Flutter Networking

Quick Start

Add HTTP dependency to pubspec.yaml:

dependencies:
  http: ^1.6.0

Basic GET request:

import 'package:http/http.dart' as http;
import 'dart:convert';

Future<Album> fetchAlbum() async {
  final response = await http.get(
    Uri.parse('https://api.example.com/albums/1'),
  );

  if (response.statusCode == 200) {
    return Album.fromJson(jsonDecode(response.body));
  } else {
    throw Exception('Failed to load album');
  }
}

Use in UI with FutureBuilder:

FutureBuilder<Album>(
  future: futureAlbum,
  builder: (context, snapshot) {
    if (snapshot.hasData) {
      return Text(snapshot.data!.title);
    } else if (snapshot.hasError) {
      return Text('${snapshot.error}');
    }
    return const CircularProgressIndicator();
  },
)

HTTP Methods

GET - Fetch Data

Use for retrieving data. See http-basics.md for complete examples.

POST - Create Data

Use for creating new resources. Requires Content-Type: application/json header.

final response = await http.post(
  Uri.parse('https://api.example.com/albums'),
  headers: <String, String>{
    'Content-Type': 'application/json; charset=UTF-8',
  },
  body: jsonEncode(<String, String>{'title': title}),
);

See http-basics.md for POST examples.

PUT - Update Data

Use for updating existing resources.

final response = await http.put(
  Uri.parse('https://api.example.com/albums/1'),
  headers: <String, String>{
    'Content-Type': 'application/json; charset=UTF-8',
  },
  body: jsonEncode(<String, String>{'title': title}),
);

DELETE - Remove Data

Use for deleting resources.

final response = await http.delete(
  Uri.parse('https://api.example.com/albums/1'),
  headers: <String, String>{
    'Content-Type': 'application/json; charset=UTF-8',
  },
);

WebSocket

Add WebSocket dependency:

dependencies:
  web_socket_channel: ^3.0.3

Basic WebSocket connection:

import 'package:web_socket_channel/web_socket_channel.dart';

final _channel = WebSocketChannel.connect(
  Uri.parse('wss://echo.websocket.events'),
);

// Listen for messages
StreamBuilder(
  stream: _channel.stream,
  builder: (context, snapshot) {
    return Text(snapshot.hasData ? '${snapshot.data}' : '');
  },
)

// Send message
_channel.sink.add('Hello');

// Close connection
_channel.sink.close();

See websockets.md for complete WebSocket implementation.

Authentication

Add authorization headers to requests:

import 'dart:io';

final response = await http.get(
  Uri.parse('https://api.example.com/data'),
  headers: {HttpHeaders.authorizationHeader: 'Bearer $token'},
);

Common authentication patterns:

• Bearer Token: Authorization: Bearer <token>
• Basic Auth: Authorization: Basic <base64_credentials>
• API Key: X-API-Key: <key>

See authentication.md for detailed authentication strategies.

Error Handling

Handle HTTP errors appropriately:

if (response.statusCode >= 200 && response.statusCode < 300) {
  return Data.fromJson(jsonDecode(response.body));
} else if (response.statusCode == 401) {
  throw UnauthorizedException();
} else if (response.statusCode == 404) {
  throw NotFoundException();
} else {
  throw ServerException();
}

See error-handling.md for comprehensive error handling strategies.

Performance

Background Parsing with Isolates

For large JSON responses, use compute() to parse in background isolate:

import