设计模式之职责链模式

class Client {
        
    static void Main(string[] args) {
        Handler handlerChain = new ConcreteHandler1(new ConcreteHandler2(null));

        Request request1 = new ConcreteRequest1();
        handlerChain.HandleRequest(request1);

        Request request2 = new ConcreteRequest2();
        handlerChain.HandleRequest(request2);

        Console.ReadKey();
    }
}

public abstract class Handler {

    private readonly Handler _successor;

    protected Handler(Handler successor) {
        this._successor = successor;
    }

    protected Handler Successor {
        get {
            return this._successor;
        }
    }

    public abstract void HandleRequest(Request request);

}

public class ConcreteHandler1 : Handler {
        
    public ConcreteHandler1(Handler successor) : base(successor) {
    }

    public override void HandleRequest(Request request) {
        if (request is ConcreteRequest1) {
            Console.WriteLine("ConcreteRequest1 is handled by ConcreteHandler1");
        }
        else {
            this.Successor.HandleRequest(request);
        }
    }
}

public class ConcreteHandler2 : Handler {

    public ConcreteHandler2(Handler successor) : base(successor) {
    }

    public override void HandleRequest(Request request) {
        if (request is ConcreteRequest2) {
            Console.WriteLine("ConcreteRequest2 is handled by ConcreteHandler2");
        }
        else {
            this.Successor.HandleRequest(request);
        }
    }
}

public abstract class Request {
}

public class ConcreteRequest1 : Request {
}

public class ConcreteRequest2 : Request {

}