends StatefulWidget {
  const HomePage({
    Key? key,
    required this.onMenuTap,
    required this.drawerController,
  }) : super(key: key);

  // 菜单按钮点击回调
  final VoidCallback onMenuTap;
  // 抽屉控制器实例
  final AdvancedDrawerController drawerController;

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SingleChildScrollView(
        child: SafeArea(
          child: Column(
            children: <Widget>[
              Padding(
                padding: const EdgeInsets.all(12.0),
                child: Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: <Widget>[
                    IconButton(
                      // 调用父组件传递的回调
                      onPressed: widget.onMenuTap,
                      icon: ValueListenableBuilder<AdvancedDrawerValue>(
                        // 绑定父组件传递的控制器
                        valueListenable: widget.drawerController,
                        builder: (_, value, __) {
                          return AnimatedSwitcher(
                            duration: const Duration(milliseconds: 250),
                            child: Icon(
                              value.visible ? Icons.clear : Icons.menu,
                              key: ValueKey<bool>(value.visible),
                            ),
                          );
                        },
                      ),
                    ),
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

步骤2：修改Dashboard，给HomePage传递参数 #

修改Dashboard中PageView的children部分，把当前State的抽屉控制器和开关方法传给每个HomePage实例即可：

body: PageView(
  controller: _pageController,
  children: <Widget>[
    HomePage(onMenuTap: _handleMenuButtonPressed, drawerController: _advancedDrawerController),
    HomePage(onMenuTap: _handleMenuButtonPressed, drawerController: _advancedDrawerController),
    HomePage(onMenuTap: _handleMenuButtonPressed, drawerController: _advancedDrawerController),
    HomePage(onMenuTap: _handleMenuButtonPressed, drawerController: _advancedDrawerController),
    HomePage(onMenuTap: _handleMenuButtonPressed, drawerController: _advancedDrawerController),
  ],
  onPageChanged: (page) {
    setState(() {
      _selectedIndex = page;
    });
  },
),

可选优化 #

如果两个类不在同一个.dart文件里，你需要把AdvancedDrawerController的导入语句也加到HomePage对应的文件里，避免类型未定义的报错。
如果后续你的组件层级更深、传参路径太长，也可以用Provider、GetX等状态管理方案全局存储抽屉控制器，就不用逐层传参，当前场景用构造函数传参是最简单、性能最优的方案。

内容的提问来源于stack exchange，提问作者Asver Seb