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：
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
//services.RegisterAssembly("IServices");
services.AddSingleton<IUserService, UserService>();
// Add framework services.
services.AddMvc();
services.AddMvcCore()
.AddApiExplorer();
services.AddSwaggerGen(options =>
{
options.SwaggerDoc("v1", new Info()
{
Title = "Swagger测试",
Version = "v1",
Description = "Swagger测试RESTful API ",
TermsOfService = "None",
Contact = new Contact
{
Name = "来来吹牛逼",
Email = "xxoo123@outlook.com"
},
});
//设置xml注释文档，注意名称一定要与项目名称相同
var filePath = Path.Combine(PlatformServices.Default.Application.ApplicationBasePath, "WebApi.xml");
options.IncludeXmlComments(filePath);
});
}
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：
/// <summary>
/// IServiceCollection扩展
/// </summary>
public static class ServiceExtension
{
/// <summary>
/// 用DI批量注入接口程序集中对应的实现类。
/// <para>
/// 需要注意的是，这里有如下约定：
/// IUserService --> UserService, IUserRepository --> UserRepository.
/// </para>
/// </summary>
/// <param name="service"></param>
/// <param name="interfaceAssemblyName">接口程序集的名称（不包含文件扩展名）</param>
/// <returns></returns>
public static IServiceCollection RegisterAssembly(this IServiceCollection service, string interfaceAssemblyName)
{
if (service == null)
throw new ArgumentNullException(nameof(service));
if (string.IsNullOrEmpty(interfaceAssemblyName))
throw new ArgumentNullException(nameof(interfaceAssemblyName)); var assembly = RuntimeHelper.GetAssembly(interfaceAssemblyName);
if (assembly == null)
{
throw new DllNotFoundException($"the dll \"{interfaceAssemblyName}\" not be found");
} //过滤掉非接口及泛型接口
var types = assembly.GetTypes().Where(t => t.GetTypeInfo().IsInterface && !t.GetTypeInfo().IsGenericType); foreach (var type in types)
{
var implementTypeName = type.Name.Substring();
var implementType = RuntimeHelper.GetImplementType(implementTypeName, type);
if (implementType != null)
service.AddSingleton(type, implementType);
}
return service;
} /// <summary>
/// 用DI批量注入接口程序集中对应的实现类。
/// </summary>
/// <param name="service"></param>
/// <param name="interfaceAssemblyName">接口程序集的名称（不包含文件扩展名）</param>
/// <param name="implementAssemblyName">实现程序集的名称（不包含文件扩展名）</param>
/// <returns></returns>
public static IServiceCollection RegisterAssembly(this IServiceCollection service, string interfaceAssemblyName, string implementAssemblyName)
{
if (service == null)
throw new ArgumentNullException(nameof(service));
if(string.IsNullOrEmpty(interfaceAssemblyName))
throw new ArgumentNullException(nameof(interfaceAssemblyName));
if (string.IsNullOrEmpty(implementAssemblyName))
throw new ArgumentNullException(nameof(implementAssemblyName)); var interfaceAssembly = RuntimeHelper.GetAssembly(interfaceAssemblyName);
if (interfaceAssembly == null)
{
throw new DllNotFoundException($"the dll \"{interfaceAssemblyName}\" not be found");
} var implementAssembly = RuntimeHelper.GetAssembly(implementAssemblyName);
if (implementAssembly == null)
{
throw new DllNotFoundException($"the dll \"{implementAssemblyName}\" not be found");
} //过滤掉非接口及泛型接口
var types = interfaceAssembly.GetTypes().Where(t => t.GetTypeInfo().IsInterface && !t.GetTypeInfo().IsGenericType); foreach (var type in types)
{
//过滤掉抽象类、泛型类以及非class
var implementType = implementAssembly.DefinedTypes
.FirstOrDefault(t => t.IsClass && !t.IsAbstract && !t.IsGenericType &&
t.GetInterfaces().Any(b => b.Name == type.Name));
if (implementType != null)
{
service.AddSingleton(type, implementType.AsType());
}
} return service;
}
}
附上RuntimeHelper.cs的代码：
public class RuntimeHelper
{
/// <summary>
/// 获取项目程序集，排除所有的系统程序集(Microsoft.***、System.***等)、Nuget下载包
/// </summary>
/// <returns></returns>
public static IList<Assembly> GetAllAssemblies()
{
var list = new List<Assembly>();
var deps = DependencyContext.Default;
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
foreach (var lib in libs)
{
try
{
var assembly = AssemblyLoadContext.Default.LoadFromAssemblyName(new AssemblyName(lib.Name));
list.Add(assembly);
}
catch (Exception)
{
// ignored
}
}
return list;
} public static Assembly GetAssembly(string assemblyName)
{
return GetAllAssemblies().FirstOrDefault(assembly => assembly.FullName.Contains(assemblyName));
} public static IList<Type> GetAllTypes()
{
var list = new List<Type>();
foreach (var assembly in GetAllAssemblies())
{
var typeInfos = assembly.DefinedTypes;
foreach (var typeInfo in typeInfos)
{
list.Add(typeInfo.AsType());
}
}
return list;
} public static IList<Type> GetTypesByAssembly(string assemblyName)
{
var list = new List<Type>();
var assembly = AssemblyLoadContext.Default.LoadFromAssemblyName(new AssemblyName(assemblyName));
var typeInfos = assembly.DefinedTypes;
foreach (var typeInfo in typeInfos)
{
list.Add(typeInfo.AsType());
}
return list;
} public static Type GetImplementType(string typeName, Type baseInterfaceType)
{
return GetAllTypes().FirstOrDefault(t =>
{
if (t.Name == typeName &&
t.GetTypeInfo().GetInterfaces().Any(b => b.Name == baseInterfaceType.Name))
{
var typeInfo = t.GetTypeInfo();
return typeInfo.IsClass && !typeInfo.IsAbstract && !typeInfo.IsGenericType;
}
return false;
});
}
}
好了，到此就基本完成了，记得在Startup.cs加上：
// This method gets called by the runtime. Use this method to add services to the container.
public IServiceProvider ConfigureServices(IServiceCollection services)
{
services.RegisterAssembly("IServices"); // Add framework services.
services.AddMvc();
}
总结
小记一下，好记性不如烂笔头。