前言

在asp.net core中，我巨硬引入了DI容器，我们可以在不使用第三方插件的情况下轻松实现依赖注入。如下代码：

1 // This method gets called by the runtime. Use this method to add services to the container. 2         public void ConfigureServices(IServiceCollection services) 3         { 4             //services.RegisterAssembly("IServices"); 5             services.AddSingleton
       
        (); 6             // Add framework services. 7             services.AddMvc(); 8             services.AddMvcCore() 9                 .AddApiExplorer();10             services.AddSwaggerGen(options =>11             {12                 options.SwaggerDoc("v1", new Info()13                 {14                     Title = "Swagger测试",15                     Version = "v1",16                     Description = "Swagger测试RESTful API ",17                     TermsOfService = "None",18                     Contact = new Contact19                     {20                         Name = "来来吹牛逼",21                         Email = "xxoo123@outlook.com"22                     },23                 });24                 //设置xml注释文档，注意名称一定要与项目名称相同25                 var filePath = Path.Combine(PlatformServices.Default.Application.ApplicationBasePath, "WebApi.xml");26                 options.IncludeXmlComments(filePath);27             });28         }

但是，随着公司业务的扩大，系统项目的功能模块急剧扩张，新增了不下百个或者千个Repository和Service（有点夸张了...），这时候如此单纯滴注入就有点操蛋了。

打懒主意

我可不可以通过反射技术来实现对程序集的注入呢？？

试试就试试

首先，我私自先制定一些类名的约束。规则嘛，反正是自己定。比如：

UserService --> IUserService

UserRepository --> IUserRepository

......

ClassName --> IClassName

好了，我们下面开始编码：

1 ///  2     /// IServiceCollection扩展 3     /// 
 4     public static class ServiceExtension 5     { 6         ///  7         /// 用DI批量注入接口程序集中对应的实现类。 8         /// 
        
          9         /// 需要注意的是，这里有如下约定：10         /// IUserService --> UserService, IUserRepository --> UserRepository.11         /// 
        12         /// 
13         /// 14         /// 接口程序集的名称（不包含文件扩展名）15         /// 
       16         public static IServiceCollection RegisterAssembly(this IServiceCollection service, string interfaceAssemblyName)17         {18             if (service == null)19                 throw new ArgumentNullException(nameof(service));20             if (string.IsNullOrEmpty(interfaceAssemblyName))21                 throw new ArgumentNullException(nameof(interfaceAssemblyName));22 23             var assembly = RuntimeHelper.GetAssembly(interfaceAssemblyName);24             if (assembly == null)25             {26                 throw new DllNotFoundException($"the dll \"{interfaceAssemblyName}\" not be found");27             }28 29             //过滤掉非接口及泛型接口30             var types = assembly.GetTypes().Where(t => t.GetTypeInfo().IsInterface && !t.GetTypeInfo().IsGenericType);31 32             foreach (var type in types)33             {34                 var implementTypeName = type.Name.Substring(1);35                 var implementType = RuntimeHelper.GetImplementType(implementTypeName, type);36                 if (implementType != null)37                     service.AddSingleton(type, implementType);38             }39             return service;40         }41 42         /// 43         /// 用DI批量注入接口程序集中对应的实现类。44         /// 
45         /// 46         /// 接口程序集的名称（不包含文件扩展名）47         /// 实现程序集的名称（不包含文件扩展名）48         /// 
       49         public static IServiceCollection RegisterAssembly(this IServiceCollection service, string interfaceAssemblyName, string implementAssemblyName)50         {51             if (service == null)52                 throw new ArgumentNullException(nameof(service));53             if(string.IsNullOrEmpty(interfaceAssemblyName))54                 throw new ArgumentNullException(nameof(interfaceAssemblyName));55             if (string.IsNullOrEmpty(implementAssemblyName))56                 throw new ArgumentNullException(nameof(implementAssemblyName));57 58             var interfaceAssembly = RuntimeHelper.GetAssembly(interfaceAssemblyName);59             if (interfaceAssembly == null)60             {61                 throw new DllNotFoundException($"the dll \"{interfaceAssemblyName}\" not be found");62             }63 64             var implementAssembly = RuntimeHelper.GetAssembly(implementAssemblyName);65             if (implementAssembly == null)66             {67                 throw new DllNotFoundException($"the dll \"{implementAssemblyName}\" not be found");68             }69 70             //过滤掉非接口及泛型接口71             var types = interfaceAssembly.GetTypes().Where(t => t.GetTypeInfo().IsInterface && !t.GetTypeInfo().IsGenericType);72 73             foreach (var type in types)74             {75                 //过滤掉抽象类、泛型类以及非class76                 var implementType = implementAssembly.DefinedTypes77                     .FirstOrDefault(t => t.IsClass && !t.IsAbstract && !t.IsGenericType &&78                                          t.GetInterfaces().Any(b => b.Name == type.Name));79                 if (implementType != null)80                 {81                     service.AddSingleton(type, implementType.AsType());82                 }83             }84 85             return service;86         }87     }

附上RuntimeHelper.cs的代码：

1 public class RuntimeHelper 2     { 3         ///  4         /// 获取项目程序集，排除所有的系统程序集(Microsoft.***、System.***等)、Nuget下载包 5         /// 
 6         /// 
        7         public static IList
       
         GetAllAssemblies() 8         { 9             var list = new List
        
         ();10             var deps = DependencyContext.Default;11             var libs = deps.CompileLibraries.Where(lib => !lib.Serviceable && lib.Type != "package");//排除所有的系统程序集、Nuget下载包12             foreach (var lib in libs)13             {14                 try15                 {16                     var assembly = AssemblyLoadContext.Default.LoadFromAssemblyName(new AssemblyName(lib.Name));17                     list.Add(assembly);18                 }19                 catch (Exception)20                 {21                     // ignored22                 }23             }24             return list;25         }26 27         public static Assembly GetAssembly(string assemblyName)28         {29             return GetAllAssemblies().FirstOrDefault(assembly => assembly.FullName.Contains(assemblyName));30         }31 32         public static IList
         
           GetAllTypes()33         {34             var list = new List
          
           ();35             foreach (var assembly in GetAllAssemblies())36             {37                 var typeInfos = assembly.DefinedTypes;38                 foreach (var typeInfo in typeInfos)39                 {40                     list.Add(typeInfo.AsType());41                 }42             }43             return list;44         }45 46         public static IList
           
             GetTypesByAssembly(string assemblyName)47         {48             var list = new List
            
             ();49 var assembly = AssemblyLoadContext.Default.LoadFromAssemblyName(new AssemblyName(assemblyName));50 var typeInfos = assembly.DefinedTypes;51 foreach (var typeInfo in typeInfos)52 {53 list.Add(typeInfo.AsType());54 }55 return list;56 }57 58 public static Type GetImplementType(string typeName, Type baseInterfaceType)59 {60 return GetAllTypes().FirstOrDefault(t =>61 {62 if (t.Name == typeName &&63 t.GetTypeInfo().GetInterfaces().Any(b => b.Name == baseInterfaceType.Name))64 {65 var typeInfo = t.GetTypeInfo();66 return typeInfo.IsClass && !typeInfo.IsAbstract && !typeInfo.IsGenericType;67 }68 return false;69 });70 }71 }

好了，到此就基本完成了，记得在Startup.cs加上：

1 // This method gets called by the runtime. Use this method to add services to the container. 2         public IServiceProvider ConfigureServices(IServiceCollection services) 3         { 4             services.RegisterAssembly("IServices"); 5             services.Configure
       
        ( 6                 options => options.AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(5));//设置缓存有效时间为5分钟。 7              8             // Add framework services. 9             services.AddMvc();10 11             return services.BuilderInterceptableServiceProvider(builder => builder.SetDynamicProxyFactory());12         }