访问者模式

刺骨的言语ヽ痛彻心扉 2021-09-17 00:08 407阅读 0赞

## 21.访问者模式 ##

![70][]

public abstract class Element
        {
            public abstract void Accept(IVistor vistor);
            public abstract void Print();
        }
    
        public class ElementA : Element
        {
            public override void Accept(IVistor vistor)
            {
                vistor.Visit(this);
            }
            public override void Print()
            {
                Console.WriteLine("我是元素A");
            }
        }
        public class ElementB : Element
        {
            public override void Accept(IVistor vistor)
            {
                vistor.Visit(this);
            }
            public override void Print()
            {
                Console.WriteLine("我是元素B");
            }
        }
        public interface IVistor// 抽象访问者
        {
            void Visit(ElementA a);
            void Visit(ElementB b);
        }
        public class ConcreteVistor : IVistor// 具体访问者
        {
            public void Visit(ElementA a)
            {
                a.Print();
            }
            public void Visit(ElementB b)
            {
                b.Print();
            }
        }
        public class ObjectStructure// 对象结构
        {
            private ArrayList elements = new ArrayList();
            public ArrayList Elements
            {
                get { return elements; }
            }
            public ObjectStructure()
            {
                Random ran = new Random();
                for (int i = 0; i < 6; i++)
                {
                    int ranNum = ran.Next(10);
                    if (ranNum > 5)
                    {
                        elements.Add(new ElementA());
                    }
                    else
                    {
                        elements.Add(new ElementB());
                    }
                }
            }
        }
        class Program
        {
            static void Main(string[] args)
            {
                ObjectStructure objectStructure = new ObjectStructure();
                foreach (Element e in objectStructure.Elements)
                {
                    e.Accept(new ConcreteVistor());// 每个元素接受访问者访问
                }
                Console.Read();
            }
        }

![70 1][]

[70]: /images/20210725/af7e78c0d6c24be1a1607c913ab2a742.png
[70 1]: /images/20210725/26eeab57500a4f28910a43b4472c617f.png