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flutter基础2

时间：2023-03-31 14:34:45浏览次数：40  
标签：const Text 基础 dart context child import flutter

1.有状态组件StatefulWidget

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        theme: ThemeData(primarySwatch: Colors.blue), home: const HomePage());
  }
}

//  有状态组件
class HomePage extends StatefulWidget {
  const HomePage({super.key});

  @override
  //实现抽象方法
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  int _num = 0;
  final List<String> list = [];
  @override
  Widget build(BuildContext context) {
    print(_num);
    return Scaffold(
      appBar: AppBar(
        title: const Text("flutter app"),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              "$_num",
              style: Theme.of(context).textTheme.headlineLarge,
            ),
            const SizedBox(
              height: 40,
            ),
            ElevatedButton(
                onPressed: () {
                  setState(() {
                    _num++;
                  });
                },
                child: const Text("增加"))
          ],
        ),
      ),
      //浮动的按钮
      floatingActionButton: FloatingActionButton(
        onPressed: () {
        //通过setState来更新视图
setState(() { _num++; }); },
 child: const Icon(Icons.add), ), ); } }

 2.自定义底部导航bottomNavigationBar

import 'package:flutter/material.dart';
import 'package:flutter02/pages/tabs/cate.dart';
import 'package:flutter02/pages/tabs/message.dart';
import 'package:flutter02/pages/tabs/setting.dart';
import 'package:flutter02/pages/tabs/home.dart';
import 'package:flutter02/pages/tabs/user.dart';

class Tabs extends StatefulWidget {
  const Tabs({super.key});

  @override
  State<Tabs> createState() => _TabsState();
}

class _TabsState extends State<Tabs> {
  int _currentIndex = 0;
  List list = const [
    HomePage(),
    CatePage(),
    MessagePage(),
    SettingPage(),
    UserPage(),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("flutter app"),
      ),
      body: list[_currentIndex],
      bottomNavigationBar: BottomNavigationBar(
          iconSize: 40, //底部菜单大小
          currentIndex: _currentIndex, //当前的索引
          fixedColor: Colors.red, //选择的颜色
          type: BottomNavigationBarType.fixed, //底部有4个或4个以上菜单需要配置
          onTap: (index) => {
                setState(
                  () {
                    _currentIndex = index;
                  },
                )
              },
          items: const [
            BottomNavigationBarItem(icon: Icon(Icons.home), label: "首页"),
            BottomNavigationBarItem(
                icon: Icon(
                  Icons.category,
                ),
                label: "分类"),
            BottomNavigationBarItem(
                icon: Icon(
                  Icons.message_rounded,
                ),
                label: "消息"),
            BottomNavigationBarItem(
                icon: Icon(
                  Icons.settings,
                ),
                label: "设置"),
            BottomNavigationBarItem(
                icon: Icon(
                  Icons.person_2,
                ),
                label: "用户"),
          ]),
      floatingActionButton: Container(
        padding: const EdgeInsets.all(8),
        margin: const EdgeInsets.only(top: 32),
        height: 60,
        width: 60,
        decoration: BoxDecoration(
            color: Colors.white, borderRadius: BorderRadius.circular(30)),
        child: FloatingActionButton(
          onPressed: () {
            setState(() {
              _currentIndex = 2;
            });
          },
          backgroundColor: _currentIndex == 2 ? Colors.yellow : Colors.blue,
          child: const Icon(Icons.add),
        ),
      ),
      floatingActionButtonLocation:
          FloatingActionButtonLocation.centerDocked, //调整浮动按钮的位置
    );
  }
}

 3.侧边栏组件

import 'package:flutter/material.dart';
import 'package:flutter02/pages/tabs/cate.dart';
import 'package:flutter02/pages/tabs/message.dart';
import 'package:flutter02/pages/tabs/setting.dart';
import 'package:flutter02/pages/tabs/home.dart';
import 'package:flutter02/pages/tabs/user.dart';

class Tabs extends StatefulWidget {
  const Tabs({super.key});

  @override
  State<Tabs> createState() => _TabsState();
}

class _TabsState extends State<Tabs> {
  int _currentIndex = 0;
  List list = const [
    HomePage(),
    CatePage(),
    MessagePage(),
    SettingPage(),
    UserPage(),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("flutter app"),
      ),
      body: list[_currentIndex],
      drawer: const Drawer(
          //配置侧边栏
          child: Column(
        children: [
          Row(
            children: [
              Expanded(
                  // UserAccountsDrawerHeader
                  flex: 1,
                  child: UserAccountsDrawerHeader(
                    //使用内置配置
                    currentAccountPicture: CircleAvatar(
                      backgroundImage: NetworkImage(
                          "https://p1.itc.cn/q_70/images03/20210817/1203acff86d74d7e8cd644d05d3e5525.jpeg"),
                    ),
                    accountName: Text("张三"), //用户名
                    accountEmail: Text("igqq.com"), //邮箱
                    decoration: BoxDecoration(
                        image: DecorationImage(
                            fit: BoxFit.cover,
                            image: NetworkImage(
                                "https://pic.616pic.com/bg_w1180/00/23/16/1KY6cAGuC9.jpg"))),
                  ))
            ],
          ),
          ListTile(
            leading: CircleAvatar(
              child: Icon(Icons.people),
            ),
            title: Text('个人中心'),
          ),
          Divider(),
          ListTile(
            leading: Icon(Icons.settings),
            title: Text('系统设置'),
          ),
          Divider(),
        ],
      )),
      endDrawer: Drawer(child: Text("又称侧边栏")),
      bottomNavigationBar: BottomNavigationBar(
          iconSize: 40, //底部菜单大小
          currentIndex: _currentIndex, //当前的索引
          fixedColor: Colors.red, //选择的颜色
          type: BottomNavigationBarType.fixed, //底部有4个或4个以上菜单需要配置
          onTap: (index) => {
                setState(
                  () {
                    _currentIndex = index;
                  },
                )
              },
          items: const [
            BottomNavigationBarItem(icon: Icon(Icons.home), label: "首页"),
            BottomNavigationBarItem(
                icon: Icon(
                  Icons.category,
                ),
                label: "分类"),
            BottomNavigationBarItem(
                icon: Icon(
                  Icons.message_rounded,
                ),
                label: "消息"),
            BottomNavigationBarItem(
                icon: Icon(
                  Icons.settings,
                ),
                label: "设置"),
            BottomNavigationBarItem(
                icon: Icon(
                  Icons.person_2,
                ),
                label: "用户"),
          ]),
      floatingActionButton: Container(
        padding: const EdgeInsets.all(8),
        margin: const EdgeInsets.only(top: 32),
        height: 60,
        width: 60,
        decoration: BoxDecoration(
            color: Colors.white, borderRadius: BorderRadius.circular(30)),
        child: FloatingActionButton(
          onPressed: () {
            setState(() {
              _currentIndex = 2;
            });
          },
          backgroundColor: _currentIndex == 2 ? Colors.yellow : Colors.blue,
          child: const Icon(Icons.add),
        ),
      ),
      floatingActionButtonLocation:
          FloatingActionButtonLocation.centerDocked, //调整浮动按钮的位置
    );
  }
}

// DrawerHeader(

//                     //配置侧边栏顶部
//                     decoration: BoxDecoration(
//                         // color: Colors.yellow,
//                         image: DecorationImage(
//                             fit: BoxFit.cover,
//                             image: NetworkImage(
//                                 "https://pic.616pic.com/bg_w1180/00/23/16/1KY6cAGuC9.jpg"))),
//                     child: Column(
//                       children: [
//                         ListTile(
//                           leading: CircleAvatar(
//                             backgroundImage: NetworkImage(
//                                 "https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fc-ssl.duitang.com%2Fuploads%2Fitem%2F202008%2F13%2F20200813151914_vk2eR.thumb.1000_0.jpeg&refer=http%3A%2F%2Fc-ssl.duitang.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=auto?sec=1680700489&t=219227023128b19f44b83679a2fd3074"),
//                           ),
//                           title: Text(
//                             '张三',
//                             style: TextStyle(color: Colors.white),
//                           ),
//                         ),
//                         ListTile(
//                           title: Text("邮箱：xxxqq.com"),
//                         ),
//                       ],
//                     )),

 

4.头部TabBar组件

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        debugShowCheckedModeBanner: false, //去掉debug
        title: "flutter app",
        theme: ThemeData(primarySwatch: Colors.blue),
        home: const HomePage());
  }
}

class HomePage extends StatefulWidget {
  const HomePage({super.key});

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

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  late TabController _tabController;
  @override
  //生命周期函数，组件初始化时触发
  void initState() {
    // TODO: implement initState
    super.initState();
    _tabController = TabController(length: 3, vsync: this); //指定长度
    //监听_tabController的改变事件,获取索引值
    _tabController.addListener(() {
      // print(_tabController.index);//回触发两次
      // if (_tabController.animation!.value == _tabController.index) {
      //   print(_tabController.index);
      // }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
          leading: IconButton(
            //配置导航左侧图标
            icon: const Icon(Icons.menu),
            onPressed: () {
              print("asdsdfds");
            },
          ),
          backgroundColor: Colors.yellow, //背景颜色
          actions: [
            //右侧的图标，可以配置多个
            IconButton(onPressed: () {}, icon: const Icon(Icons.search_sharp))
          ],
          bottom: TabBar(
              controller: _tabController,
              indicatorColor: Colors.red, //指示器的颜色
              indicatorWeight: 3, //指示器的高度
              indicatorPadding: const EdgeInsets.all(5), //指示器的边距
              labelColor: Colors.blue, //选中的颜色
              unselectedLabelColor: Colors.green, //未选择的颜色
              labelStyle: const TextStyle(fontSize: 16), //设置样式
              onTap: (index) {
                //只能监听点击事件
                print(index);
              },
              tabs: const [
                //配置tabs
                Tab(
                  child: Text("关注"),
                ),
                Tab(
                  child: Text("热门"),
                ),
                Tab(
                  child: Text("视频"),
                ),
              ]),
          title: const Text("FLutter app")),
      body: TabBarView(controller: _tabController, children: const [
        //与TabBar对应
        Text("我是关注"),
        Text("我是热门"),
        Text("我是视频"),
      ]),
    );
  }
}

 5.路由

5.1基本路由

import 'package:flutter/material.dart';
import '../search.dart';
import '../form.dart';

class HomePage extends StatefulWidget {
  const HomePage({super.key});

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

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        children: [
          ElevatedButton(
              onPressed: () {
                Navigator.of(context) //路由跳转页面
                    .push(MaterialPageRoute(builder: (BuildContext context) {
                  return const SearchPage();
                }));
              },
              child: const Text("跳转搜索")),
          ElevatedButton(
              onPressed: () {
                Navigator.of(context) //跳转传值
                    .push(MaterialPageRoute(builder: (BuildContext context) {
                  return const FromPage(title: "表单页面", id: 13);
                }));
              },
              child: const Text("跳转表单"))
        ],
      ),
    );
  }
}

import 'package:flutter/material.dart';

class SearchPage extends StatefulWidget {
  const SearchPage({super.key});

  @override
  State<SearchPage> createState() => _SearchPageState();
}

class _SearchPageState extends State<SearchPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          Navigator.pop(context); //返回到上一页
        },
        child: const Icon(Icons.home),
      ),
      appBar: AppBar(
        title: const Text("搜索页面"),
      ),
      body: const Center(child: Text("搜索页面")),
    );
  }
}

//接受传递的参数
import 'dart:ffi';
import 'package:flutter/material.dart';
class FromPage extends StatefulWidget {   final String title; //接受路由传参   final int id;   const FromPage({super.key, this.title = "新闻", required this.id});
  @override   State<FromPage> createState() => _FromPageState(); }
class _FromPageState extends State<FromPage> {   @override   void initState() {     // TODO: implement initState     super.initState();     print(widget.id);   }
  @override   Widget build(BuildContext context) {     return Scaffold(       appBar: AppBar(         title: Text("表单页面"),       ),       body: Text(widget.title), //接受路由传参     );   } } 
 

 5.2命名路由

//路由配置route.dart文件
import 'package:flutter/material.dart';
import 'package:flutter02/pages/mine.dart';

import 'package:flutter02/pages/news.dart';
import 'package:flutter02/pages/search.dart';
import 'package:flutter02/pages/shop.dart';

//定义命名路由
Map routes = {
  "/": (context) => const NewPage(),
  "/shop": (context) => const ShopPage(),
  "/search": (context) => const SearchPage(),
  "/mine": (context, {arguments}) => MinePage(arguments: arguments),
};

// 路由配置，跳转路由时执行,全局的路由跳转前置处理逻辑。
var onGenerateRoute = (RouteSettings settings) {
  final String? name = settings.name;
  final Function? pageContentBuilder = routes[name];
  if (pageContentBuilder != null) {
    if (settings.arguments != null) {
      final Route route = MaterialPageRoute(
          builder: (context) =>
              pageContentBuilder(context, arguments: settings.arguments));
      return route;
    } else {
      final Route route =
          MaterialPageRoute(builder: (context) => pageContentBuilder(context));
      return route;
    }
  } else {
    return null;
  }
};


//入口文件main.dart
import 'package:flutter/material.dart';
import 'package:flutter02/pages/tabs.dart';
import './routers/route.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false, //去掉debug
      title: "flutter app",
      theme: ThemeData(primarySwatch: Colors.blue),
      initialRoute: "/new", //初始化路由
      onGenerateRoute: onGenerateRoute, //路由配置，跳转路由时执行
    );
  }
}


//路由传参文件
import 'package:flutter/material.dart';

class NewPage extends StatefulWidget {
  const NewPage({
    super.key,
  });

  @override
  State<NewPage> createState() => _NewPageState();
}

class _NewPageState extends State<NewPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("新闻页面"),
        ),
        body: Column(
          children: [
            ElevatedButton(
                onPressed: () {
                  Navigator.pushNamed(context, "/shop"); //命名路由跳转
                },
                child: const Text("跳转购物页面")),
            ElevatedButton(
                onPressed: () {
                  Navigator.pushNamed(context, "/mine",
                      arguments: {"title": "我是命名路由", "id": 20}); //命名路由跳转传值
                },
                child: const Text("跳转我的页面")),
          ],
        )
        //接受路由传参
        );
  }
}

//路由接受参数文件
import 'package:flutter/material.dart';

class MinePage extends StatefulWidget {
  final Map arguments;
  const MinePage({super.key, required this.arguments});

  @override
  State<MinePage> createState() => _MinePageState();
}

class _MinePageState extends State<MinePage> {
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    print(widget.arguments);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("我的页面"),
      ),
      body: const Text("我的页面"), //接受路由传参
    );
  }
}

 5.3 路由替换

//main.dart入口文件
import 'package:flutter/material.dart';
import 'package:flutter02/pages/tabs.dart';
import './routers/route.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false, //去掉debug
      title: "flutter app",
      theme: ThemeData(primarySwatch: Colors.blue),
      initialRoute: "/", //初始化路由
      onGenerateRoute: onGenerateRoute, //路由配置，跳转路由时执行
    );
  }
}


//路由配置文件
// import 'package:flutter/material.dart';
//配置ios风格步骤
//1.删除material.dart 引入cupertino.dart 将MaterialPageRoute替换成CupertinoPageRoute
import 'package:flutter/cupertino.dart';

import 'package:flutter02/pages/mine.dart';

import 'package:flutter02/pages/news.dart';
import 'package:flutter02/pages/search.dart';
import 'package:flutter02/pages/shop.dart';
import 'package:flutter02/pages/user/enter.dart';

import 'package:flutter02/pages/user/login.dart';
import 'package:flutter02/pages/user/register1.dart';
import 'package:flutter02/pages/user/register2.dart';
import 'package:flutter02/pages/user/register3.dart';

//定义命名路由
Map routes = {
  // "/": (context) => const NewPage(),//根页面
  "/": (context) => const EnterPage(),
  "/shop": (context) => const ShopPage(),
  "/search": (context) => const SearchPage(),
  "/mine": (context, {arguments}) => MinePage(arguments: arguments),
  "/login": (context) => const LoginPage(),
  "/register1": (context) => const Register1(),
  "/register2": (context) => const Register2(),
  "/register3": (context) => const Register3(),
};

// 路由配置，跳转路由时执行

var onGenerateRoute = (RouteSettings settings) {
  final String? name = settings.name;
  final Function? pageContentBuilder = routes[name];
  if (pageContentBuilder != null) {
    if (settings.arguments != null) {
      final Route route = CupertinoPageRoute(
          builder: (context) =>
              pageContentBuilder(context, arguments: settings.arguments));
      return route;
    } else {
      final Route route =
          CupertinoPageRoute(builder: (context) => pageContentBuilder(context));
      return route;
    }
  } else {
    return null;
  }
};


//根页面
import 'package:flutter/material.dart';

class EnterPage extends StatefulWidget {
  const EnterPage({super.key});

  @override
  State<EnterPage> createState() => _EnterPageState();
}

class _EnterPageState extends State<EnterPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("登录入口页面"),
      ),
      body: Column(
        children: [
          Center(
            child: ElevatedButton(
                onPressed: () {
                  Navigator.pushNamed(context, "/login"); //命名路由跳转
                },
                child: const Text("登录")),
          ),
          Center(
            child: ElevatedButton(
                onPressed: () {
                  Navigator.pushNamed(context, "/register1"); //命名路由跳转
                },
                child: const Text("注册1")),
          ),
        ],
      ),
    );
  }
}

//登录页面
import 'package:flutter/material.dart';

class LoginPage extends StatefulWidget {
  const LoginPage({super.key});

  @override
  State<LoginPage> createState() => _LoginPageState();
}

class _LoginPageState extends State<LoginPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text("登录页面"),
        ),
        body: Center(
            child: ElevatedButton(
                onPressed: () {
                  Navigator.of(context).pop();
                },
                child: const Text("登录"))) //接受路由传参
        );
  }
}


//注册页面1
import 'package:flutter/material.dart';

class Register1 extends StatefulWidget {
  const Register1({super.key});

  @override
  State<Register1> createState() => _Register1State();
}

class _Register1State extends State<Register1> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text("注册第一步"),
        ),
        body: Center(
            child: ElevatedButton(
                onPressed: () {
                  Navigator.pushNamed(context, "/register2");
                },
                child: const Text("下一步"))) //接受路由传参
        );
  }
}

//注册2
import 'package:flutter/material.dart';

class Register2 extends StatefulWidget {
  const Register2({super.key});

  @override
  State<Register2> createState() => _Register2State();
}

class _Register2State extends State<Register2> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text("注册第二步"),
        ),
        body: Center(
            child: ElevatedButton(
                onPressed: () {
                  // Navigator.pushNamed(context, "/register3");
                  //替换路由，返回时直接到第一步
                  Navigator.of(context).pushReplacementNamed("/register3");
                },
                child: const Text("下一步"))) //接受路由传参
        );
  }
}

//注册3
import 'package:flutter/material.dart';
import 'package:flutter02/pages/user/enter.dart';

class Register3 extends StatefulWidget {
  const Register3({super.key});

  @override
  State<Register3> createState() => _Register3State();
}

class _Register3State extends State<Register3> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text("注册第三步"),
        ),
        body: Center(
            child: ElevatedButton(
                onPressed: () {
                  // Navigator.pushNamed(context, "/");
                  //跳转到根页面
                  Navigator.of(context).pushAndRemoveUntil(
                      MaterialPageRoute(
                          builder: (context) => const EnterPage()),
                      (route) => false);
                },
                child: const Text("完成注册"))) //接受路由传参
        );
  }
}

 6.内置弹框组件dialog以及自定义弹框

import 'package:fluttertoast/fluttertoast.dart';
import './myDialog.dart';

import 'package:flutter/material.dart';

class DialogPage extends StatefulWidget {
  const DialogPage({super.key});

  @override
  State<DialogPage> createState() => _DialogPageState();
}

class _DialogPageState extends State<DialogPage> {
  late bool result;
  late int value;
  void _alertDialog() async {
    result = await showDialog(
        //获取对话框 数据
        context: context,
        builder: (context) {
          return AlertDialog(
            title: const Text("提示"),
            content: const Text("您确定要删除当前文件吗?"),
            actions: <Widget>[
              TextButton(
                child: const Text("取消"),
                onPressed: () => Navigator.of(context).pop(), //关闭对话框
              ),
              TextButton(
                child: const Text("确认"),
                onPressed: () {
                  // ... 执行删除操作
                  Navigator.of(context).pop(true); //关闭对话框
                },
              ),
            ],
          );
        });
    print(result);
  }

//选择弹框
  void _selectDialog() async {
    value = await showDialog(
        barrierDismissible: false, //点击遮挡层弹框关闭控制
        context: context,
        builder: (context) {
          return SimpleDialog(title: const Text('请选择语言'), children: [
            SimpleDialogOption(
              onPressed: () {
                // 返回1
                Navigator.pop(context, 1);
              },
              child: const Padding(
                padding: EdgeInsets.symmetric(vertical: 6),
                child: Text('中文简体'),
              ),
            ),
            SimpleDialogOption(
              onPressed: () {
                // 返回1
                Navigator.pop(context, 2);
              },
              child: const Padding(
                padding: EdgeInsets.symmetric(vertical: 6),
                child: Text('美式英语'),
              ),
            ),
          ]);
        });
    print(value);
  }

//底部弹框
  void _showBottomSheetDialog() async {
    var result = await showModalBottomSheet(
        context: context,
        builder: (context) {
          return SizedBox(
            height: 280,
            child: Column(children: [
              ListTile(
                title: const Text("取消"),
                onTap: () {
                  Navigator.of(context).pop(1);
                },
              ),
              const Divider(),
              ListTile(
                title: const Text("收藏"),
                onTap: () {
                  Navigator.of(context).pop(2);
                },
              ),
              const Divider(),
              ListTile(
                title: const Text("分享"),
                onTap: () {
                  Navigator.of(context).pop(3);
                },
              ),
              const Divider(),
            ]),
          );
        });
    print(result);
  }

//toast弹窗使用第三方插件
  void _toast() {
    Fluttertoast.showToast(
        msg: "提示信息",
        toastLength: Toast.LENGTH_LONG, //设置弹窗消失的时间针对android
        gravity: ToastGravity.CENTER,
        timeInSecForIosWeb: 2, //设置弹窗消失的时间ios
        backgroundColor: Colors.black,
        textColor: Colors.white,
        fontSize: 16.0);
  }

//自定义dialog
  void _myDialog() {
    //需要包裹在showDialog组件中
    showDialog(
        context: context,
        builder: (context) {
          return MyDialog(
            title: "提示！",
            content: "我是一段提示信息",
            onTap: () {
              Navigator.pop(context);
            },
          );
        });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("弹窗页面"),
      ),
      body: Column(children: [
        Center(
          child: ElevatedButton(
              onPressed: _alertDialog, child: const Text("打开对话框")),
        ),
        const SizedBox(height: 20),
        Center(
          child: ElevatedButton(
              onPressed: _selectDialog, child: const Text("打开选择对话框")),
        ),
        const SizedBox(height: 20),
        Center(
          child: ElevatedButton(
              onPressed: _showBottomSheetDialog, child: const Text("打开底部对话框")),
        ),
        const SizedBox(height: 20),
        Center(
          child:
              ElevatedButton(onPressed: _toast, child: const Text("toast弹框")),
        ),
        const SizedBox(height: 20),
        Center(
          child: ElevatedButton(
              onPressed: _myDialog, child: const Text("自定义dialog")),
        ),
      ]), //接受路由传参
    );
  }
}


//自定义弹框
import 'package:flutter/material.dart';

//自定义dialog需要继承Dialog类
class MyDialog extends Dialog {
  final String title;
  final String content;
  final Function()? onTap;
  const MyDialog(
      {super.key, required this.title, required this.content, this.onTap});

  // 实现类中的方法
  @override
  Widget build(BuildContext context) {
    return Material(
      type: MaterialType.transparency, //设置透明度
      child: Center(
          //要用center组件包裹，不然会全屏
          child: Container(
        height: 200,
        width: 260,
        color: Colors.white,
        child: Column(children: [
          Padding(
            padding: EdgeInsets.all(5),
            child: Stack(children: [
              Align(
                alignment: Alignment.centerLeft,
                child: Text(
                  title,
                  style: TextStyle(fontSize: 18),
                ),
              ),
              Align(
                alignment: Alignment.centerRight,
                child: InkWell(
                  //套InkWell组件给元素添加点击事件
                  onTap: onTap,
                  child: const Icon(Icons.close),
                ),
              )
            ]),
          ),
          const Divider(),
          Container(
            padding: const EdgeInsets.all(10),
            child: Text(content),
          )
        ]),
      )),
    );
  }
}

 7.页面切换组件pageView及轮播组件的封装

7.1 pageView组件

import 'package:flutter/material.dart';

class PageViewPage extends StatefulWidget {
  const PageViewPage({super.key});

  @override
  State<PageViewPage> createState() => _PageViewPageState();
}

class _PageViewPageState extends State<PageViewPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("title")),
      body: PageView(
          scrollDirection: Axis.vertical, //配置滑动的方位
          onPageChanged: (index) {
            print(index);
          },
          children: [
            Center(
              child: Text(
                "第一屏",
                style: Theme.of(context).textTheme.labelLarge,
              ),
            ),
            Center(
              child: Text(
                "第二屏",
                style: Theme.of(context).textTheme.labelLarge,
              ),
            ),
            Center(
              child: Text(
                "第三屏",
                style: Theme.of(context).textTheme.labelLarge,
              ),
            ),
            Center(
              child: Text(
                "第四屏",
                style: Theme.of(context).textTheme.labelLarge,
              ),
            ),
          ]),
    );
  }
}

7.2 PageView.builder组件

import 'package:flutter/material.dart';

class PageViewBuilderPage extends StatefulWidget {
  const PageViewBuilderPage({super.key});

  @override
  State<PageViewBuilderPage> createState() => _PageViewBuilderPageState();
}

class _PageViewBuilderPageState extends State<PageViewBuilderPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("pageViewbuilder"),
        ),
        body: PageView.builder(
            itemCount: 5, //循环的次数
            itemBuilder: (context, index) {
              return Center(
                child: Text(
                  "第${index + 1}屏",
                  style: Theme.of(context).textTheme.labelLarge,
                ),
              );
            }));
  }
}

7.3 轮播组件swiper的封装

import 'package:flutter/material.dart';
import '../../widget/swiper.dart';

class PageViewSwiperPage extends StatefulWidget {
  const PageViewSwiperPage({super.key});

  @override
  State<PageViewSwiperPage> createState() => _PageViewSwiperPageState();
}

class _PageViewSwiperPageState extends State<PageViewSwiperPage> {
  List<String> list = [];

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    list = const [
      "https://img1.baidu.com/it/u=413643897,2296924942&fm=253&fmt=auto&app=138&f=JPEG?w=800&h=500",
      "https://img1.baidu.com/it/u=1919509102,1927615551&fm=253&fmt=auto&app=138&f=JPEG?w=889&h=500",
      "https://img0.baidu.com/it/u=3007048469,3759326707&fm=253&fmt=auto&app=138&f=JPEG?w=889&h=500"
    ];
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text("pageViewSwiper"),
        ),
        body: Swiper(list: list));
  }
}
import 'dart:async';

import 'package:flutter/material.dart';
// import '../widget/image.dart';

class Swiper extends StatefulWidget {
  final double width;
  final double height;
  final List<String> list;
  const Swiper(
      {super.key,
      this.height = 200,
      this.width = double.infinity,
      required this.list});

  @override
  State<Swiper> createState() => _SwiperState();
}

class _SwiperState extends State<Swiper> {
  int _currentIndex = 0;
  List<Widget> pagelist = [];
  late PageController _pageController;
  late Timer timer;
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    for (var i = 0; i < widget.list.length; i++) {
      pagelist.add(ImagePage(
          width: widget.width, height: widget.height, src: widget.list[i]));
    }
    _pageController = PageController(initialPage: 0);
    //定时器实现自动轮播
    timer = Timer.periodic(Duration(seconds: 3), (t) {
      _pageController.animateToPage(
          (_currentIndex + 1) % pagelist.length, //下一个页面
          duration: const Duration(microseconds: 200),
          curve: Curves.linear);
    });
  }

  @override
  void dispose() {
    //页面销毁时清除定时器
    // TODO: implement dispose
    super.dispose();
    timer.cancel(); //清除定时器
    _pageController.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        SizedBox(
            height: 200,
            child: PageView.builder(
                controller: _pageController, //控制页面
                onPageChanged: (index) {
                  setState(() {
                    _currentIndex = index % pagelist.length;
                  });
                },
                itemCount: 1000,
                itemBuilder: (context, index) {
                  return pagelist[index % pagelist.length]; //实现循环轮播的效果
                })),
        Positioned(
            right: 0,
            left: 0,
            bottom: 2,
            child: Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: List.generate(3, (index) {
                return Container(
                  height: 10,
                  width: 10,
                  margin: EdgeInsets.all(5),
                  decoration: BoxDecoration(
                      color: _currentIndex == index ? Colors.blue : Colors.grey,
                      borderRadius: BorderRadius.circular(5)),
                );
              }).toList(),
            ))
      ],
    );
  }
}

class ImagePage extends StatelessWidget {
  final double height;
  final double width;
  final String src;

  const ImagePage(
      {super.key,
      this.width = double.infinity,
      this.height = 200,
      required this.src});

  @override
  Widget build(BuildContext context) {
    return Container(
      width: width,
      height: height,
      child: Image.network(
        src,
        fit: BoxFit.cover,
      ),
    );
  }
}

 8.flutter中key以及通过全局key获取子widget实例

 8.1 flutter中key的作用

import 'package:flutter/material.dart';

//flutter中key是不能重复使用的，作为唯一标识，组件更新时其状态的保存主要是通过判断组件的类型
//或者key是否一致，如果类型不同时，类型已经足够区分不同组件，此时没必要使用key，但存在多个同意
//组件就需要key来判定，组件不同但是全局key一样也可保留组件的状态
class KeyPage extends StatefulWidget {
  const KeyPage({super.key});

  @override
  State<KeyPage> createState() => _KeyPageState();
}

//1.全局keyGlobalKey
//2.常用局部key有ValueKey、UniqueKey
class _KeyPageState extends State<KeyPage> {
  GlobalKey _globalKey1 = GlobalKey(); //定义全局key
  List<Widget> list = [];

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    list = [
      const Box(
        key: ValueKey("1"), //指定key
        color: Colors.red,
      ),
      Box(
        key: UniqueKey(), //生成唯一值
        color: Colors.yellow,
      ),
      Box(
        key: _globalKey1,
        color: Colors.blue,
      ),
    ];
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          setState(() {
            list.shuffle(); //对数据元素进行重新排序
          });
        },
        child: const Icon(Icons.refresh),
      ),
      appBar: AppBar(
        title: Text("flutter"),
      ),
      body: Center(
        child:
            Column(mainAxisAlignment: MainAxisAlignment.center, children: list),
      ),
    );
  }
}

class Box extends StatefulWidget {
  final Color color;
  const Box({super.key, required this.color});

  @override
  State<Box> createState() => _BoxState();
}

//定义盒子组件
class _BoxState extends State<Box> {
  late int _count = 0;
  @override
  Widget build(BuildContext context) {
    return Container(
      height: 100,
      width: 100,
      child: ElevatedButton(
          style: ButtonStyle(
              backgroundColor: MaterialStateProperty.all(widget.color)),
          onPressed: () {
            setState(() {
              _count++;
            });
          },
          child: Text("$_count")),
    );
  }
}

8.2 flutter 通过全局key获取子widget的属性和方法

import 'package:flutter/material.dart';

class Key2Page extends StatefulWidget {
  const Key2Page({super.key});

  @override
  State<Key2Page> createState() => _KeyPageState();
}

class _KeyPageState extends State<Key2Page> {
  GlobalKey _globalKey1 = GlobalKey(); //定义全局key

  @override
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          // 1.通过全局key获取 currentState子组件属性
          var boxState = _globalKey1.currentState as _BoxState;

          setState(() {
            boxState._count++;
          });
          //调用currentState子组件的方法
          boxState.run();
          //2.获取子widget
          var boxWidget = _globalKey1.currentWidget as Box;
          //3.获取子组件渲染属性
          var renderBox =
              _globalKey1.currentContext!.findRenderObject() as RenderBox;

          print(renderBox.size);
        },
        child: const Icon(Icons.add),
      ),
      appBar: AppBar(
        title: Text("flutter"),
      ),
      body: Center(
        child: Box(key: _globalKey1, color: Colors.blue),
      ),
    );
  }
}

//子widget
class Box extends StatefulWidget {
  final Color color;
  const Box({super.key, required this.color});

  @override
  State<Box> createState() => _BoxState();
}

//定义盒子组件
class _BoxState extends State<Box> {
  late int _count = 0;
  void run() {
    print("我是子组件的方法");
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      height: 100,
      width: 100,
      child: ElevatedButton(
          style: ButtonStyle(
              backgroundColor: MaterialStateProperty.all(widget.color)),
          onPressed: () {
            setState(() {
              _count++;
            });
          },
          child: Text("$_count")),
    );
  }
}

 9.动态列表

import 'dart:async';

import 'package:flutter/material.dart';

class AnimateListPage extends StatefulWidget {
  const AnimateListPage({super.key});

  @override
  State<AnimateListPage> createState() => _AnimateListPageState();
}

class _AnimateListPageState extends State<AnimateListPage> {
  final _globalKey = GlobalKey<AnimatedListState>(); //加上泛型AnimatedListState
  List<String> list = ["第一条", "第二条"];
  bool flag = true;
  Widget _BuildItem(index) {
    return ListTile(
      title: Text(list[index]),
      trailing: IconButton(
        icon: const Icon(Icons.delete),
        onPressed: () {
          _delete(index);
        },
      ),
    );
  }

  //删除
  _delete(index) {
    if (flag) {
      flag = false;
      _globalKey.currentState?.removeItem(index, (context, animation) {
        var removeItem = _BuildItem(index); //获取执行动画的元素
        list.removeAt(index); //数组中删除数据
        return FadeTransition(
          opacity: animation,
          child: removeItem,
        );
      });

      //解决快速删除时的bug
      Timer.periodic(Duration(milliseconds: 500), (timer) {
        flag = true;
        timer.cancel();
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          // setState(() {
          //   //使用setState给AnimatedList数据页面不更新
          //   list.add("新增的数据");
          // });
          //要通过insertItem来添加数据
          list.add("新增的数据");
          _globalKey.currentState?.insertItem(list.length - 1);
        },
        child: Icon(Icons.add),
      ),
      appBar: AppBar(
        title: Text("动态列表页面"),
      ),
      body: AnimatedList(
          key: _globalKey,
          initialItemCount: list.length,
          itemBuilder: (context, index, Animation) {
            //Animation动态的时间0-1，执行动画的元素child
            return FadeTransition(opacity: Animation, child: _BuildItem(index));
          }),
    );
  }
}

10.getx

10.1 getx的介绍

通俗的讲： 当我们想在多个页面（组件/Widget）之间共享状态（数据），或者一个页面（组件/Widget）中的多个子组件之间共享状态（数据），这个时候我们就可以用Flutter中的状态管理来管理统一的状态（数据），实现不同组件之间的传值和数据共享。现在Flutter的状态管理方案很多，redux、bloc、state、provider、Getx。provider是官方提供的状态管理解决方案，主要功能就是状态管理。Getx是第三方的状态管理插件，不仅具有状态管理的功能，还具有路由管理、主题管理、国际化多语言管理、Obx局部更新、网络请求、数据验证等功能，相比其他状态管理插件Getx 简单、功能强大并且高性能。
官网：https://pub.dev/packages/get
中文文档：https://github.com/jonataslaw/getx/blob/master/README.zh-cn.md

 10.2 安装使用

dependencies: get: ^4.6.5

10.3 getx中的dialog以及主题切换

import 'package:flutter/material.dart';

import 'package:get/get.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    //使用GetMaterialApp
    return GetMaterialApp(
      debugShowCheckedModeBanner: false, //去掉debug
      title: "getx app",
      theme: ThemeData(primarySwatch: Colors.blue),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("getx"),
      ),
      body: Center(
        child: Column(children: [
          ElevatedButton(
              onPressed: () {
                //getx默认弹框
                Get.defaultDialog(
                    title: "提示信息",
                    middleText: "你确定要删除么",
                    confirm: ElevatedButton(
                        onPressed: () {
                          print("确认");
                          Get.back(); //关闭弹框
                        },
                        child: const Text("确认")),
                    cancel:
                        ElevatedButton(onPressed: () {}, child: Text("取消")));
              },
              child: const Text("getx defaultDialog")),
          ElevatedButton(
              onPressed: () {
                //getx默认弹框
                Get.snackbar("提示", "你还没有登录",
                    snackPosition: SnackPosition.TOP); //修改位置
              },
              child: const Text("getx saackbar")),
          ElevatedButton(
              onPressed: () {
                //getx默认弹框
                Get.bottomSheet(Container(
                  height: 200,
                  child: Column(children: [
                    ListTile(
                      onTap: () {
                        //切换主题
                        Get.changeTheme(ThemeData.light());
                        Get.back();
                      },
                      leading: const Icon(
                        Icons.wb_sunny_outlined,
                      ),
                      title: const Text(
                        "白天模式",
                        style: TextStyle(color: Colors.blue),
                      ),
                    ),
                    ListTile(
                      onTap: () {
                        Get.changeTheme(ThemeData.dark());
                        Get.back();
                      },
                      leading: Icon(Icons.wb_sunny),
                      title: const Text("夜晚模式",
                          style: TextStyle(color: Colors.yellow)),
                    ),
                  ]),
                )); //修改位置
              },
              child: const Text("getx bottomSheet")),
        ]),
      ),
    );
  }
}

10.4 getx中的基础路由

import 'package:flutter/material.dart';

import 'package:get/get.dart';

//getx基础路由
void main() {
  runApp(GetMaterialApp(
    home: Home(),
  ));
}

class Home extends StatelessWidget {
  const Home({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("getx router"),
      ),
      body: Column(children: [
        ElevatedButton(
            onPressed: () {
              //1.基础路由跳转，可以定义跳转动画
              Get.to(Other(),
                  transition: Transition.fadeIn,
                  duration: Duration(milliseconds: 2000),
                  arguments: {"name": "张三", "age": 18}); //传参
              //2.跳转后不能回退
              // Get.off(Other());
              //3.跳转关闭之前所有路由
              // Get.offAll(Other());
            },
            child: Text("路由跳转"))
      ]),
    );
  }
}

class Other extends StatelessWidget {
  const Other({super.key});

  @override
  Widget build(BuildContext context) {
    //获取路由传过来的参数
    final res = Get.arguments;
    return Scaffold(
      appBar: AppBar(title: Text("other页面")),
      body: Center(
        child: Text("other页面" + '--' + res["name"]),
      ),
    );
  }
}

10.5 getx中的命名路由

import 'package:flutter/material.dart';
import 'package:flutter02/pages/user/login.dart';
import 'package:flutter02/routers/route.dart';

import 'package:get/get.dart';

//getx命名路由
void main() {
  runApp(GetMaterialApp(
    initialRoute: "/login", //初始化路由
    defaultTransition: Transition.zoom, //全局设置动画  
//配置路由
    getPages: [
      GetPage(name: "/", page: () => Home()),
      GetPage(name: "/other", page: () => Other()),
      GetPage(name: "/login", page: () => Login())
    ],
    //路由拦截
    routingCallback: (routing) => {print(routing?.current)},
  ));
}

class Home extends StatelessWidget {
  const Home({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("getx router"),
      ),
      body: Column(children: [
        ElevatedButton(
            onPressed: () {
              //1.命名路由跳转，
              Get.toNamed("/other", arguments: {"name": "张三", "age": 18}); //传参
              //2.跳转后不能回退
              //  Get.offNamed("/other", arguments: {"name": "张三", "age": 18});
              //3.跳转关闭之前所有路由
              // Get.offAllNamed("/other", arguments: {"name": "张三", "age": 18});
            },
            child: Text("路由跳转"))
      ]),
    );
  }
}

//其他页面
class Other extends StatelessWidget {
  const Other({super.key});

  @override
  Widget build(BuildContext context) {
    //获取路由传过来的参数
    final res = Get.arguments;
    return Scaffold(
      appBar: AppBar(title: Text("other页面")),
      body: Center(
        child: Text("other页面" + '--' + res["name"]),
      ),
    );
  }
}

//登录页面
class Login extends StatelessWidget {
  const Login({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("login"),
      ),
      body: Center(
          child: ElevatedButton(
        onPressed: () {
          Get.offNamed("/");
        },
        child: Text("跳转home"),
      )),
    );
  }
}

 10.6 getx状态管理

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

void main() {
  runApp(const GetMaterialApp(
    home: Home(),
  ));
}

class Home extends StatelessWidget {
  const Home({super.key});

  @override
  Widget build(BuildContext context) {
    //使用控制器根据依赖注入
    final controller = Get.put(Controller());
    //实例化类时转换为响应式变量
    final user = User1(name: "Camila", age: 18).obs;
    var num = 0;
    // final user = User();

    return Scaffold(
        appBar: AppBar(
          title: Text("state"),
        ),
        body: Center(
          child: Column(children: [
            //使用Obx包裹数据变为响应式数据
            Obx(() => Text('count1--' + '${controller.count1.value}')),
            GetX<Controller>(
              //需要加上value获取值
              builder: (controller) {
                print("count 1 rebuild");
                return Text('count1--' + '${controller.count1.value}');
              },
            ),
            GetX<Controller>(
              builder: (controller) {
                print("count 2 rebuild");
                return Text('count2--' + '${controller.count2.value}');
              },
            ),
            GetX<Controller>(
              builder: (controller) {
                print("count 3 rebuild");
                return Text('sum--' + '${controller.sum}');
              },
            ),
            ElevatedButton(
                onPressed: () {
                  //只会局部更新
                  controller.count1.value++;
                },
                child: Text("改变count1")),
            Obx(() => Text("age is ${user.value.age}")),
            ElevatedButton(
                onPressed: () {
                  //只会局部更新
                  user.update((user) {
                    // 这个参数是你要更新的类本身。
                    user?.name = 'Jonny';
                    user?.age = 20;
                  });
                },
                child: Text("改变User1")),
            //数据不需要加value获取值
            Obx(() => Text("list is ${controller.list}")),
            ElevatedButton(
                onPressed: () {
                  num++;
                  controller.list.add(num);
                },
                child: Text("改变list")),
          ]),
        ));
  }
}

//创建控制器
class Controller extends GetxController {
  //定义响应式变量
  final count1 = 1.obs;
  final count2 = 2.obs;
  int get sum => count1.value + count2.value;
  final list = [].obs;
  //初始化方法
  @override
  void onInit() {
    // TODO: implement onInit
    super.onInit();
    list.add(1);

    ///每次`count1`变化时调用。
    ever(count1, (_) => print("$_ has been changed"));

    ///只有在变量$_第一次被改变时才会被调用。
    once(count1, (_) => print("$_ was changed once"));

    ///防DDos - 每当用户停止输入1秒时调用，例如。
    debounce(count1, (_) => print("debouce$_"), time: Duration(seconds: 1));

    ///忽略1秒内的所有变化。节流
    interval(count1, (_) => print("interval $_"), time: Duration(seconds: 1));
  }
}

//类中定义响应式变量
class User {
  final name = "tom".obs;
  final age = 18.obs;
}
//也可先定义实例化时转换为obs
class User1 {
  User1({required String name, int? age});
  var name = "tom";
  var age = 18;
}

 

 

 

 

 

 

标签：const,Text,基础,dart,context,child,import,flutter
From： https://www.cnblogs.com/chenxian123m/p/fliutter_02.html

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