C#设计模式系列 1 ----Observer 观察者模式之牛顿童鞋的成绩

OStack程序员社区-中国程序员成长平台 › 门户 › 编程› Node.js›Node.js教程

原作者: [db:作者] 来自: [db:来源] 收藏邀请

1.理论定义

观察者模式描述了一种一对多的关系。当某一对象的状态发生改变时，其他对象会得到改变的通知。并作出相应的反应。

2.应用举例

需求描述：牛顿同学的期末考试成绩(Score)出来了，各科老师都想知道自己的学生成绩情况！

语文老师(TeacherChinese)只关心牛顿的语文(Chinese)成绩.

英语老师(TeacherEnglish)只关心牛顿的英语(English)成绩.

数学老师(TeacherMathematics)只关心牛顿的数学(Mathematics)成绩.

班主任想关心(TeacherTeacherHead) 牛顿的各科成绩和总成绩(TotalScore).

成绩出来后，各科老师都得到通知(Notify).

3.具体编码

1.添加学生信息类，里面只有一个Name属性。

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

namespace Com.Design.Gof.Observer
{
    /// <summary>
    /// 学生信息类
    /// </summary>
    public class Student
    {
        /// <summary>
        /// 姓名
        /// </summary>
        public string Name { get; set; }
    }
}

2.成绩单(Score)

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

namespace Com.Design.Gof.Observer
{
    public delegate void NotifyEventHandler(Score score); 
    public class Score
    {
        public Score() { }
        //事件声明
        public NotifyEventHandler NotifyEvent=null;
        /// <summary>
        /// 调用入口
        /// </summary>
        public void Notify() {
            OnNotifyChange();
        }
      /// <summary>
      ///通知事件
      /// </summary>
        private void OnNotifyChange() {
            if (NotifyEvent != null) {
                NotifyEvent(this);
            }
        }
        /// <summary>
        /// 数学成绩
        /// </summary>
        public float Mathematics { get; set; }
        /// <summary>
        /// 英语成绩
        /// </summary>
        public float English { get; set; }
        /// <summary>
        /// 语文成绩
        /// </summary>
        public float Chinese { get; set; }
        /// <summary>
        /// 三科总成绩
        /// </summary>
        public float TotalScore {
            get { 
               return Mathematics+English+Chinese;
           }
        }
        /// <summary>
        /// 学生基本信息
        /// </summary>
        public Student student { get; set; }

    }
}

3.语文老师

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

namespace Com.Design.Gof.Observer
{
    /// <summary>
    /// 语文老师
    /// </summary>
    public class TeacherChinese
    {
        public void Receive(Score score) {
            Console.WriteLine("我是语文老师，我只关心"+score.student.Name+"的语文成绩:"+score.Chinese+"分");
        }
    }
}

4.英语老师

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

namespace Com.Design.Gof.Observer
{
    /// <summary>
    /// 英语老师
    /// </summary>
    public class TeacherEnglish
    {
        public void Receive(Score score) {
            Console.WriteLine("我是英语老师，我只关心" + score.student.Name + "的英语成绩:" + score.English + "分");
        }
    }
}

5.数学老师

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

namespace Com.Design.Gof.Observer
{
    /// <summary>
    /// 数学老师
    /// </summary>
    public class TeacherMathematics
    {
        public void Receive(Score score) {
            Console.WriteLine("我是数学老师，我只关心" + score.student.Name + "的数学成绩:" + score.Mathematics + "分");
        }
    }
}

6.班主任

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

namespace Com.Design.Gof.Observer
{
    /// <summary>
    /// 班主任
    /// </summary>
    public class TeacherTeacherHead
    {
        public void Receive(Score score) {
            string name=score.student.Name;
            Console.WriteLine("我是班主任，我要关心 " + name + " 的各科成绩和总成绩");
          
            Console.WriteLine(name + "的 语文 成绩: " + score.Chinese + " 分");
            Console.WriteLine(name + "的 英语 成绩: " + score.English + " 分");
            Console.WriteLine(name + "的 数学 成绩: " + score.Mathematics + " 分");
            Console.WriteLine(name + "的 总 成绩: " + score.TotalScore + " 分");
        }
    }
}

7.下面是主函数调用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Com.Design.Gof.Observer;
namespace Com.Design.Gof.Test
{
    class Program
    {
        static void Main(string[] args)
        {
            #region Observer
            /*牛顿同学的成绩单*/
            Score score = new Score {
                Chinese = 60,
                Mathematics = 100,
                English = 90,
                student = new Student { Name = "牛顿" }
            };

            TeacherChinese teacherChinese = new TeacherChinese();   //语文老师
            TeacherEnglish teacherEnglish = new TeacherEnglish();//英语老师
            TeacherMathematics teacherMathematics = new TeacherMathematics();//数学老师
            TeacherTeacherHead teacherTeacherHead = new TeacherTeacherHead();//班主任
            //牛顿成绩单出来了，老师都想知道这个结果。
            score.NotifyEvent += new NotifyEventHandler(teacherChinese.Receive);
            score.NotifyEvent += new NotifyEventHandler(teacherEnglish.Receive);
            score.NotifyEvent += new NotifyEventHandler(teacherMathematics.Receive);
            score.NotifyEvent += new NotifyEventHandler(teacherTeacherHead.Receive);

            //向 各 学科  老师发送 有针对性的，感兴趣的  成绩
            score.Notify();
            #endregion
            Console.ReadKey();
        }
    }
}