观察者模式

Author: XINCGer

DesignPatterns/ObserverPattern/ObserverPattern/Observer.cs

@@ -39,7 +39,8 @@ public ConcreteObserver(Subject subject, string observerName)
 
         public override void Update()
         {
-            throw new NotImplementedException();
+            State = subject.GetState();
+            Console.WriteLine(observerName+"观察到的状态:"+State);
         }
     }
 }

DesignPatterns/ObserverPattern/ObserverPattern/Program.cs

@@ -21,6 +21,13 @@ static void Main(string[] args)
             spy.SetIntelligence("研制武器！");
 
             spy.Notify();
+
+            Subject subject = new ConcreteSubject();
+            subject.Attach(new ConcreteObserver(subject,"1号观察者"));
+            subject.Attach(new ConcreteObserver(subject,"2号观察者"));
+            subject.Attach(new ConcreteObserver(subject,"3号观察者"));
+            subject.SetState("Talking");
+            subject.Notify();
         }
     }
 }

DesignPatterns/ObserverPattern/ObserverPattern/Subject.cs

@@ -1,13 +1,55 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Security.Cryptography.X509Certificates;
 using System.Text;
 using System.Threading.Tasks;
 
 namespace ObserverPattern
 {
     abstract class Subject
     {
-        private List<Observer> 
+        protected string state;
+
+        private List<Observer> listeners =new List<Observer>();
+
+        /// <summary>
+        /// 注册
+        /// </summary>
+        /// <param name="observer"></param>
+        public void Attach(Observer observer)
+        {
+            listeners.Add(observer);
+        }
+
+        //反注册
+        public void Detch(Observer observer)
+        {
+            listeners.Remove(observer);
+        }
+
+        public void Notify()
+        {
+            foreach (var listener in listeners)
+            {
+                listener.Update();
+            }
+        }
+
+        public abstract void SetState(string state);
+        public abstract string GetState();
+    }
+
+    class ConcreteSubject : Subject
+    {
+        public override void SetState(string state)
+        {
+            this.state = state;
+        }
+
+        public override string GetState()
+        {
+            return this.state;
+        }
     }
 }