概述
在flutter开发时,有时候点击某个按钮,只需要刷新指定控件,而不需要将整个页面都刷新.
思路: 在待刷新控件里定义一个点击方法,点击方法里刷新本控件. 点击指定按钮时,去调用此待刷新控件里的点击方法.
流程图
代码
main.dart
import 'package:flutter/material.dart';
import 'new_text.dart';
import 'new_button.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State {
GlobalKey textKey = GlobalKey(); //设置key,绑定待刷新控件.
var _count = 1;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
TextWidget(textKey), //传入key给待刷新控件
//自定义的ButtonWidget控件,会传入一个onPressed参数.这个参数是名为OnPressed的方法,方法无参数.
//该方法最终是传递给了new_button.dart的RaisedButton控件调用.
ButtonWidget(
onPressed: () {
_count++;
textKey.currentState.onPressed( _count); ///点击button，调用TextWidget的onPressed方法
},
),
],
),
),
);
}
} new_text.dart
import 'package:flutter/material.dart';
class TextWidget extends StatefulWidget {
//! 接收传过来的key
TextWidget(Key key) : super(key: key);
@override
State createState() {
return TextWidgetState();
}
}
class TextWidgetState extends State {
String _text="0";
@override
Widget build(BuildContext context) {
return Center(
child: Text(_text,style: TextStyle(fontSize: 20,color:Colors.green), ),
);
}
//在TextWidget的onPressed中单独调用TextWidget的setState,刷新本控件.
void onPressed(int count) {
setState(() {
_text = count.toString();
});
}
} new_button.dart
import 'new_text.dart';
import 'package:flutter/material.dart';
typedef onPressed_changestate();
class ButtonWidget extends StatefulWidget {
//类变量,作为调用类时的参数
onPressed_changestate onPressed;
ButtonWidget({this.onPressed});
@override
State createState() {
return _ButtonWidgetState(onPressed);
}
}
class _ButtonWidgetState extends State {
onPressed_changestate new_onPressed;
_ButtonWidgetState(this.new_onPressed);
@override
Widget build(BuildContext context) {
return Center(
child: RaisedButton(
child: Text('count++',style: TextStyle(fontSize: 20),),
onPressed: new_onPressed,
//new_onPressed是main.dart调用该控件时传递过来的方法
//也就是 onPressed: () {
// _count++;
// textKey.currentState.onPressed( _count);
// },
),
);
}
}