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。
从 Nuget 安装 AspectCore.Extensions.DependencyInjection package: PM> Install-Package AspectCore.Extensions.DependencyInjection 在一般情况下可以使用抽象的InterceptorAttribute自定义特性类，它实现IInterceptor接口。AspectCore默认实现了基于Attribute的拦截器配置。我们的自定义拦截器看起来像下面这样:
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");
}
}
}
