C# 面向切面编程之AspectCore初探

写在前面

?AspectCore 是Lemon名下的一个国产Aop框架，提供了一个全新的轻量级和模块化的Aop解决方案。面向切面也可以叫做代码拦截，分为静态和动态两种模式，AspectCore 可以实现动态代理，支持程序运行时在内存中“临时”生成 AOP 动态代理类。

老规矩从 Nuget 安装 AspectCore.Extensions.DependencyInjection 包。

代码实现

using AspectCore.DynamicProxy;

public class Program
{
    public static void Main(string[] args)
    {
        Console.WriteLine("Start...");
        ProxyGeneratorBuilder proxyGeneratorBuilder = new ProxyGeneratorBuilder();
        using (IProxyGenerator proxyGenerator = proxyGeneratorBuilder.Build())
        {
            Person p = proxyGenerator.CreateClassProxy<Person>();
            Console.WriteLine(p.GetType().BaseType);
            p.Say($"{Environment.NewLine} Hello World!");
        }
        Console.WriteLine("End");
        Console.ReadLine();
    }
}

public class CustomInterceptor : AbstractInterceptorAttribute
{
    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");
        }
    }
}

public class Person
{
    [CustomInterceptor]
    public virtual void Say(string msg)
    {
        Console.WriteLine("service calling..." + msg);
    }
}

调用示例

如图，代理类将Say方法包裹了起来。

如果修改一下CustomInterceptor 的Invoke方法，可以直接根据条件控制代码的分支跳转。

public class CustomInterceptor : AbstractInterceptorAttribute
{
    public async override Task Invoke(AspectContext context, AspectDelegate next)
    {
        try
        {
            Console.WriteLine("Before service call");
            if (false)
                await next(context);
            else
                await Task.Delay(1000);
        }
        catch (Exception)
        {
            Console.WriteLine("Service threw an exception!");
            throw;
        }
        finally
        {
            Console.WriteLine("After service call");
        }
    }
}

?运行代码 Person中的Say方法本体就被跳过了：

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