C#设计模式之Observer观察者模式解决牛顿童鞋成绩问题示例

2020-01-24 00:28:59

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本文实例讲述了C#设计模式之Observer观察者模式解决牛顿童鞋成绩问题。分享给大家供大家参考，具体如下：

一.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。

二.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).

三.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();  } }}

8.运行结果