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Pluribus modis volitantem ad effectum deducendi partialis reficiendi

2024-07-12

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Tabula contentorum

Praefatio

1. momentum loci reficite

1. conceptus

2. momentum

2. Pluribus modis ad effectum deducendi partialis reficiendi

1. utere setState modum pro parte reficiendi

2. usus StatefulWidget et InheritedWidget ad partem reficiendi III

3.ValueNotifier和ValueListenableBuilder

4.StreamBuilder

5.Provider

6.GetX

7. Usus GlobalKey

Praefatio

In Flutter, administratione civitatis significat quomodo rem publicam datam in applicatione regere et renovare et secundum mutationes status UI renovare. Administratio status efficax potest auxilium tincidunt efficaces et conservabiles applicationes creare.

setState est modus administrationis fundamentalis status in Flutter. Scimus utique, cum modum statutum vocamus, pagina redrawn erit major effectus.

Quid ergo modi sunt in Flutter ut UI partim reficiat?

1. momentum loci reficite

1. conceptus

Refectio partialis significat solum partem interfaciendi, non totam paginam ad refrigerium. Hoc melius perficiendi et usus usoris.

2. momentum

  1. Vitare necesse redraws et amplio perficiendi
  2. Provide leviore usuario
  3. Redigendum resource consummatio

2. Pluribus modis ad effectum deducendi partialis reficiendi

1. utere setState modum pro parte reficiendi

setState publica administratio methodi in Flutter frequentissima est. Solet notificare compagem status mutationum, ducens ad refectionem interfaciendi.

Cum Voltianum consilium creamus, exemplum timeris ab systemate defalta generatum exemplum setState partialis reficiendi est.

  1. import 'package:flutter/material.dart';
  2.  
  3. class SetStateMainPage extends StatefulWidget {
  4.   final String title;
  5.   const SetStateMainPage({super.key, required this.title});
  6.  
  7.   @override
  8.   State<SetStateMainPage> createState() => _SetStateMainPageMainPageState();
  9. }
  10.  
  11. class _SetStateMainPageMainPageState extends State<SetStateMainPage> {
  12.   int _count = 0;
  13.  
  14.   @override
  15.   Widget build(BuildContext context) {
  16.     return Scaffold(
  17.       appBar: AppBar(
  18.         title: Text(widget.title),
  19.       ),
  20.       body: Center(
  21.         child: Text(
  22.           '您点击了$_count次',
  23.           style: const TextStyle(fontSize: 12, fontWeight: FontWeight.bold),
  24.         ),
  25.       ),
  26.       floatingActionButton: FloatingActionButton(
  27.           child: const Icon(Icons.add),
  28.           onPressed: () {
  29.             setState(() {
  30.               _count++;
  31.             });
  32.           },
  33.       )
  34.     );
  35.   }
  36. }

Figure 1.setState partialis reficite

Cum pagina relative simplex sit, recta ratione setState uti potes ad UI partim reficiendi.

Usus missionum: mutationes status simplices, ut globuli strepita computatio, status commutatio, etc.

Cautiones:

  1. Saepe vocat ad setState perficiendi causa potest proventus
  2. Vitare vocantem setState in modum constructum

2. usus StatefulWidget et InheritedWidget ad partem reficiendi III

        StatefulWidget componens cum re publica ;InheritedWidget Adsuesco assuesco data communicare in ligno componente.

Cum opus est ad notitias communicandas, considerare possumus StatefulWidget et InheritedWidget ut partem recreet UI.

Codicem integrum sic habet:

Figure 2. III refice communicando notitia

  1. import 'package:flutter/material.dart';
  2.  
  3. class MyInheritedWidget extends InheritedWidget {
  4.   final int counter;
  5.   const MyInheritedWidget({
  6.     super.key,
  7.     required this.counter,
  8.     required super.child,
  9.   });
  10.   @override
  11.   bool updateShouldNotify(covariant InheritedWidget oldWidget) {
  12.     return true;
  13.   }
  14.   static MyInheritedWidget? of(BuildContext context) {
  15.     return context.dependOnInheritedWidgetOfExactType<MyInheritedWidget>();
  16.   }
  17. }
  18.  
  19. class InheritedWidgetPage extends StatefulWidget {
  20.   final String title;
  21.   const InheritedWidgetPage({super.key, required this.title});
  22.  
  23.   @override
  24.   State<InheritedWidgetPage> createState() => _InheritedWidgetPageState();
  25. }
  26.  
  27. class _InheritedWidgetPageState extends State<InheritedWidgetPage> {
  28.   int counter = 0;
  29.   void _incrementCounter() {
  30.     setState(() {
  31.       counter++;
  32.     });
  33.   }
  34.  
  35.   @override
  36.   Widget build(BuildContext context) {
  37.     return MyInheritedWidget(
  38.       counter: counter,
  39.       child: Scaffold(
  40.         appBar: AppBar(
  41.           title: Text(widget.title),
  42.         ),
  43.         body: Center(child: Column(
  44.           children: [
  45.             const Divider(),
  46.             const CounterDisplay(),
  47.             const SizedBox(height: 20),
  48.             ElevatedButton(
  49.               onPressed: _incrementCounter,
  50.               child: const Text('add'),
  51.             ),
  52.           ],
  53.         ),),
  54.       ),
  55.     );
  56.   }
  57. }
  58.  
  59. class CounterDisplay extends StatelessWidget {
  60.   const CounterDisplay({super.key});
  61.   @override
  62.   Widget build(BuildContext context) {
  63.     final inheritedWidget = MyInheritedWidget.of(context);
  64.     return Text('点击次数: ${inheritedWidget?.counter}');
  65.   }
  66. }

Praecipuae usus missionum huius methodi sunt: ​​quando communicatio status in arbore componente, ut thema, occasus linguae, etc.

Utilitas est ut communicatio notitiae conveniat, et signum introductio

Incommodum est quod multiplex est ad usus et effectus afficiendos.

3.ValueNotifier和ValueListenableBuilder

        ValueNotifier Est simplex status administratio instrumentum;ValueListenableBuilder magnaValueNotifier Mutatio.

Usus est etiam valde simplex;

1. Instantiate ValueNotifier

2. The Widget object ut viverra involvitur cum ValueListenableBuilder

3. Quomodo mutatio eventu, Urguet notitia

Cum superioribus rationibus, haec ratio est simplex et facilis ad usum, et effectus est etiam altissimus.

Incommoda: tantum tractamus simplex status mutationes

Codicem integrum sic habet:

  1. import 'package:flutter/material.dart';
  2.  
  3. class ValueNotifierPage extends StatefulWidget {
  4.   final String title;
  5.   const ValueNotifierPage({super.key, required this.title});
  6.  
  7.   @override
  8.   State<ValueNotifierPage> createState() => _ValueNotifierPageState();
  9. }
  10.  
  11. class _ValueNotifierPageState extends State<ValueNotifierPage> {
  12.  
  13.   final ValueNotifier<int> _counter = ValueNotifier<int>(0);
  14.  
  15.   @override
  16.   Widget build(BuildContext context) {
  17.     return Scaffold(
  18.         appBar: AppBar(
  19.           title: Text(widget.title),
  20.         ),
  21.         body: Center(
  22.           child: ValueListenableBuilder<int>(
  23.             valueListenable: _counter,
  24.             builder: (context, value, child) {
  25.               return Text(
  26.                 '您点击了$value次',
  27.                 style: const TextStyle(fontSize: 12, fontWeight: FontWeight.bold),
  28.               );
  29.             },
  30.           )
  31.         ),
  32.         floatingActionButton: FloatingActionButton(
  33.           child: const Icon(Icons.add),
  34.           onPressed: () {
  35.             _counter.value ++;
  36.           },
  37.         )
  38.     );
  39.   }
  40. }

4.StreamBuilder

Amnis objectus est eventus asynchronos tradendi, et eventus per StreamController mitti potest. Ubi opus UI recreare debes, eventum ad Stream mittere potes, tum StreamBuilder utere ut Stream audias. Haec methodus aptus est ad condiciones in quibus multi asynchroni eventus viverra debent.

Cum opus est ut asynchronous notitiarum rivorum processus, ut petitiones retis, notitia real-time, etc., considerare possumus StreamBuilder usura. Exempli gratia, in hoc exemplo methodum asynchronam scripsimus quae petitionem retis simulat.

Utilitas huius methodi est ut petitiones asynchronas verius cohibere possit, sicut status retis petitiones, etc. Sed Dioor est complexior et plura requirere potest codicem.

Codicem integrum sic habet:

  1. import 'dart:async';
  2. import 'package:flutter/material.dart';
  3.  
  4. class StreamBuilderRefreshUIPage extends StatefulWidget {
  5.   final String title;
  6.   const StreamBuilderRefreshUIPage({super.key, required this.title});
  7.  
  8.   @override
  9.   State<StreamBuilderRefreshUIPage> createState() =>
  10.       _StreamBuilderRefreshUIPageState();
  11. }
  12.  
  13. class _StreamBuilderRefreshUIPageState extends State<StreamBuilderRefreshUIPage> {
  14.   late Future<String> _data;
  15.  
  16.   Future<String> fetchData() async {
  17.     // 模拟网络请求延迟
  18.     await Future.delayed(const Duration(seconds: 2));
  19.     // 返回模拟数据
  20.     return 'Hello, Flutter!';
  21.   }
  22.  
  23.   @override
  24.   void initState() {
  25.     // TODO: implement initState
  26.     super.initState();
  27.     _data = fetchData();
  28.   }
  29.  
  30.   @override
  31.   Widget build(BuildContext context) {
  32.     return Scaffold(
  33.       appBar: AppBar(
  34.         title: Text(widget.title),
  35.       ),
  36.       body: Center(
  37.         child: FutureBuilder<String>(
  38.           future: _data,
  39.           builder: (context, snapshot) {
  40.             if (snapshot.connectionState == ConnectionState.waiting) {
  41.               return const CircularProgressIndicator();
  42.             } else if (snapshot.hasError) {
  43.               return Text('Error: ${snapshot.error}');
  44.             } else {
  45.               return Text('Data: ${snapshot.data}');
  46.             }
  47.           },
  48.         ),
  49.       ),
  50.       floatingActionButton: FloatingActionButton(
  51.         onPressed: fetchData,
  52.         tooltip: 'Increment',
  53.         child: const Icon(Icons.add),
  54.       ),
  55.     );
  56.   }
  57. }

5.Provider

       Provider Res publica est procuratio solutionis a Flutter commendatae.Consumer Legebat et monitor status.

Timorem etiam in exemplum sumamus.

1. Primum Providentem importamus.

provisor: ^6.1.2

2. Customize in ChangeNotifier classis.

ChangeNotifier simplex genus est in SDK Flutter. Adhibetur notificationes auditoribus mittere. Aliis verbis, si in ChangeNotifier definitur, suae civitatis mutationes subscribere potes. (Similis est nota servatoris exemplaris).

In codice efficiendi cupimus, duae variabiles sunt _contra1 et _contra.

  1. class CounterModel extends ChangeNotifier {
  2.   int _counter1 = 0;
  3.   int _counter2 = 0;
  4.   void addCounter1(){
  5.     debugPrint('counter:$_counter1');
  6.     _counter1 += 1;
  7.     notifyListeners();
  8.   }
  9.   void addCounter2(){
  10.     debugPrint('counter:$_counter2');
  11.     _counter2 += 1;
  12.     notifyListeners();
  13.   }
  14. }

3. Usus Customer involvere Widget nos vis reficiendi

  1.             Consumer<CounterModel>(
  2.               builder: (context, counterModel, child) {
  3.                 return Row(
  4.                   mainAxisAlignment: MainAxisAlignment.spaceEvenly,
  5.                   children: [
  6.                     Text('计数器1个数: ${counterModel._counter1}'),
  7.                     ElevatedButton(onPressed: (){
  8.                       counterModel.addCounter1();
  9.                     }, child: const Icon(Icons.add),),
  10.                   ],
  11.                 );
  12.               },
  13.             ),

4. Integrum codicem talis est:

  1. import 'package:flutter/material.dart';
  2. import 'package:provider/provider.dart';
  3.  
  4. class ProviderRefreshPage extends StatefulWidget {
  5.   final String title;
  6.   const ProviderRefreshPage({super.key, required this.title});
  7.  
  8.   @override
  9.   State<ProviderRefreshPage> createState() => _ProviderRefreshPageState();
  10. }
  11.  
  12. class CounterModel extends ChangeNotifier {
  13.   int _counter1 = 0;
  14.   int _counter2 = 0;
  15.   void addCounter1(){
  16.     debugPrint('counter:$_counter1');
  17.     _counter1 += 1;
  18.     notifyListeners();
  19.   }
  20.   void addCounter2(){
  21.     debugPrint('counter:$_counter2');
  22.     _counter2 += 1;
  23.     notifyListeners();
  24.   }
  25. }
  26.  
  27. class _ProviderRefreshPageState extends State<ProviderRefreshPage> {
  28.  
  29.   @override
  30.   Widget build(BuildContext context) {
  31.     return Scaffold(
  32.       appBar: AppBar(
  33.         title: Text(widget.title),
  34.       ),
  35.       body: Center(
  36.         child: Column(
  37.           mainAxisAlignment: MainAxisAlignment.start,
  38.           children: <Widget>[
  39.             const SizedBox(height: 10,), // 添加一些间距
  40.             const Divider(),
  41.             const Text('计数器实例',style: TextStyle(fontSize: 12,fontWeight: FontWeight.bold),),
  42.             Consumer<CounterModel>(
  43.               builder: (context, counterModel, child) {
  44.                 return Row(
  45.                   mainAxisAlignment: MainAxisAlignment.spaceEvenly,
  46.                   children: [
  47.                     Text('计数器1个数: ${counterModel._counter1}'),
  48.                     ElevatedButton(onPressed: (){
  49.                       counterModel.addCounter1();
  50.                     }, child: const Icon(Icons.add),),
  51.                   ],
  52.                 );
  53.               },
  54.             ),
  55.  
  56.             Consumer<CounterModel>(
  57.               builder: (context, counterModel, child) {
  58.                 return Row(
  59.                   mainAxisAlignment: MainAxisAlignment.spaceEvenly,
  60.                   children: [
  61.                     Text('计数器1个数: ${counterModel._counter2}'),
  62.                     ElevatedButton(onPressed: (){
  63.                       counterModel.addCounter2();
  64.                     }, child: const Icon(Icons.add),),
  65.                   ],
  66.                 );
  67.               },
  68.             ),
  69.             const Divider(height: 20,),
  70.           ],
  71.         ),
  72.       ),
  73.     );
  74.   }
  75. }

6.GetX

GetX etiam uti possumus ad recreationem partialem UI efficiendam.

Primum GetX install:

get: ^4.6.6

Tunc encapsulabimus variabiles in GetxController.

  1. class CounterManagerController extends GetxController {
  2.   final counter1 = 0.obs;
  3.   final counter2 = 0.obs;
  4.   void incrementCount1() {
  5.     counter1.value++;
  6.   }
  7.   void incrementCount2() {
  8.     counter2.value++;
  9.   }
  10. }

Tum Obx utere ad involvere Widget quod logicam demonstrare debet.

Obx(()=&gt; Textus('Conter 1 numerus: ${controller.counter2.value}'))

Codicem integrum sic habet:

  1. import 'package:flutter/material.dart';
  2. import 'package:get/get.dart';
  3.  
  4.  
  5. class CounterManagerController extends GetxController {
  6.   final counter1 = 0.obs;
  7.   final counter2 = 0.obs;
  8.   void incrementCount1() {
  9.     counter1.value++;
  10.   }
  11.   void incrementCount2() {
  12.     counter2.value++;
  13.   }
  14. }
  15.  
  16. class GetXRefreshUIPage extends StatelessWidget {
  17.   final String title;
  18.   const GetXRefreshUIPage({super.key, required this.title});
  19.  
  20.   @override
  21.   Widget build(BuildContext context) {
  22.     final CounterManagerController controller = Get.put(CounterManagerController());
  23.     return Scaffold(
  24.       appBar: AppBar(
  25.         title: Text(title),
  26.       ),
  27.       body: Center(
  28.         child: Column(
  29.           mainAxisAlignment: MainAxisAlignment.start,
  30.           children: <Widget>[
  31.             const SizedBox(
  32.               height: 10,
  33.             ), // 添加一些间距
  34.             const Divider(),
  35.             const Text(
  36.               '计数器实例',
  37.               style: TextStyle(fontSize: 12, fontWeight: FontWeight.bold),
  38.             ),
  39.             Row(
  40.               mainAxisAlignment: MainAxisAlignment.spaceEvenly,
  41.               children: [
  42.                 Obx(()=> Text('计数器1个数: ${controller.counter1.value}')),
  43.                 ElevatedButton(
  44.                   onPressed: () {
  45.                     controller.incrementCount1();
  46.                   },
  47.                   child: const Icon(Icons.add),
  48.                 ),
  49.               ],
  50.             ),
  51.             Row(
  52.               mainAxisAlignment: MainAxisAlignment.spaceEvenly,
  53.               children: [
  54.                 Obx(()=> Text('计数器1个数: ${controller.counter2.value}')),
  55.                 ElevatedButton(
  56.                   onPressed: () {
  57.                     controller.incrementCount2();
  58.                   },
  59.                   child: const Icon(Icons.add),
  60.                 ),
  61.               ],
  62.             ),
  63.             const Divider(
  64.               height: 20,
  65.             ),
  66.           ],
  67.         ),
  68.       ),
  69.     );
  70.   }
  71. }

Nimirum plures aliae sunt modi ad reficiendum partiale refrigerium in GetX. Vide potes documenta eius. Hic est una idea exsecutionis.

7. Usus GlobalKey

Praemissae tres modi exsequendi omnes per compagem perficiuntur. Si hanc compagem importare non vis, GlobalKey possumus uti ad munus refectio partialis UI efficiendum.

Clavis unica per applicationem GlobalKey elementa singulariter agnoscit. GlobalKey aditum praebet elementis consociatae, utBuildContext .for*StatefulWidgets, GlobalKey etiam praebetStateObvius.

Nostris timentibus demo, si UI per GlobalKey ex parte reficimus, primum Widget exponimus ut in parte separata reficiatur et encapsuletur.

Integrum codicem hoc modo se habet. Nos encapsulamus Widget ut parte reficiatur et praebeat interfaciem ad notitias internas reficiendas, onPressed.

  1. class CounterText extends StatefulWidget {
  2.   const CounterText(Key key) : super(key: key);
  3.   @override
  4.   State<StatefulWidget> createState() {
  5.     return CounterTextState();
  6.   }
  7. }
  8.  
  9. class CounterTextState extends State<CounterText> {
  10.   String _text="0";
  11.  
  12.   @override
  13.   Widget build(BuildContext context) {
  14.     return Center(
  15.       child: Text(_text,style: const TextStyle(fontSize: 20),),
  16.     );
  17.   }
  18.   void onPressed(int count) {
  19.     setState(() {
  20.       _text = count.toString();
  21.     });
  22.   }
  23. }

Tunc instantiate GlobaKey in instrumento nostro principali;

  1.   int _count   = 0;
  2.   int _count2  = 0;
  3.   GlobalKey<CounterTextState> textKey = GlobalKey();
  4.   GlobalKey<CounterTextState> textKey2 = GlobalKey();

In eventu quem UI refici debet, vocant interfacem provisum priore gradu per GlobalKey et refice.

Codicem integrum sic habet:

  1. import 'package:flutter/material.dart';
  2.  
  3. class GlobalKeyRefreshPage extends StatefulWidget {
  4.   final String title;
  5.   const GlobalKeyRefreshPage({super.key, required this.title});
  6.  
  7.   @override
  8.   State<GlobalKeyRefreshPage> createState() => _GlobalKeyRefreshPageState();
  9. }
  10.  
  11. class _GlobalKeyRefreshPageState extends State<GlobalKeyRefreshPage> {
  12.   int _count   = 0;
  13.   int _count2  = 0;
  14. //包裹你定义的需要更新的weight
  15.   GlobalKey<CounterTextState> textKey = GlobalKey();
  16.   GlobalKey<CounterTextState> textKey2 = GlobalKey();
  17.  
  18.   @override
  19.   Widget build(BuildContext context) {
  20.     return Scaffold(
  21.       appBar: AppBar(
  22.         title:  Text(widget.title),
  23.       ),
  24.       body: Center(
  25.         child: Column(
  26.           mainAxisAlignment: MainAxisAlignment.start,
  27.           children: <Widget>[
  28.             const SizedBox(
  29.               height: 10,
  30.             ), // 添加一些间距
  31.             const Divider(),
  32.             const Text(
  33.               '计数器实例',
  34.               style: TextStyle(fontSize: 12, fontWeight: FontWeight.bold),
  35.             ),
  36.             Row(
  37.               mainAxisAlignment: MainAxisAlignment.spaceEvenly,
  38.               children: [
  39.                 CounterText(textKey),
  40.                 ElevatedButton(
  41.                   onPressed: () {
  42.                     _count++;
  43.                     textKey.currentState?.onPressed(_count);
  44.                   },
  45.                   child: const Icon(Icons.add),
  46.                 ),
  47.               ],
  48.             ),
  49.             Row(
  50.               mainAxisAlignment: MainAxisAlignment.spaceEvenly,
  51.               children: [
  52.                 CounterText(textKey2),
  53.                 ElevatedButton(
  54.                   onPressed: () {
  55.                     _count2++;
  56.                     textKey2.currentState?.onPressed(_count2);
  57.                   },
  58.                   child: const Icon(Icons.add),
  59.                 ),
  60.               ],
  61.             ),
  62.             const Divider(
  63.               height: 20,
  64.             ),
  65.           ],
  66.         ),
  67.       ),
  68.     );
  69.   }
  70. }
  71.  
  72.  
  73. class CounterText extends StatefulWidget {
  74.   const CounterText(Key key) : super(key: key);
  75.   @override
  76.   State<StatefulWidget> createState() {
  77.     return CounterTextState();
  78.   }
  79. }
  80.  
  81. class CounterTextState extends State<CounterText> {
  82.   String _text="0";
  83.  
  84.   @override
  85.   Widget build(BuildContext context) {
  86.     return Center(
  87.       child: Text(_text,style: const TextStyle(fontSize: 20),),
  88.     );
  89.   }
  90.   void onPressed(int count) {
  91.     setState(() {
  92.       _text = count.toString();
  93.     });
  94.   }
  95. }

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