C# 委托+事件实现发布与订阅

 

using System;

namespace Observer
{
    /// <summary>
    /// 声明一个委托类型
    /// </summary>
    /// <param name="ringKind">表示铃声种类(1 表示上课铃声；2 表示下课铃声)</param>
    public delegate void RingEvent(int ringKind);


    class Program
    {
        static void Main(string[] args)
        {
            //使用学校打铃实现发布订阅
            SchoolRing sr = new SchoolRing();//发布者
            Students stu1 = new Students("张三");//订阅者1
            Students stu2 = new Students("李四");//订阅者2
            //张三订阅铃声委托
            stu1.SubscribeToRing(sr);
            stu2.SubscribeToRing(sr);
            Console.WriteLine("请输入大铃声参数(1:表示上课铃；2:表示下课铃)：");
            //发布打铃动作
            sr.Jow(Convert.ToInt32(Console.ReadLine()));


            Console.ReadLine();
        }
    }


    public class SchoolRing:Students
    {
        public event RingEvent OnbellSound;//委托事件，作为发布者
        public void Jow(int ringKind)
        {
            //if (ringKind == 1 || ringKind == 2)
            //{
            //    Console.Write(ringKind == 1 ? "上课铃响了！" : "下课铃响了！");
            //}
            if (OnbellSound != null)
            {//说明她已订阅了具体的方法
                OnbellSound(ringKind);//回调onbellSound委托订阅的具体方法
            }
            else
            {
                Console.WriteLine("铃声参数不对，1是上课铃，2是下课铃");
            }
        }
    }

    public class Students
    {
        public string Name { get; set; }
        public Students()
        {
        }
        public Students(string name) {
            this.Name = name;
        }
        //订阅事件
        private void SchoolJow(int ringKind)
        {
            if (ringKind == 2)
            {
                Console.WriteLine("下课铃响了，"+this.Name+"可以休息了！");
            }
            else if (ringKind == 1)
            {
                Console.WriteLine("上课铃响了，" + this.Name + "认真学习！");
            }
        }

        //学生订阅铃声委托事件
        public void SubscribeToRing(SchoolRing school)
        {
            school.OnbellSound += SchoolJow;
        }

        public void CancelSubscribe(SchoolRing school) {
            school.OnbellSound -= SchoolJow;
        }
    }


}