[Detailed] Flutter's Global State Management Provider

[Detailed] Flutter's Global State Management Provider

@author
As.Kai

First import dependencies

provide: ^1.0.2

The latest version can be viewed on the pub

After importing, create a state management Provide under the lib folder:

Official website example:
Create a static page data management++ Demo

eg:
Create a counter.dart file in the provide folder:

import 'package:flutter/cupertino.dart';

class Counter with ChangeNotifier{
	int value = 0;
	increment(){
		value++;
//内部方法 用户每次调用value++方法 会通知我们执行了该方法
//局部刷新Widget
		notifyListeners();
	}
}

Note that the notifyListeners(); method means monitoring and partial refreshing. After
writing the ++ method, you must write the dependency in main.dart:

void main(){
//连接状态管理器
	var counter = new Counter();
	var providers = new Providers();
//依赖 (规范) 如果有多个管理器 分号在最后一个管理器结束
//改泛型和管理器名称
	providers..provide(
		Provider<Counter>.value(counter)
		);
	//多管理器配置（多管理器除最后一个分号结束，其他不需要分号）
// ..provide(Provider<Counter>.value(counter));
// ..provide(Provider<Counter>.value(counter));
	runApp(
		ProviderNode(
			child: MyApp(),providers: providers,
			)
		);
}

Pay attention to the configuration of runApp(), many people will forget this step of configuration and cause the program to report an error
Write a text and a button on the layout page, click the button text number plus 1
reference method: the
text needs to be wrapped with the Provide control <generic manager name> {

There is a constructor build(

3 parameters (context, subclass child, controller counter)) { Directly return a control eg: return new Text('${counter.value}'); OK } }

Code:

class Number extends StatelessWidget {
@override
Widget build(BuildContext context) {
	return Container(
	//需要包裹一层Provide<Counter>泛型
		child: new Provide<Counter>(
	//构造器
			builder: (context,child,counter){
			return new Text('${counter.value}');
				},
			),
		);
	}
}

At the button:
Click the event to call the ++ method in the manager.
Call the method:
Provide.value<generic manager class Counter>(context).increment();

Code:

class MyButton extends StatelessWidget {
@override
Widget build(BuildContext context) {
	return new RaisedButton(
	//点击事件
		onPressed: () {
	//通过Provide.value<>泛型的方式获取上下文后
	// 使用我们创建的increment value++方法
		Provide.value<Counter>(context).increment();
		},
			child: new Text('状态管理点击递增'),
		);
	}
}

A simple Provide is complete. Flutter run. Let's see the effect!

Follow me and grow together!
-As.Kai