C#事件发布与订阅

书店新书通知 ，根据顾客的兴趣领域

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace _2
{
    enum Domain{Computer,Economics,Literature,Sport};
    delegate void BookHandler(BookStore sender,Domain dom,string book);
    class BookStore
    {
        public string _name;
        public event BookHandler OnNewBook;

        public string Name
        {
            get { return _name; }
        }

        public BookStore(string name)
        {
            _name = name;
        }
        public void NewBook(Domain dom, string book)
        {
            OnNewBook(this, dom, book);
        }
    }

    class Customer
    {
        private string _name;
        private Domain _dom;

        public Customer(string name, Domain dom)
        {
            _name = name;
            _dom = dom;
        }

        void store_OnNewBook(BookStore store, Domain dom, string book)
        {
            if (dom == _dom)
                Console.WriteLine("{0}您好：{1}店新到新书《{2}》", _name, store.Name, book);
        }
        public void Register(BookStore store)
        {
            store.OnNewBook += store_OnNewBook;
        }
        public void UnRegister(BookStore store)
        {
            store.OnNewBook -= store_OnNewBook;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            BookStore store1 = new BookStore("中关村");
            BookStore store2 = new BookStore("中山路");
            Customer[] cs = new Customer[]{
                new Customer("王小明",Domain.Computer),
                new Customer("赵丽",Domain.Computer),
                new Customer("张珊",Domain.Literature)
            };
            foreach (Customer c in cs)
            {
                c.Register(store1);
                c.Register(store2);
            }
            store1.NewBook(Domain.Computer, "C#程序设计");
            store2.NewBook(Domain.Literature, "唐诗三百首");
            cs[0].UnRegister(store2);
            store2.NewBook(Domain.Computer, "数据结构");
        }
    }
}