什么是AspectCore Project ?

AspectCore Project 是適用于Asp.Net Core 平臺的輕量級 Aop(Aspect-oriented programming) 解決方案，它更好的遵循Asp.Net Core的模塊化開發理念，使用AspectCore可以更容易構建低耦合、易擴展的Web應用程序。AspectCore使用Emit實現高效的動態代理從而不依賴任何第三方Aop庫。

開使使用AspectCore

啟動 Visual Studio。從 File 菜單, 選擇 New > Project。選擇 ASP.NET Core Web Application 項目模版，創建新的 ASP.NET Core Web Application 項目。

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");    }   } }

定義ICustomService接口和它的實現類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();  }}

注冊ICustomService，接著，在ConfigureServices中配置創建代理類型的容器:

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

攔截器配置。首先安裝AspectCore.Extensions.Configuration package：

PM> Install-Package AspectCore.Extensions.Configuration

全局攔截器。使用AddAspectCore(Action<AspectCoreOptions>)的重載方法，其中AspectCoreOptions提供InterceptorFactories注冊全局攔截器:

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

帶構造器參數的全局攔截器，在CustomInterceptorAttribute中添加帶參數的構造器：

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");    }  }}