Asp.Net Core轻量级Aop解决方案：AspectCore

什么是AspectCore Project ?

AspectCore Project 是适用于Asp.Net Core 平台的轻量级 Aop(Aspect-oriented programming) 解决方案，它更好的遵循Asp.Net Core的模块化开发理念，使用AspectCore可以更容易构建低耦合、易扩展的Web应用程序。AspectCore使用Emit实现高效的动态代理从而不依赖任何第三方Aop库。

开使使用AspectCore

启动 Visual Studio。从 File 菜单, 选择 New > Project。选择 ASP.NET Core Web Application 项目模版，创建新的 ASP.NET Core Web Application 项目。

public class CustomInterceptorAttribute : InterceptorAttribute{  public async override Task Invoke(IAspectContext context, AspectDelegate next)  {    try    {      Console.WriteLine("Before service call");      await next(context);    }    catch (Exception)    {      Console.WriteLine("Service threw an exception!");      throw;    }    finally    {      Console.WriteLine("After service call");    }   } }

定义ICustomService接口和它的实现类CustomService:

public interface ICustomService{  [CustomInterceptor]  void Call();}public class CustomService : ICustomService{  public void Call()  {    Console.WriteLine("service calling...");  }}

在HomeController中注入ICustomService:

public class HomeController : Controller{  private readonly ICustomService _service;  public HomeController(ICustomService service)  {    _service = service;  }  public IActionResult Index()  {    _service.Call();    return View();  }}

注册ICustomService，接着，在ConfigureServices中配置创建代理类型的容器:

public IServiceProvider ConfigureServices(IServiceCollection services){  services.AddTransient<ICustomService, CustomService>();  services.AddMvc();  services.AddAspectCore();  return services.BuildAspectCoreServiceProvider();}

拦截器配置。首先安装AspectCore.Extensions.Configuration package：

PM> Install-Package AspectCore.Extensions.Configuration

全局拦截器。使用AddAspectCore(Action<AspectCoreOptions>)的重载方法，其中AspectCoreOptions提供InterceptorFactories注册全局拦截器:

 services.AddAspectCore(config => {   config.InterceptorFactories.AddTyped<CustomInterceptorAttribute>(); });

带构造器参数的全局拦截器，在CustomInterceptorAttribute中添加带参数的构造器：

public class CustomInterceptorAttribute : InterceptorAttribute{  private readonly string _name;  public CustomInterceptorAttribute(string name)  {    _name = name;  }  public async override Task Invoke(AspectContext context, AspectDelegate next)  {    try    {      Console.WriteLine("Before service call");      await next(context);    }    catch (Exception)    {      Console.WriteLine("Service threw an exception!");      throw;    }    finally    {      Console.WriteLine("After service call");    }  }}