觀察者模式（Observer Pattern）

觀察者模式（Observer Pattern）是一種對象行為模式。它定義對象間的一種一對多的依賴關系，當一個對象的狀態(tài)發(fā)生改變時，所有依賴于它的對象都得到通知并被自動更新。在觀察者模式中，主體是通知的發(fā)布者，它發(fā)出通知時并不需要知道誰是它的觀察者，可以有任意數(shù)目的觀察者訂閱并接收通知。觀察者模式不僅被廣泛應用于軟件界面元素之間的交互，在業(yè)務對象之間的交互、權限管理等方面也有廣泛的應用。觀察者模式的主要的作用就是對對象解耦，將觀察者和被觀察者完全隔離。

1）面向對象方式實現(xiàn)

using System;
using System.Collections.Generic;
namespace ConsoleApplication
{
    //一般每個接口或類都寫在單獨的.cs文件中
    //本示例為了執(zhí)行查看方便才寫在一起  
    /// 
    public interface IObserver
    {
        void Action();
    }
    public class Baby : IObserver
    {
        public void Action()
        {
            this.Cry();
        }
        public void Cry()
        {
            Console.WriteLine("{0} Cry", this.GetType().Name);
        }
    }
    public class Brother : IObserver
    {
        public void Action()
        {
            this.Turn();
        }
        public void Turn()
        {
            Console.WriteLine("{0} Turn", this.GetType().Name);
        }
    }
    public class Chicken : IObserver
    {
        public void Action()
        {
            this.Woo();
        }
        public void Woo()
        {
            Console.WriteLine("{0} Woo", this.GetType().Name);
        }
    }
    public class Dog : IObserver
    {
        public void Action()
        {
            this.Wang();
        }
        public void Wang()
        {
            Console.WriteLine("{0} Wang", this.GetType().Name);
        }
    }
    public class Neighbor : IObserver
    {
        public void Action()
        {
            this.Awake();
        }
        public void Awake()
        {
            Console.WriteLine("{0} Awake", this.GetType().Name);
        }
    }
    public class Animal
    {
        //一般的實現(xiàn)
        //public void Sound()
        //{
        //    Console.WriteLine("{0} Sound.....", this.GetType().Name);
        //    new Chicken().Woo();
        //    new Baby().Cry();
        //    new Brother().Turn();
        //    new Dog().Wang();
        //    new Neighbor().Awake();
        //}
        private List<IObserver> _ObserverList = new List<IObserver>();
        public void Add(IObserver observer)
        {
            this._ObserverList.Add(observer);
        }
        public void Remove(IObserver observer)
        {
            this._ObserverList.Remove(observer);
        }
        public void SoundObserver()
        {
            Console.WriteLine("{0} SoundObserver.....", this.GetType().Name);
            foreach (var observer in this._ObserverList)
            {
                observer.Action();
            }
        }
    }
    // 
    /// 觀察者模式
    /// 對象和行為的分離
    /// 
    class Program
    {
        static void Main(string[] args)
        {
            Animal animal = new Animal();
            animal.Add(new Baby());
            animal.Add(new Brother());
            animal.Add(new Chicken());
            animal.Add(new Dog());
            animal.Add(new Neighbor());
            animal.SoundObserver();
        }
    }
}

?2）事件委托方式實現(xiàn)

using System;
using System.Collections.Generic;
namespace ConsoleApplianimalion
{
    //一般每個接口或類都寫在單獨的.cs文件中
    //本示例為了執(zhí)行查看方便才寫在一起  
    public interface IObserver
    {
        void Action();
    }
    public class Baby : IObserver
    {
        public void Action()
        {
            this.Cry();
        }
        public void Cry()
        {
            Console.WriteLine("{0} Cry", this.GetType().Name);
        }
    }
    public class Brother : IObserver
    {
        public void Action()
        {
            this.Turn();
        }
        public void Turn()
        {
            Console.WriteLine("{0} Turn", this.GetType().Name);
        }
    }
    public class Chicken : IObserver
    {
        public void Action()
        {
            this.Woo();
        }
        public void Woo()
        {
            Console.WriteLine("{0} Woo", this.GetType().Name);
        }
    }
    public class Dog : IObserver
    {
        public void Action()
        {
            this.Wang();
        }
        public void Wang()
        {
            Console.WriteLine("{0} Wang", this.GetType().Name);
        }
    }
    public class Neighbor : IObserver
    {
        public void Action()
        {
            this.Awake();
        }
        public void Awake()
        {
            Console.WriteLine("{0} Awake", this.GetType().Name);
        }
    }
    public class Animal
    {
        //一般的實現(xiàn)
        //public void Sound()
        //{
        //    Console.WriteLine("{0} Sound.....", this.GetType().Name);
        //    new Chicken().Woo();
        //    new Baby().Cry();
        //    new Brother().Turn();
        //    new Dog().Wang();
        //    new Neighbor().Awake();
        //}
        public event Action SoundHandler;
        public void SoundEvent()
        {
            Console.WriteLine("{0} SoundEvent.....", this.GetType().Name);
            if (this.SoundHandler != null)
            {
                //foreach (Action action in this.SoundHandler.GetInvoanimalionList())
                //{
                //    action.Invoke();
                //}
                this.SoundHandler.Invoke();
            }
        }
    }
    // 
    /// 觀察者模式
    /// 對象和行為的分離
    /// 
    class Program
    {
        static void Main(string[] args)
        {
            Animal animal = new Animal();
            animal.SoundHandler += new Action(() => new Dog().Wang());
            animal.SoundHandler += new Chicken().Woo;
            animal.SoundHandler += new Baby().Cry;
            animal.SoundHandler += new Brother().Turn;
            animal.SoundHandler += new Neighbor().Awake;
            animal.SoundEvent();
        }
    }
}

?文章來源地址http://www.zghlxwxcb.cn/news/detail-562361.html

到了這里，關于C#設計模式之---觀察者模式的文章就介紹完了。如果您還想了解更多內容，請在右上角搜索TOY模板網(wǎng)以前的文章或繼續(xù)瀏覽下面的相關文章，希望大家以后多多支持TOY模板網(wǎng)！