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网页游戏排行榜2020排行榜,seo在哪可以学,利用h5网站做app,网站维护的注意事项文章目录 5. 网络请求核心库5.1 http5.2 dio 必须掌握5.3 GET/POST 请求5.4 JSON 序列化与反序列化（json_serializable）5.5 错误处理与加载状态管理总结 5. 网络请求网络请求是移动应用开发中不可或缺的一部分，Flutter 提供了多种方式来实…

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文章目录

- - 5. 网络请求
  - 核心库
  - - 5.1 `http`
    - 5.2 `dio`
  - 必须掌握
  - - 5.3 GET/POST 请求
    - 5.4 JSON 序列化与反序列化（`json_serializable`）
    - 5.5 错误处理与加载状态管理
  - 总结

5. 网络请求

网络请求是移动应用开发中不可或缺的一部分，Flutter 提供了多种方式来实现网络请求。掌握网络请求的核心库和技巧，可以帮助你高效地与后端 API 交互。

核心库

5.1 `http`

特点：Flutter 官方提供的轻量级网络请求库。
安装：
```
dependencies:http: ^0.13.3
```

5.2 `dio`

特点：功能强大的第三方网络请求库，支持拦截器、文件上传、请求取消等高级功能。
安装：
```
dependencies:dio: ^4.0.0
```

必须掌握

5.3 GET/POST 请求

使用 http 库：

import 'package:http/http.dart' as http;// GET 请求
Future<void> fetchData() async {final response = await http.get(Uri.parse('https://jsonplaceholder.typicode.com/posts/1'));if (response.statusCode == 200) {print('Response data: ${response.body}');} else {print('Request failed with status: ${response.statusCode}');}
}// POST 请求
Future<void> postData() async {final response = await http.post(Uri.parse('https://jsonplaceholder.typicode.com/posts'),body: {'title': 'foo', 'body': 'bar', 'userId': '1'},);if (response.statusCode == 201) {print('Response data: ${response.body}');} else {print('Request failed with status: ${response.statusCode}');}
}

使用 dio 库：

import 'package:dio/dio.dart';final dio = Dio();// GET 请求
Future<void> fetchData() async {final response = await dio.get('https://jsonplaceholder.typicode.com/posts/1');if (response.statusCode == 200) {print('Response data: ${response.data}');} else {print('Request failed with status: ${response.statusCode}');}
}// POST 请求
Future<void> postData() async {final response = await dio.post('https://jsonplaceholder.typicode.com/posts',data: {'title': 'foo', 'body': 'bar', 'userId': '1'},);if (response.statusCode == 201) {print('Response data: ${response.data}');} else {print('Request failed with status: ${response.statusCode}');}
}

5.4 JSON 序列化与反序列化（`json_serializable`）

手动序列化：

class Post {final int userId;final int id;final String title;final String body;Post({required this.userId, required this.id, required this.title, required this.body});factory Post.fromJson(Map<String, dynamic> json) {return Post(userId: json['userId'],id: json['id'],title: json['title'],body: json['body'],);}Map<String, dynamic> toJson() {return {'userId': userId,'id': id,'title': title,'body': body,};}
}

使用 json_serializable：

添加依赖：

dependencies:json_annotation: ^4.4.0dev_dependencies:build_runner: ^2.1.4json_serializable: ^6.1.4

定义模型类：

import 'package:json_annotation/json_annotation.dart';part 'post.g.dart';@JsonSerializable()
class Post {final int userId;final int id;final String title;final String body;Post({required this.userId, required this.id, required this.title, required this.body});factory Post.fromJson(Map<String, dynamic> json) => _$PostFromJson(json);Map<String, dynamic> toJson() => _$PostToJson(this);
}

生成代码：
运行以下命令生成序列化代码：
```
flutter pub run build_runner build
```

使用模型类：

Future<Post> fetchPost() async {final response = await http.get(Uri.parse('https://jsonplaceholder.typicode.com/posts/1'));if (response.statusCode == 200) {return Post.fromJson(jsonDecode(response.body));} else {throw Exception('Failed to load post');}
}

5.5 错误处理与加载状态管理

错误处理：

Future<void> fetchData() async {try {final response = await dio.get('https://jsonplaceholder.typicode.com/posts/1');if (response.statusCode == 200) {print('Response data: ${response.data}');} else {throw Exception('Request failed with status: ${response.statusCode}');}} catch (e) {print('Error: $e');}
}

加载状态管理：

class DataProvider with ChangeNotifier {bool isLoading = false;String data = '';Future<void> fetchData() async {isLoading = true;notifyListeners();try {final response = await http.get(Uri.parse('https://jsonplaceholder.typicode.com/posts/1'));if (response.statusCode == 200) {data = response.body;} else {throw Exception('Request failed with status: ${response.statusCode}');}} catch (e) {print('Error: $e');} finally {isLoading = false;notifyListeners();}}
}