今天学习下Flutter中state管理的第三方scoped_model.
其中,scoped_model: 1.0.1

代码结构如图所示:
scoped_model_demo_代码结构

下面是各文件的源码.

main.dart

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import 'package:flutter/material.dart';
import 'package:scoped_model_demo/model/main_model.dart';
import 'package:scoped_model/scoped_model.dart';
import 'top_screen.dart';

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

class MyApp extends StatelessWidget {
//创建顶层状态
MainModel countModel = MainModel();
// This widget is the root of your application.

@override
Widget build(BuildContext context) {
return ScopedModel<MainModel>(
model: countModel,
child: new MaterialApp(
title: 'Flutter Demo',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: TopScreen(),
),
);
}
}

tabbar.dart

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import 'package:flutter/material.dart';
import 'One/one.dart';
import 'Two/two.dart';

class Tabbar extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
debugShowCheckedModeBanner: false, home: new MainPageWidget());
}
}

class MainPageWidget extends StatefulWidget {
@override
State<StatefulWidget> createState() {
return new MainPageState();
}
}

class MainPageState extends State<MainPageWidget> {
int _tabIndex = 0;
var tabImages;
var appBarTitles = ['One', 'Two'];
/*
* 存放二个页面,跟fragmentList一样
*/
var _pageList;

/*
* 根据选择获得对应的normal或是press的icon
*/
Image getTabIcon(int curIndex) {
if (curIndex == _tabIndex) {
return tabImages[curIndex][1];
}
return tabImages[curIndex][0];
}
/*
* 获取bottomTab的颜色和文字
*/
Text getTabTitle(int curIndex) {
if (curIndex == _tabIndex) {
return new Text(appBarTitles[curIndex],
style: new TextStyle(fontSize: 14.0, color: const Color(0xff1296db)));
} else {
return new Text(appBarTitles[curIndex],
style: new TextStyle(fontSize: 14.0, color: const Color(0xff515151)));
}
}
/*
* 根据image路径获取图片
*/
Image getTabImage(path) {
return new Image.asset(path, width: 24.0, height: 24.0);
}


void initData() {
/*
* 初始化选中和未选中的icon
*/
tabImages = [
[getTabImage('images/tab/one.png'), getTabImage('images/tab/one_active.png')],
[getTabImage('images/tab/two.png'), getTabImage('images/tab/two_active.png')],
];
/*
* 子界面
*/
_pageList = [
new One(),
new Two(),
];
}

@override
Widget build(BuildContext context) {
//初始化数据
initData();
return Scaffold(
body: _pageList[_tabIndex],
bottomNavigationBar: new BottomNavigationBar(
items: <BottomNavigationBarItem>[
new BottomNavigationBarItem(
icon: getTabIcon(0), title: getTabTitle(0)),
new BottomNavigationBarItem(
icon: getTabIcon(1), title: getTabTitle(1)),
],
type: BottomNavigationBarType.fixed,
//默认选中首页
currentIndex: _tabIndex,
iconSize: 24.0,
//点击事件
onTap: (index) {
setState(() {
_tabIndex = index;
});
},
));
}
}

top_screen.dart

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import 'package:flutter/material.dart';
import 'package:scoped_model_demo/model/main_model.dart';
import 'package:scoped_model/scoped_model.dart';
import 'tabbar.dart';

class TopScreen extends StatefulWidget {
@override
_TopScreenState createState() => _TopScreenState();
}

class _TopScreenState extends State<TopScreen> {
//静态获取model用法实例
Model getModel(BuildContext context) {
//直接使用of
final countModel = ScopedModel.of<MainModel>(context);
//使用CountModel中重写的of
final countModel2 = MainModel().of(context);

countModel.increment();
countModel2.increment();
return countModel;
// return countMode2;
}


@override
Widget build(BuildContext context) {
return ScopedModelDescendant<MainModel>(
builder: (context,child,model){
return Tabbar();
},
);
}
}

main_model.dart

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import 'package:scoped_model/scoped_model.dart';

class MainModel extends Model{
int _count = 0;
get count => _count;

void increment(){
_count++;
notifyListeners();
}

MainModel of(context) =>
ScopedModel.of<MainModel>(context);
}

one.dart

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import 'package:flutter/material.dart';
import 'package:scoped_model_demo/model/main_model.dart';
import 'package:scoped_model/scoped_model.dart';

class One extends StatefulWidget {
@override
_OneState createState() => _OneState();
}

class _OneState extends State<One> {
//静态获取model用法实例
Model getModel(BuildContext context) {
//直接使用of
final countModel = ScopedModel.of<MainModel>(context);
//使用CountModel中重写的of
final countModel2 = MainModel().of(context);

countModel.increment();
countModel2.increment();
return countModel;
// return countMode2;
}

@override
Widget build(BuildContext context) {
return ScopedModelDescendant<MainModel>(
builder: (context, child, model) {
return Scaffold(
appBar: AppBar(
title: Text('One One'),
),
body: Center(
child: Column(
children: <Widget>[
Text(
model.count.toString(),
style: TextStyle(fontSize: 22.0),
),
RaisedButton(
child: Text('加1'),
onPressed: () => model.increment(),
),
],
),
),
);
},
);
}
}

two.dart

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import 'package:flutter/material.dart';
import 'package:scoped_model_demo/model/main_model.dart';
import 'package:scoped_model/scoped_model.dart';

class Two extends StatefulWidget {
@override
_TwoState createState() => _TwoState();
}

class _TwoState extends State<Two> {
//静态获取model用法实例
Model getModel(BuildContext context){
//直接使用of
final countModel = ScopedModel.of<MainModel>(context);
//使用CountModel中重写的of
final countModel2 = MainModel().of(context);

countModel.increment();
countModel2.increment();
return countModel;
// return countMode2;
}

@override
Widget build(BuildContext context) {
return ScopedModelDescendant<MainModel>(
builder: (context,child,model){
return Scaffold(
appBar: AppBar(
title: Text('Two Screen'),
),
body: Center(
child: Text(
model.count.toString(),
style: TextStyle(fontSize: 48.0),
),
)
);
},
);
}
}

效果图:
scoped_model_demo_result

源码

另外:其他管理库学习

另外:Flutter学习demo