更新了 provider example

Author: Vadaski

image/provider_example.gif

@@ -3,8 +3,12 @@
 ## 简介
 使用 Google 官方推荐的状态管理 [Provider](https://pub.dev/packages/provider#-installing-tab-) 的 demo。详细了解请看这里：[Flutter | 状态管理指南篇——Provider](https://juejin.im/editor/posts/5d00a84fe51d455a2f22023f)
 
+
+
+[更新]：Demo 新增单页面状态提供方式，供参考
+
 ## 样例
-![](https://user-gold-cdn.xitu.io/2019/6/12/16b4c691828e5a7a?w=333&h=676&f=gif&s=235209)
+![provider_example](../../../image/provider_example.gif)
 
 ## Getting Started
 

mecury_project/example/provider_example/README.md

@@ -0,0 +1,14 @@
+import 'package:flutter/material.dart';
+
+class ColorModel with ChangeNotifier {
+  int _seed = 0xFFFF9000;
+  Color _color = Color(0xFFFF9000);
+
+  get color => _color;
+
+  changeColor() {
+    _seed += 30;
+    _color = Color(_seed);
+    notifyListeners();
+  }
+}

mecury_project/example/provider_example/lib/color_model.dart

@@ -1,11 +1,14 @@
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 import 'counter_model.dart';
+import 'color_model.dart';
 
 class FirstScreen extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
-    final counter = Provider.of<CounterModel>(context,);
+    final counter = Provider.of<CounterModel>(
+      context,
+    );
     final textSize = Provider.of<int>(context);
 
     return Scaffold(
@@ -29,32 +32,116 @@ class FirstScreen extends StatelessWidget {
   }
 }
 
+/// This is a single page provider,
+/// it will be destroyed when the page is removed,
+/// and the status will be reset.
+
+class SecondScreenProvider extends StatefulWidget {
+  final Widget child;
+
+  SecondScreenProvider({@required this.child});
+
+  @override
+  _SecondScreenProviderState createState() => _SecondScreenProviderState();
+}
+
+class _SecondScreenProviderState extends State<SecondScreenProvider> {
+  ColorModel _colorModel = ColorModel();
+
+  @override
+  Widget build(BuildContext context) {
+    return ChangeNotifierProvider.value(
+      value: _colorModel,
+      child: widget.child,
+    );
+  }
+}
+
 class SecondScreen extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
-    return Scaffold(
-      appBar: AppBar(
-        title: Text('Second Page'),
+    return SecondScreenProvider(
+      child: DefaultTabController(
+        length: 3,
+        child: Scaffold(
+          appBar: buildAppBar(),
+          body: TabBarView(children: [
+            buildCounterText(),
+            showIconWithColor(),
+            showIconWithColor(),
+          ]),
+          floatingActionButton: buildActionButtons(),
+        ),
       ),
-      body: Consumer2<CounterModel, int>(
-        builder: (context, CounterModel counter, int textSize, child) {
-          return Center(
-            child: Text(
-              'Value: ${counter.value}',
-              style: TextStyle(
-                fontSize: textSize.toDouble(),
-              ),
+    );
+  }
+
+  Column buildActionButtons() {
+    return Column(
+      mainAxisAlignment: MainAxisAlignment.end,
+      children: <Widget>[
+        Consumer<ColorModel>(
+          builder: (context, ColorModel colorModel, child) {
+            return FloatingActionButton(
+              heroTag: 'no_hero',
+              child: Icon(Icons.swap_horizontal_circle),
+              onPressed: () {
+                colorModel.changeColor();
+              },
+            );
+          },
+        ),
+        SizedBox(height: 20),
+        Consumer<CounterModel>(
+          builder: (context, CounterModel counter, child) =>
+              FloatingActionButton(
+            onPressed: () => counter.increment(),
+            child: child,
+          ),
+          child: Icon(Icons.add),
+        ),
+      ],
+    );
+  }
+
+  Consumer2<CounterModel, int> buildCounterText() {
+    return Consumer2<CounterModel, int>(
+      builder: (context, CounterModel counter, int textSize, child) {
+        return Center(
+          child: Text(
+            'Value: ${counter.value}',
+            style: TextStyle(
+              fontSize: textSize.toDouble(),
             ),
+          ),
+        );
+      },
+    );
+  }
+
+  AppBar buildAppBar() {
+    return AppBar(
+      title: Text('Second Page'),
+      bottom: TabBar(tabs: [
+        Tab(text: 'show counter'),
+        Tab(text: 'show color'),
+        Tab(text: 'show color'),
+      ]),
+    );
+  }
+
+  Container showIconWithColor() {
+    return Container(
+      alignment: Alignment.center,
+      child: Consumer<ColorModel>(
+        builder: (context, ColorModel colorModel, child) {
+          return Icon(
+            Icons.stars,
+            color: colorModel.color,
+            size: 100,
           );
         },
       ),
-      floatingActionButton: Consumer<CounterModel>(
-        builder: (context, CounterModel counter, child) => FloatingActionButton(
-              onPressed: () => counter.increment(),
-              child: child,
-            ),
-        child: Icon(Icons.add),
-      ),
     );
   }
 }