Flutter路由自动生成插件shelf_router_generator的使用

简介

shelf_router_generator 是一个用于 Dart 的代码生成器，它使得通过注解（annotations）来自动生成 shelf_route.Router 变得简单。这个工具依赖于 Shelf 和 shelf_router，可以让你更方便地构建基于 Shelf 的 Web 应用程序。

为了使用 shelf_router_generator，你需要将其作为开发依赖项添加到你的项目中，并确保你已经安装了 build_runner。以下是具体的配置方法和一个完整的示例demo。

安装与配置

在你的 pubspec.yaml 文件中添加以下依赖：

dependencies:
  shelf: ^0.7.5
  shelf_router: ^0.7.0+1

dev_dependencies:
  shelf_router_generator: ^0.7.0+1
  build_runner: ^1.3.1

然后运行以下命令来获取依赖项：

flutter pub get

示例代码

下面是一个完整的示例，展示了如何使用 shelf_router_generator 来定义路由并生成相应的代码。

main.dart

import 'dart:async' show Future;

import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart' as shelf_io;
import 'package:shelf_router/shelf_router.dart';

// Generated code will be written to 'main.g.dart'
part 'main.g.dart';

class Service {
  // A handler is annotated with @Route.<verb>('<route>'), the '<route>' may
  // embed URL-parameters, and these may be taken as parameters by the handler.
  // But either all URL-parameters or none of the URL parameters must be taken
  // as parameters by the handler.
  @Route.get('/say-hi/<name>')
  Response _hi(Request request, String name) => Response.ok('hi $name');

  // Embedded URL parameters may also be associated with a regular-expression
  // that the pattern must match.
  @Route.get('/user/<userId|[0-9]+>')
  Response _user(Request request, String userId) =>
      Response.ok('User has the user-number: $userId');

  // Handlers can be asynchronous (returning `FutureOr` is also allowed).
  @Route.get('/wave')
  Future<Response> _wave(Request request) async {
    await Future<void>.delayed(const Duration(milliseconds: 100));
    return Response.ok('_o/');
  }

  // Other routers can be mounted...
  @Route.mount('/api')
  Router get _api => Api().router;

  // You can catch all verbs and use a URL-parameter with a regular expression
  // that matches everything to catch app.
  @Route.all('/<ignored|.*>')
  Response _notFound(Request request) => Response.notFound('Page not found');

  // The generated function _$ServiceRouter can be used to get a [Handler]
  // for this object. This can be used with [shelf_io.serve].
  Handler get handler => _$ServiceRouter(this).call;
}

class Api {
  // A handler can have more than one route :)
  @Route.get('/messages')
  @Route.get('/messages/')
  Future<Response> _messages(Request request) async => Response.ok('[]');

  // This nested catch-all, will only catch /api/.* when mounted above.
  // Notice that ordering if annotated handlers and mounts is significant.
  @Route.all('/<ignored|.*>')
  Response _notFound(Request request) => Response.notFound('null');

  // The generated function _$ApiRouter can be used to expose a [Router] for
  // this object.
  Router get router => _$ApiRouter(this);
}

// Run shelf server and host a [Service] instance on port 8080.
void main() async {
  final service = Service();
  final server = await shelf_io.serve(service.handler, 'localhost', 8080);
  print('Server running on localhost:${server.port}');
}

生成代码

确保你在项目根目录下运行以下命令以生成代码：

flutter pub run build_runner build

这将会根据你在 main.dart 中定义的注解生成 main.g.dart 文件，其中包含了路由逻辑。

总结

通过 shelf_router_generator，你可以轻松地为基于 Shelf 的 Web 应用程序创建和管理路由。只需通过简单的注解方式定义路由，然后使用 build_runner 自动生成路由代码即可。希望这个示例能够帮助你更好地理解和使用 shelf_router_generator。如果有任何问题或需要进一步的帮助，请随时提问！