flutter AppBar和SliverAppBar,以及Scaffold.appBar

AppBar

import 'package:flutter/material.dart';

void main() {
  runApp( MaterialApp(
    title: 'Flutter gesture',
    home: _home(),
  ));
}


class _home extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _homeState();
  }
}

class _homeState extends State<_home> {
  final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
  final SnackBar snackBar = const SnackBar(content: Text('Showing Snackbar'));

  void openPage(BuildContext context) {
    Navigator.push(context, MaterialPageRoute(
      builder: (BuildContext context) {
        return Scaffold(
          appBar: AppBar(
            title: const Text('Next page'),
          ),
          body: const Center(
            child: Text(
              'This is the next page',
              style: TextStyle(fontSize: 24),
            ),
          ),
        );
      },
    ));
  }

// ...

  Widget build(BuildContext context) {
    return Scaffold(
      key: scaffoldKey,
      appBar: AppBar(
        title: const Text('AppBar Demo'),
        actions: <Widget>[
          IconButton(
            icon: const Icon(Icons.add_alert),
            tooltip: 'Show Snackbar',
            onPressed: () {
              scaffoldKey.currentState.showSnackBar(snackBar);
            },
          ),
          IconButton(
            icon: const Icon(Icons.navigate_next),
            tooltip: 'Next page',
            onPressed: () {
              openPage(context);
            },
          ),
        ],
      ),
      body: const Center(
        child: Text(
          'This is the home page',
          style: TextStyle(fontSize: 24),
        ),
      ),
    );
  }
}

SliverAppBar：参照https://blog.csdn.net/u011272795/article/details/82740389

import 'package:flutter/material.dart';

void main() {
  runApp( MaterialApp(
    title: 'Flutter gesture',
    home: DiscoverListPage(),
  ));
}

class DiscoverListPage extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => DiscoverListState();
}

class DiscoverListState extends State<DiscoverListPage>
    with TickerProviderStateMixin {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: NestedScrollView(
          headerSliverBuilder: _sliverBuilder,
          body: Center(
            child: ListView.builder(
              itemBuilder: _itemBuilder,
              itemCount: 150,
            ),
          )),
    );
  }

  List<Widget> _sliverBuilder(BuildContext context, bool innerBoxIsScrolled) {
    return <Widget>[
      SliverAppBar(
        //标题居中
        centerTitle: true,
        //展开高度200
        expandedHeight: 150.0,
        //不随着滑动隐藏标题
        floating: false,
        //固定在顶部
        pinned: true,
        flexibleSpace: FlexibleSpaceBar(
          centerTitle: true,
          title: Text('我是一个FlexibleSpaceBar'),
          background: Image.network(
            "https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1531798262708&di=53d278a8427f482c5b836fa0e057f4ea&imgtype=0&src=http%3A%2F%2Fh.hiphotos.baidu.com%2Fimage%2Fpic%2Fitem%2F342ac65c103853434cc02dda9f13b07eca80883a.jpg",
            fit: BoxFit.cover,
          ),
        ),
      ),
      SliverPersistentHeader(
        //不随着滑动隐藏标题
          floating: false,
        pinned: true,//固定在顶部

          delegate: _SliverAppBarDelegate(

              TabBar(
            indicatorColor:Colors.blue[300],
            labelColor: Colors.red,
            unselectedLabelColor: Colors.grey,
            tabs: [
              Tab(icon: Icon(Icons.cake), text: '左侧'),
              Tab(icon: Icon(Icons.golf_course), text: '右侧'),

            ],
            controller: TabController(length: 2, vsync: this),
          )))
    ];
  }

  Widget _itemBuilder(BuildContext context, int index) {
    return ListTile(
      leading: Icon(Icons.android),
      title: Text('无与伦比的标题+$index'),
    );
  }
}

class _SliverAppBarDelegate extends SliverPersistentHeaderDelegate {
  _SliverAppBarDelegate(this._tabBar);

  final TabBar _tabBar;

  @override
  double get minExtent => _tabBar.preferredSize.height;

  @override
  double get maxExtent => _tabBar.preferredSize.height;

  @override
  Widget build(
      BuildContext context, double shrinkOffset, bool overlapsContent) {
    return Container(
      color: Colors.lightGreen[300],
      child: _tabBar,
    );
  }

  @override
  bool shouldRebuild(_SliverAppBarDelegate oldDelegate) {
    return false;
  }
}

Scaffold.appBar

import 'package:flutter/material.dart';

void main() {
  runApp( MaterialApp(
    title: 'Flutter gesture',
//    home: TutorialHome(),
    home: _home(),
  ));
}


class _home extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _homeState();
  }
}

class _homeState extends State<_home> {
  int _count = 0;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: new AppBar(
        backgroundColor: Colors.green,//设置标题栏的背景颜色
        title: new Title(
          child:new Text(
            '这是一个标题',
            style: new TextStyle(
              fontSize: 20.0,
              color: Colors.white,
            ),
          ),
          color: Colors.white,//设置标题栏文字的颜色(new title的时候color不能为null不然会报错一般可以不用new title 直接new text,不过最终的文字里面还是以里面new text的style样式文字颜色为准)
        ),
        centerTitle: true,//设置标题居中
        elevation: 10.0,//设置标题栏下面阴影的高度
        leading: new Builder(
            builder: (BuildContext context){
              return new GestureDetector(//设置事件
                child: new Icon(//设置左边的图标
                  Icons.account_circle,//设置图标内容
                  color: Colors.white,//设置图标的颜色
                ),
                onTap:(){
                  print('点击');
                },
                onLongPress: (){
                  Scaffold.of(context).showSnackBar(
                      new SnackBar(content: new Text('长按'))
                  );
                },
                onDoubleTap: (){
                  Scaffold.of(context).showSnackBar(
                      new SnackBar(content: new Text('双击'))
                  );
                },
              );
            }
        ),
//        brightness:Brightness.dark,//设置明暗模式（不过写了没看出变化，后面再看）
        primary: true,//是否设置内容避开状态栏
//        flexibleSpace: ,//伸缩控件后面再看
//        automaticallyImplyLeading: true,
        actions: <Widget>[ //设置显示在右边的控件
          new Padding(
            child: Row(
              children: <Widget>[
                Container(
                  margin: EdgeInsets.fromLTRB(0, 0, 25, 0),//调整间距
                  child: new Icon(//设置左边的图标
                    Icons.add,//设置图标内容
                    color: Colors.white,//设置图标的颜色
                  ),
                ),
                Container(
                  child: new Icon(//设置左边的图标
                    Icons.account_circle,//设置图标内容
                    color: Colors.white,//设置图标的颜色
                  ),
                ),
              ],
           ),

            padding: EdgeInsets.all(10.0),
          ),
        ],
        bottom:PreferredSize(//设置标题下面的view
          child: new Container(
            height: 50.0,
            child: new Center(
              child: new Text(
                '显示在title下面',
              ),
            ),
            decoration: BoxDecoration(
              color: Colors.red,
            ),
          ),
          preferredSize: Size.fromHeight(50.0),
        ),
      ),

    );
  }
}

跑起来