Flutter状态管理插件hooks_riverpod的使用

介绍

Riverpod 是一个响应式的缓存和数据绑定框架，它简化了与异步代码的工作。它通过以下方式来提升开发体验：

• 默认处理错误/加载状态。无需手动捕获错误。
• 原生支持高级场景，如下拉刷新。
• 将逻辑从UI中分离出来。
• 确保代码可测试、可扩展且可重用。

包名	版本
riverpod
flutter_riverpod
hooks_riverpod

更多关于 Riverpod 的信息，请访问 官方网站。

使用示例

定义网络请求

@riverpod
Future<String> boredSuggestion(Ref ref) async {
  final response = await http.get(
    Uri.https('boredapi.com', '/api/activity'),
  );
  final json = jsonDecode(response.body);
  return json['activity']! as String;
}

监听网络请求并在UI中处理结果

class Home extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final boredSuggestion = ref.watch(boredSuggestionProvider);
    // Perform a switch-case on the result to handle loading/error states
    return switch (boredSuggestion) {
      AsyncData(:final value) => Text('data: $value'),
      AsyncError(:final error) => Text('error: $error'),
      _ => const Text('loading'),
    };
  }
}

完整示例：计数器应用

这是一个完整的示例，展示了如何使用 hooks_riverpod 创建一个简单的计数器应用程序。

主文件 main.dart

import 'package:flutter/material.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';

void main() {
  runApp(
    /// [MyApp] is wrapped in a [ProviderScope].
    /// This widget is where the state of most of our providers will be stored.
    /// This replaces `MultiProvider` if you've used `provider` before.
    const ProviderScope(
      child: MyApp(),
    ),
  );
}

/// A provider that creates and listen to a [StateNotifier].
///
/// Providers are declared as global variables.
/// This does not hinder testability, as the state of a provider is instead
/// stored inside a [ProviderScope].
final counterProvider = StateNotifierProvider<Counter, int>((_) => Counter());

/// A simple [StateNotifier] that implements a counter.
///
/// It doesn't have to be a [StateNotifier], and could be anything else such as:
/// - [ChangeNotifier], with [ChangeNotifierProvider]
/// - [Stream], with [StreamProvider]
/// ...
class Counter extends StateNotifier<int> {
  Counter() : super(0);

  void increment() => state++;
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends HookConsumerWidget {
  const MyHomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Riverpod counter example'),
      ),
      body: Center(
        // HookConsumer is a builder widget that allows you to read providers and utilise hooks.
        child: HookConsumer(
          builder: (context, ref, _) {
            final count = ref.watch(counterProvider);

            return Text(
              '$count',
              style: Theme.of(context).textTheme.headlineMedium,
            );
          },
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => ref.read(counterProvider.notifier).increment(),
        child: const Icon(Icons.add),
      ),
    );
  }
}

总结

hooks_riverpod 提供了一种强大的状态管理解决方案，适用于各种复杂的应用场景。通过定义提供者（Provider），我们可以轻松地将业务逻辑与UI分离，并确保代码的可维护性和可测试性。上述示例展示了如何创建一个简单的计数器应用，希望对您有所帮助！