传统的依赖注入确实简单,但是随着项目的扩展随之而来的问题又来了,因为传统的注入是单个类和接口注入的,加入项目的接口和类增加到了上百个的话,就需要在Startup.cs中复制注入上百次,虽然能解决问题,但是显然有点笨拙。
下面介绍一个程序集DI依赖注入,即通过反射进行文件注入
首先通过反射获取当前程序集
/// <summary>/// 通过程序集的名称加载程序集/// </summary>/// <param name="assemblyName"></param>/// <returns></returns>public static Assembly GetAssemblyByName(string assemblyName){return AssemblyLoadContext.Default.LoadFromAssemblyName(new AssemblyName(assemblyName));}
程序集依赖注入方法,逻辑不多描述,全在注释中
/// <summary>/// 程序集依赖注入/// </summary>/// <param name="services">服务实例</param>/// <param name="assemblyName">程序集名称。不带DLL</param>/// <param name="serviceLifetime">依赖注入的类型 可为空</param>public static void AddAssembly(this IServiceCollection services, string assemblyName, ServiceLifetime serviceLifetime = ServiceLifetime.Scoped){if (services == null)throw new ArgumentNullException(nameof(services) + "为空");if (String.IsNullOrEmpty(assemblyName))throw new ArgumentNullException(nameof(assemblyName) + "为空");var assembly = RuntimeHelper.GetAssemblyByName(assemblyName);if (assembly == null)throw new DllNotFoundException(nameof(assembly) + ".dll不存在");//找到当前程序集的类集合var types = assembly.GetTypes();//过滤筛选(是类文件,并且不是抽象类,不是泛型)var list = types.Where(o => o.IsClass && !o.IsAbstract && !o.IsGenericType).ToList();if (list == null && !list.Any())return;//遍历获取到的类foreach (var type in list){//然后获取到类对应的接口var interfacesList = type.GetInterfaces();//校验接口存在则继续if (interfacesList == null || !interfacesList.Any())continue;//获取到接口(第一个)var inter = interfacesList.First();switch (serviceLifetime){//根据条件,选择注册依赖的方法case ServiceLifetime.Scoped://将获取到的接口和类注册进去 services.AddScoped(inter, type);break;case ServiceLifetime.Singleton:services.AddScoped(inter, type);break;case ServiceLifetime.Transient:services.AddTransient(inter, type);break;}}}
具体在Startup.cs 中调用如下
//程序集依赖注入(General.Services程序集名称) services.AddAssembly("General.Services");