Flutter资源限制插件shelf_limiter的使用

shelf_limiter 是一个用于 Dart 中 Shelf 库的强大且高度可定制的中间件包，能够实现高效的速率限制。通过简单的设置保护你的 API 免受滥用并确保公平使用。

🌟 特性

安装

在 pubspec.yaml 文件中添加 shelf_limiter：

dependencies:
  shelf_limiter: <latest>

然后运行：

dart pub get

或者简单地运行：

dart pub add shelf_limiter

使用

🔧 基本用法

快速有效地在 Shelf 应用程序中实现速率限制。以下是使用 shelfLimiter 中间件的基本示例：

import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart' as io;
import 'package:shelf_limiter/shelf_limiter.dart';

void main() async {
  final limiter = shelfLimiter(
    RateLimiterOptions(
      maxRequests: 5,
      windowSize: const Duration(minutes: 1),
    ),
  );

  final handler =
      const Pipeline().addMiddleware(limiter).addHandler(_echoRequest);

  var server = await io.serve(handler, 'localhost', 8080);
  print('Server listening on port ${server.port}');
}

Response _echoRequest(Request request) => Response.ok('Request received');

在这个示例中，任何客户端每分钟最多只能发出 5 次请求。如果客户端超过此限制，他们将收到 429 Too Many Requests 响应。

🛠️ 增强 API 的自定义头部

使用自定义头部增强响应：

import 'dart:convert';
import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart' as io;
import 'package:shelf_limiter/shelf_limiter.dart';

void main() async {
  final options = RateLimiterOptions(
    headers: {
      'X-Custom-Header': 'Rate limited',
    },
  );

  final limiter = shelfLimiter(
    RateLimiterOptions(
      maxRequests: 5,
      windowSize: const Duration(minutes: 1),
      headers: options.headers,
    ),
  );

  final handler =
      const Pipeline().addMiddleware(limiter).addHandler(_echoRequest);

  var server = await io.serve(handler, 'localhost', 8080);
  print('Server listening on port ${server.port}');
}

Response _echoRequest(Request request) => Response.ok('Request received');

💡 自定义速率限制超限响应

当速率限制被超出时，提供有意义的反馈：

import 'dart:convert';
import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart' as io;
import 'package:shelf_limiter/shelf_limiter.dart';

void main() async {
  final options = RateLimiterOptions(
    headers: {
      'X-Custom-Header': 'Rate limited',
    },
    onRateLimitExceeded: (request) async {
      return Response(
        429,
        body: jsonEncode({
          'status': false,
          'message': "Uh, hm! Wait a minute, that's a lot of requests.",
        }),
        headers: {
          'Content-Type': 'application/json',
        },
      );
    },
  );

  final limiter = shelfLimiter(
    RateLimiterOptions(
      maxRequests: 5,
      windowSize: const Duration(minutes: 1),
      headers: options.headers,
      onRateLimitExceeded: options.onRateLimitExceeded,
    ),
  );

  final handler =
      const Pipeline().addMiddleware(limiter).addHandler(_echoRequest);

  var server = await io.serve(handler, 'localhost', 8080);
  print('Server listening on port ${server.port}');
}

Response _echoRequest(Request request) => Response.ok('Request received');

📌 高级用法与端点特定限制

当您希望微调速率限制策略并避免一刀切的方法时，shelfLimiterByEndpoint 是您最好的朋友。这个中间件允许您为不同的端点设置独特的速率限制，使您能够根据每个路由的需求量身定制限制。

示例 - 不同路由的自定义限制

以下是如何使用 shelfLimiterByEndpoint 使您的 API 如同一台运转良好的机器：

import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart' as io;
import 'package:shelf_limiter/shelf_limiter.dart';

void main() async {
  final limiter = shelfLimiterByEndpoint(
    endpointLimits: {
      '/auth': RateLimiterOptions(
        maxRequests: 5,
        windowSize: const Duration(minutes: 1),
      ),
      '/data': RateLimiterOptions(
        maxRequests: 20,
        windowSize: const Duration(minutes: 1),
      ),
      '/api/v1/*': RateLimiterOptions( // Wildcard path matching
        maxRequests: 15,
        windowSize: const Duration(minutes: 2),
      ),
    },
    defaultOptions: RateLimiterOptions(
      maxRequests: 100,
      windowSize: const Duration(minutes: 1),
    ),
  );

  final handler =
      const Pipeline().addMiddleware(limiter).addHandler(_echoRequest);

  var server = await io.serve(handler, 'localhost', 8080);
  print('Server listening on port ${server.port}');
}

Response _echoRequest(Request request) => Response.ok('Request received');