接口的城堡动态代理和未派生 Class

Question

namespace DynamicInterception
{
    public class Calculator
    {
        public virtual int Div(int a, int b)
        {
            try
            {
                return a / b;
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message.ToString());
                return 0;
            }
        }
    }

    [Serializable]
    public abstract class Interceptor : IInterceptor
    {
        public void Intercept(IInvocation invocation)
        {
            ExecuteBefore(invocation);
            invocation.Proceed();
            ExecuteAfter(invocation);
        }
        protected abstract void ExecuteAfter(IInvocation invocation);
        protected abstract void ExecuteBefore(IInvocation invocation);
    }

    public class CalculatorInterceptor : Interceptor
    {
        protected override void ExecuteBefore(Castle.DynamicProxy.IInvocation invocation)
        {
            Console.WriteLine("Start: {0}", invocation.Method.Name);
        }

        protected override void ExecuteAfter(Castle.DynamicProxy.IInvocation invocation)
        {
            Console.WriteLine("End: {0}", invocation.Method.Name);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            ProxyGenerator generator = new ProxyGenerator();
            Calculator c = generator.CreateClassProxy<Calculator>(new CalculatorInterceptor());
            var r = c.Div(11, 0);
            Console.ReadKey();
        }
    }
}

是否可以替换public virtual int Div(int a,int b) 带接口

interface ICalculator
{
    int Div(int a, int b);
}

代理声明应该怎样？

ProxyGenerator generator = new ProxyGenerator();
Calculator c = generator.CreateClassProxy<Calculator>(new CalculatorInterceptor());

Answer 1

如果你想添加一个接口到 Calculator 并执行这两行它的工作原理是一样的：

public interface ICalculator
{
    int Div(int a, int b);
}

public class Calculator : ICalculator
{

    public int Div(int a, int b)
    {
        try
        {
            return a / b;
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message.ToString());
            return 0;
        }
    }
}

ProxyGenerator generator = new ProxyGenerator();
Calculator c = generator.CreateClassProxy<Calculator>(new CalculatorInterceptor());

但是您实际上并没有为此做任何事情 - 您仍在为具体的派生类型创建代理。我假设您想要 "CreateClassProxy<ICalculator>" 之类的东西。这行不通，因为 CreateClassProxy 对 where TClass : class.

有通用约束

您拥有的是多种CreateInterfaceProxt.. 方法，您可以尝试。但是像下面这样的天真执行仍然行不通：

ICalculator c = generator.CreateInterfaceProxyWithoutTarget<ICalculator>(new CalculatorInterceptor());
c.Div(1, 2);

它将执行，调用拦截器并在运行时失败 invocation.Proceed(); 并出现错误：

System.NotImplementedException This is a DynamicProxy2 error: The interceptor attempted to 'Proceed' for method 'Int32 Div(Int32, Int32)' which has no target. When calling method without target there is no implementation to 'proceed' to and it is the responsibility of the interceptor to mimic the implementation (set return value, out arguments etc)

因此，正如 Castle 的良好指示性（严重）错误所指定的那样 - 您必须以某种方式为其实现 - 或者通过在拦截器中自己指示 - 通过为该接口注册 Component 。

相反，您可以这样做：（检查代码中的注释）

ProxyGenerator generator = new ProxyGenerator();

ICalculator calculator = new Calculator();
var proxyCalculator = generator.CreateInterfaceProxyWithTarget(typeof(ICalculator),calculator, new CalculatorInterceptor());

calculator.Div(1, 2); // Will execute but will not be intercepted
((ICalculator)proxyCalculator).Div(11, 0); //Will execute and will be intercepted

但是说完我上面所说的，如果所有这一切背后的目的是让拦截器拦截您的方法，那么只需 "good-old" 注册到容器：

WindsorContainer container = new WindsorContainer();
container.Register(
    Component.For<CalculatorInterceptor>(),
    Component.For<ICalculator>()
             .ImplementedBy<Calculator>()
             .Interceptors<CalculatorInterceptor>());

var calculator = container.Resolve<ICalculator>();
calculator.Div(1, 0);

// Output:
// Start: Div
// Attempted to divide by zero
// End: Div

接口的城堡动态代理和未派生 Class

Castle Dynamic Proxy of Interface and not Derived Class

c#

proxy

castle-windsor

castle-dynamicproxy