public interface IA{    void DoSth();}public class A: IA{    public virtual void DoSth() { }}public class B : A,IA{    public override void DoSth()    {        before();        base.DoSth();        after();    }    public void before() { }    public void after() { }}　

public interface IA{    void DoSth();}public class A2: IA{    public void DoSth() { }}public class B2 : IA{    private IA a;    public B2(IA a)    {        this.a = a;    }    public void DoSth()    {        before();        this.a.DoSth();        after();    }    public void before() { }    public void after() { }}

public interface IA{    void DoSth();}public class A3 : IA{    public void DoSth() { }    public void Proceed()    {        DoSth();    }}public class MyInterceptor{    public void Intercept(IA invocation)    {        before();        if(invocation != null)            invocation.DoSth();        after();    }    public void before() { }    public void after() { }}

public interface IAdditionalOp{    void before();    void after();}public class AdditionalOp :Attribute, IAdditionalOp{    public void before() { }    public void after() { }}public class A4{    [AdditionalOp]    public void DoSth() { }}public class B4{    public void Run()    {        var classUnder = typeof(A4);        var allMethods = classUnder.GetMethods();        var methodUnder = allMethods.Where(m => m.Name == "DoSth");                foreach (MethodInfo methodInfo in methodUnder)        {            Attribute[] attributes = Attribute.GetCustomAttributes(methodInfo, typeof(AdditionalOp));            foreach (var item in attributes)            {                (item as AdditionalOp).before();            }            A4 a4 = new A4();            a4.DoSth();            foreach (var item in attributes)            {                (item as AdditionalOp).after();            }        }    }}