Flutter 代码分享（一）

main.dart

import 'package:flutter/material.dart';
import './home/home_view.dart';
import './messaage/message.dart';
import './me/me.dart';
import './set/settings.dart';

void main() => runApp(MyApp());

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: HomePage(),
      color: Colors.red,
      theme: ThemeData(
        backgroundColor: Colors.red,
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  HomePage({Key key}) : super(key: key);
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  int _currentIndex = 0;
  List <Widget> _pages;
  PageController _pageController;

  List tabbar = <BottomNavigationBarItem>[
    BottomNavigationBarItem(
      title: Text("首页"),
      icon: Icon(Icons.home),
    ),
    BottomNavigationBarItem(
      title: Text("消息"),
      icon: Icon(Icons.message),
    ),
    BottomNavigationBarItem(
      title: Text("我的"),
      icon: Icon(Icons.people),
    ),
    BottomNavigationBarItem(
      title: Text("设置"),
      icon: Icon(Icons.settings),
    ),
  ];

  @override
  void initState() {
    super.initState();
    _pageController = PageController(initialPage: _currentIndex);
    _pages = [
      HomeViewController(),
      MessageViewController(),
      MeViewController(),
      SettingsViewController(),
    ];
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: PageView.builder(
        itemBuilder: (BuildContext context, int index) {
          return _pages[index];
        },
        itemCount: _pages.length,
        controller: _pageController,
        onPageChanged: (int index) {
          setState(() {
            _currentIndex = index;
          });
        },
      ),
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: this._currentIndex,
        selectedFontSize: 12.0,
        type: BottomNavigationBarType.fixed,
        items: tabbar,
        onTap: (int index) {
          debugPrint("index = $index");
          setState(() {
            this._currentIndex = index;
            this._pageController.animateToPage(index,
                duration: Duration(microseconds: 200), curve: Curves.easeInOut);
          });
        },
      ),
    );
  }
}

home_view.dart

import 'package:flutter/material.dart';

class HomeViewController extends StatefulWidget {
  HomeViewController({Key key}) : super(key: key);

  _HomeViewControllerState createState() => _HomeViewControllerState();
}

class _HomeViewControllerState extends State<HomeViewController> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("首页"),
      ),
      body: Center(
        child: Container(
          height: 400.0,
          width: 300.0,
          color: Colors.red,
          child: MyStack(),
        ),
      ),
    );
  }
}

class MyStack extends StatelessWidget {
  const MyStack({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Stack(
      alignment: Alignment.center,
      children: <Widget>[

        Positioned(
          top: 20.0,
          left: 20.0,
          right: 20.0,
          child: Container(
            color: Colors.green[400],
            // alignment: Alignment(-0.7,-.7),
            alignment: Alignment.center,
            height: 240,
            child: Text(
              "朋友",
              style: TextStyle(fontSize: 40,color: Colors.yellow),
            ),
          ),
        ),

        Align(
          alignment: Alignment(-0.8, 0.8),
          child: Icon(
            Icons.skip_previous,
            color: Colors.white,
            size: 35.0,
          ),
        ),
        Align(
          alignment: Alignment(0, 0.8),
          child: Icon(
            Icons.play_arrow,
            color: Colors.white,
            size: 35.0,
          ),
        ),
        Align(
          alignment: Alignment(0.8, 0.8),
          child: Icon(
            Icons.skip_next,
            color: Colors.white,
            size: 35.0,
          ),
        ),
      ],
    );
  }
}

settings.dart

import 'package:flutter/material.dart';

class SettingsViewController extends StatefulWidget {
  SettingsViewController({Key key}) : super(key: key);

  _SettingsViewControllerState createState() => _SettingsViewControllerState();
}

class _SettingsViewControllerState extends State<SettingsViewController> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("设置"),
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.settings_overscan),
            tooltip: 'Navigration',
            onPressed: () {
              // debugPrint('search button is pressed.');
              showAlertDialog(context);
            },
          ),
        ],
      ),
      body: Container(
        alignment: Alignment.center,
        margin: EdgeInsets.all(10),
        color: Colors.blue,
        child: Column(
          children: <Widget>[
            Icon(Icons.add),
            Text("添加"),
          ],
        ),
      ),
    );
  }
}

void showAlertDialog(BuildContext context) {
  showDialog(
      context: context,
      builder: (_) => new AlertDialog(
              title: new Text("Dialog Title"),
              content: new Text("This is my content"),
              actions: <Widget>[
                new FlatButton(
                  child: new Text("CANCEL"),
                  onPressed: () {
                    Navigator.of(context).pop();
                  },
                ),
                new FlatButton(
                  child: new Text("OK"),
                  onPressed: () {
                    Navigator.of(context).pop();
                  },
                )
              ]));
}