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最近在忙于 Fireasy 的重构,3.x 抛弃了 .Net Framework 时代的一些思想和模式,紧密拥抱 .Net Core,但它的思想仍然是开放性和灵活性。今天我主要来说说依赖注入与服务发现。
.Net Core 有自己的一套依赖注入,它的容器暴露给 IServiceCollection,通过在里面放入一些单例(Singleton)、瞬时(Transient)、作用域(Scoped)的一些服务描述(服务与实现的关系映射),这一部分我就不再细说了。
当然,一般常用的方式是,通过 AddSingleton、AddTransient 和 AddScoped 方法往容器里面加,但如果是依赖比较多的情况下(比如业务服务类),那你可能会经常忘了写这一部分代码了,而且也很难于维护。如常见的方式:- void ConfigureServices(IServiceCollection services)
- {
- services.AddTransient<IDeptmentService, DeptmentService>();
- services.AddTransient<IRoleService, RoleService>();
- services.AddTransient<IUserService, UserService>();
- services.AddTransient<IDataRoleService, DataRoleService>();
- //.......
- services.AddTransient<IProcessService, ProcessService>();
- services.AddTransient<IWorkService, WorkService>();
- }
复制代码 有没有更简便更容易维护的方式呢?答案是当然有!
在 Fireasy,我们定义了三个服务接口,分别是 ISingletonService、ITransientService 和 IScopedService,这三个类只是一个标识,没有具体的方法和属性。使用需要注入的类实现此接口,如下:- public class DeptmentService : IDeptmentService, ITransientService
- {
- // ......
- }
- public class DataRoleHelper : IDataRoleHelper, ISingletonService
- {
- // ......
- }
复制代码 好了,你只需在 ConfigureServices 里添加上这么一行代码,就能实现依赖注入:- void ConfigureServices(IServiceCollection services)
- {
- services.AddFireasy();
- }
复制代码 现在开始步入正题了,来看看 AddFireasy 是如何工作的。
IServiceDiscoverer 是用于服务发现的接口,它的默认实现是 DefaultServiceDiscoverer。如下:- public static SetupBuilder AddFireasy(this IServiceCollection services, Action<SetupOptions>? configure = null)
- {
- var options = new SetupOptions();
- configure?.Invoke(options);
- var builder = new SetupBuilder(services, options);
- var discoverer = options.DiscoverOptions.DiscovererFactory == null ? new DefaultServiceDiscoverer(services, options.DiscoverOptions)
- : options.DiscoverOptions.DiscovererFactory(services, options.DiscoverOptions);
- if (discoverer != null)
- {
- services.AddSingleton<IServiceDiscoverer>(discoverer);
- }
- return builder;
- }
复制代码 入口方法是 DiscoverServices,它会遍列程序目录下的所有程序集文件(*.dll),这里有程序集过滤器,你可以自己定义过滤规则。如下:- /// <summary>
- /// 发现工作目录中所有程序集中的依赖类型。
- /// </summary>
- /// <param name="services"></param>
- private void DiscoverServices(IServiceCollection services)
- {
- foreach (var assembly in GetAssemblies())
- {
- if (_options?.AssemblyFilters?.Any(s => s.IsFilter(assembly)) == true)
- {
- continue;
- }
- if (_options?.AssemblyFilterPredicates?.Any(s => s(assembly)) == true)
- {
- continue;
- }
- _assemblies.Add(assembly);
- ConfigureServices(services, assembly);
- DiscoverServices(services, assembly);
- }
- }
复制代码 方法 DiscoverServices 用于对单个程序集进行服务发现并进行注册,这里同样也有类型过滤器,如下:- /// <summary>
- /// 发现程序集中的所有依赖类型。
- /// </summary>
- /// <param name="services"></param>
- /// <param name="assembly"></param>
- private void DiscoverServices(IServiceCollection services, Assembly assembly)
- {
- foreach (var type in assembly.GetExportedTypes())
- {
- if (_options?.TypeFilters?.Any(s => s.IsFilter(assembly, type)) == true)
- {
- continue;
- }
- if (_options?.TypeFilterPredicates?.Any(s => s(assembly, type)) == true)
- {
- continue;
- }
- ServiceLifetime? lifetime;
- var interfaceTypes = type.GetDirectImplementInterfaces().ToArray();
- //如果使用标注
- if (type.IsDefined(typeof(ServiceRegisterAttribute)))
- {
- lifetime = type.GetCustomAttribute<ServiceRegisterAttribute>()!.Lifetime;
- }
- else
- {
- lifetime = GetLifetimeFromType(type);
- }
- if (lifetime == null)
- {
- continue;
- }
- if (interfaceTypes.Length > 0)
- {
- interfaceTypes.ForEach(s => AddService(services, s, type, (ServiceLifetime)lifetime));
- }
- else
- {
- AddService(services, type, type, (ServiceLifetime)lifetime);
- }
- }
- }
- private ServiceLifetime? GetLifetimeFromType(Type type)
- {
- if (typeof(ISingletonService).IsAssignableFrom(type))
- {
- return ServiceLifetime.Singleton;
- }
- else if (typeof(ITransientService).IsAssignableFrom(type))
- {
- return ServiceLifetime.Transient;
- }
- else if (typeof(IScopedService).IsAssignableFrom(type))
- {
- return ServiceLifetime.Scoped;
- }
- return null;
- }
- private ServiceDescriptor AddService(IServiceCollection services, Type serviceType, Type implType, ServiceLifetime lifetime)
- {
- var descriptor = ServiceDescriptor.Describe(serviceType, implType, lifetime);
- _descriptors.Add(descriptor);
- services.Add(descriptor);
- return descriptor;
- }
复制代码 从上面的代码中可看出,通过在程序集内部查找实现了 ISingletonService、ITransientService 或 IScopedService 的类,并将它们添加到 services 中,这样就完成了开篇提到的工作。
这里还出现了一个 ServiceRegisterAttribute,它在不实现以上三个接口的情况下,通过标注 Lifetime 生命周期来进行注册,一样达到了目的。
接下来做几个简单的单元测试。
单例测试:- /// <summary>
- /// 测试单例服务
- /// </summary>
- [TestMethod]
- public void TestSingletonService()
- {
- var services = new ServiceCollection();
- var builder = services.AddFireasy();
- var serviceProvider = services.BuildServiceProvider();
- var service1 = serviceProvider.GetService<ITestSingletonService>();
- var service2 = serviceProvider.GetService<ITestSingletonService>();
- Assert.IsNotNull(service1);
- Assert.IsNotNull(service2);
- //两对象的id应相等
- Assert.AreEqual(service1.Id, service2.Id);
- }
- public interface ITestSingletonService
- {
- Guid Id { get; }
- void Test();
- }
- public class TestSingletonServiceImpl : ITestSingletonService, ISingletonService
- {
- public TestSingletonServiceImpl()
- {
- Id = Guid.NewGuid();
- }
- public Guid Id { get; }
- public void Test() => Console.WriteLine("Hello TestSingletonService!");
- }
复制代码 瞬时测试:- /// <summary>
- /// 测试瞬时服务
- /// </summary>
- [TestMethod]
- public void TestTransientService()
- {
- var services = new ServiceCollection();
- var builder = services.AddFireasy();
- var serviceProvider = services.BuildServiceProvider();
- var service1 = serviceProvider.GetService<ITestTransientService>();
- var service2 = serviceProvider.GetService<ITestTransientService>();
- Assert.IsNotNull(service1);
- Assert.IsNotNull(service2);
- //两对象的id应不相等
- Assert.AreNotEqual(service1.Id, service2.Id);
- }
- public interface ITestTransientService
- {
- Guid Id { get; }
- void Test();
- }
- public class TestTransientServiceImpl : ITestTransientService, ITransientService
- {
- public TestTransientServiceImpl()
- {
- Id = Guid.NewGuid();
- }
- public Guid Id { get; }
- public void Test() => Console.WriteLine("Hello TestTransientService!");
- }
复制代码 作用域测试:- /// <summary>
- /// 测试作用域服务
- /// </summary>
- [TestMethod]
- public void TestScopedService()
- {
- var services = new ServiceCollection();
- var builder = services.AddFireasy();
- var serviceProvider = services.BuildServiceProvider();
- Guid id1, id2;
- //作用域1
- using (var scope1 = serviceProvider.CreateScope())
- {
- var service1 = scope1.ServiceProvider.GetService<ITestScopedService>();
- var service2 = scope1.ServiceProvider.GetService<ITestScopedService>();
- Assert.IsNotNull(service1);
- Assert.IsNotNull(service2);
- //两对象的id应相等
- Assert.AreEqual(service1.Id, service2.Id);
- id1 = service1.Id;
- }
- //作用域2
- using (var scope2 = serviceProvider.CreateScope())
- {
- var service1 = scope2.ServiceProvider.GetService<ITestScopedService>();
- var service2 = scope2.ServiceProvider.GetService<ITestScopedService>();
- Assert.IsNotNull(service1);
- Assert.IsNotNull(service2);
- //两对象的id应相等
- Assert.AreEqual(service1.Id, service2.Id);
- id2 = service1.Id;
- }
- //两次scoped的id应不相等
- Assert.AreNotEqual(id1, id2);
- }
- public interface ITestScopedService
- {
- Guid Id { get; }
- void Test();
- }
- public class TestScopedServiceImpl : ITestScopedService, IScopedService
- {
- public TestScopedServiceImpl()
- {
- Id = Guid.NewGuid();
- }
- public Guid Id { get; }
- public void Test() => Console.WriteLine("Hello TestScopedService!");
- }
复制代码 可见,不需要显式 Add 也能将大量的服务类注入到容器中,不仅节省了大量的时间和代码,更是提高了程序的可维护性。
最后,奉上 Fireasy 3 的开源地址:https://gitee.com/faib920/fireasy3 ,欢迎大家前来捧场。
本文相关代码请参考 https://gitee.com/faib920/fireasy3/src/libraries/Fireasy.Common/DependencyInjection 下的相关文件。
来源:https://www.cnblogs.com/fireasy/archive/2023/03/01/17170417.html
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