组件管理自己状态
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
//组件状态管理(自己管理自己的状态)
class MyApp extends StatelessWidget{
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter layout',
home: Scaffold(
appBar: AppBar(
title: Text('状态管理'),
),
body: Center(
child: TapboxA(),
)
),
);
}
}
//组件自己管理自己状态
class TapboxA extends StatefulWidget{
TapboxA({Key key}) :super(key:key);
@override
_TapboxAState createState()=>_TapboxAState();
}
//子类中更改状态
class _TapboxAState extends State<TapboxA>{
bool _active = false;
void _handleTap(){
setState(() {
_active = !_active;
});
}
@override
Widget build(BuildContext context) {
// TODO: implement build
return GestureDetector(
onTap: _handleTap,
child: Container(
child: Center(
child: Text(
_active?'Active':'Inactive',
style: TextStyle(
fontSize: 32.0,
color: Colors.white
),
),
),
width: 200.0,
height: 200.0,
decoration: BoxDecoration(
color: _active?Colors.lightGreen[700]:Colors.grey[600],
),
),
);
}
}
父组件管理子组件
import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart';
void main() => runApp(MyApp());
//组件状态管理(父 widget 管理 widget 的 state)
class MyApp extends StatelessWidget{
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter layout',
home: Scaffold(
appBar: AppBar(
title: Text('状态管理'),
),
body: Center(
child: ParentWidget(),
)
),
);
}
}
//管理状态的父组件
class ParentWidget extends StatefulWidget{
@override
_ParentWidgetState createState() => _ParentWidgetState();
}
class _ParentWidgetState extends State<ParentWidget>{
bool _active = false;
void _handleTapboxChanged(bool newValue){
setState(() {
_active = !_active;
});
}
@override
Widget build(BuildContext context) {
// TODO: implement build
return Container(
//onChanged回调方法调用的时候执行setstate方法
child: TapboxB(active:_active,onChanged: _handleTapboxChanged),
);
}
}
//子组件,状态由父组件管理,继承StatelessWidget
class TapboxB extends StatelessWidget{
final bool active;
final ValueChanged<bool> onChanged;//标记基本值更改的回调方法
TapboxB({Key key,this.active:false,@required this.onChanged}):super(key:key);
void _handleTap(){
//把状态改变的值通过回调方法传给父类去处理setstate方法
onChanged(!active);
}
@override
Widget build(BuildContext context) {
return GestureDetector(
onTap: _handleTap,
child: Container(
child: Center(
child: Text(
active?'active':'inactive',
style: TextStyle(fontSize: 32.0,color: Colors.white),
),
),
width: 200.0,
height: 200.0,
decoration: BoxDecoration(
color: active?Colors.lightGreen[700]:Colors.grey[600],
),
),
);
}
}
父组件管理子组件部分状态
import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart';
void main() => runApp(MyApp());
//组件状态管理(父 widget 管理 widget 的 state)
class MyApp extends StatelessWidget{
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter layout',
home: Scaffold(
appBar: AppBar(
title: Text('状态管理'),
),
body: Center(
child: ParentWidget(),
)
),
);
}
}
//父组件管理子组件部分状态
class ParentWidget extends StatefulWidget{
@override
_ParentWidgetState createState()=>_ParentWidgetState();
}
class _ParentWidgetState extends State<ParentWidget>{
bool _active = false;
void _handleTapboxChanged(bool newValue){
setState(() {
_active = !_active;
});
}
@override
Widget build(BuildContext context) {
// TODO: implement build
return Container(
child: TapboxC(active:_active,onChanged: _handleTapboxChanged),
);
}
}
// 子组件也管理部分自身状态 继承StatefulWidget
class TapboxC extends StatefulWidget{
final bool active;
final ValueChanged<bool> onChanged;
TapboxC({Key key,this.active:false,@required this.onChanged}):super(key:key);
@override
_TapboxCState createState()=> _TapboxCState();
}
class _TapboxCState extends State<TapboxC>{
bool _highlight = false;
//自己处理状态改变
void _handleTapDown(TapDownDetails details){
setState(() {
_highlight = true;
});
}
//自己处理状态改变
void _handleTapUp(TapUpDetails details){
setState(() {
_highlight = false;
});
}
//自己处理状态改变
void _handleTapCancel(){
setState(() {
_highlight = false;
});
}
//将自己的状态回调给父类进行处理
void _handleTap(){
widget.onChanged(!widget.active);
}
@override
Widget build(BuildContext context) {
// TODO: implement build
return GestureDetector(
onTapDown: _handleTapDown,
onTapUp: _handleTapUp,
onTap: _handleTap,
onTapCancel: _handleTapCancel,
child: Container(
child: Center(
child: Text(
widget.active ?'active':'inactive',
style: TextStyle(fontSize: 32.0,color: Colors.white),
),
),
width: 200.0,
height: 200.0,
decoration: BoxDecoration(
color: widget.active?Colors.lightGreen[700]:Colors.grey[600],
border:_highlight?Border.all(color: Colors.teal[700],width: 10.0):null,
),
),
);
}
}
更多地址: https://github.com/BlissYang91/my_flutter 欢迎star