observerstructural.cs

来自「使用C#程序将23个常用设计模式进行列表显示」· CS 代码 · 共 95 行

using System;
using System.Windows.Forms;
using System.Collections;

namespace DesignPattern.ObserverStructural
{
    class ObserverStructural : AbstractPattern
    {
        public static void Run(TextBox tbInfo)
        {
            s_tbInfo = tbInfo;
            s_tbInfo.Text = "";

            // Configure Observer pattern 
            ConcreteSubject s = new ConcreteSubject(); 
            
            s.Attach(new ConcreteObserver(s,"X")); 
            s.Attach(new ConcreteObserver(s,"Y")); 
            s.Attach(new ConcreteObserver(s,"Z")); 
            
            // Change subject and notify observers 
            s.SubjectState = "ABC"; 
            s.Notify(); 
            
            // Wait for user 
            //Console.Read();
        }
    }
    // "Subject" 
    abstract class Subject 
    {
        private ArrayList observers = new ArrayList(); 
        public void Attach(Observer observer) 
        {
            observers.Add(observer); 
        }
        public void Detach(Observer observer) 
        {
            observers.Remove(observer); 
        }
        public void Notify() 
        {
            foreach (Observer o in observers) 
            {
                o.Update(); 
            }
        }
    }
    
    // "ConcreteSubject" 
    class ConcreteSubject : Subject 
    {
        private string subjectState; 
        
        // Property 
        public string SubjectState
        {
            get{ return subjectState; } 
            set{ subjectState = value; } 
        }
    }
    
    // "Observer" 
    abstract class Observer 
    {
        public abstract void Update();
    } 
    // "ConcreteObserver" 
    class ConcreteObserver : Observer 
    {
        private string name; 
        private string observerState;
        private ConcreteSubject subject; 
        
        // Constructor 
        public ConcreteObserver( ConcreteSubject subject, string name) 
        {
            this.subject = subject; 
            this.name = name; 
        }
        public override void Update() 
        {
            observerState = subject.SubjectState;
            DesignPattern.FormMain.OutputInfo("Observer {0}'s new state is {1}", name, observerState); 
        }
        
        // Property 
        public ConcreteSubject Subject 
        {
            get { return subject; } 
            set { subject = value; } 
        }
    }
}