5 Decorator模式
5.1 概述
Decorator模式,又叫装饰模式,就是给一个对象额外地添加一些职责,以适应更多的变化。
5.2 设计
给一个对象添加职责,可以直接修改这个对象,但是这样就变得很危险。本着最大限度不修改原有代码的编码指导思想,应该对这个对象进行包装,再赋予新的对象额外的职责。就如一个步兵有杀伤敌人的功能,再把他装进战车,就额外拥有移动快、防御强的功能了。
5.3 实现
UML图:
示例代码为:
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using System;
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namespace Example
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{
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/// <summary>
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/// 示例
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/// </summary>
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class Example
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{
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/// <summary>
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/// 应用程序的主入口点。
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/// </summary>
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[STAThread]
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static void Main(string[] args)
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{
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//张三今天的计划
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Console.WriteLine( "张三今天的计划:" ) ;
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Action ZhangSan = new Eat( new Sleep( new Sport( new Action() ) ) ) ;
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ZhangSan.Act() ;
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//李四今天的计划
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Console.WriteLine( "李四今天的计划:" ) ;
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Action LiSi = new Sport( new Eat( new Sleep( new Action() ) ) ) ;
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LiSi.Act() ;
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}
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/// <summary>
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/// 主要的功能:工作
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/// </summary>
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public class Action
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{
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public virtual void Act()
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{
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Console.WriteLine( "工作……" ) ;
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}
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}
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/// <summary>
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/// 使用Decorator模式,增加额外功能:吃饭
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/// </summary>
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public class Eat : Action
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{
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private Action action = null ;
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public Eat( Action a )
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{
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action = a ;
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}
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public void EatRice()
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{
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Console.WriteLine( "吃饭……" ) ;
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}
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public override void Act()
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{
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this.EatRice() ;
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action.Act() ;
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}
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}
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/// <summary>
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/// 使用Decorator模式,增加额外功能:睡觉
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/// </summary>
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public class Sleep : Action
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{
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private Action action = null ;
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public Sleep( Action a )
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{
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action = a ;
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}
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public void Sleeping()
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{
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Console.WriteLine( "睡觉……" ) ;
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}
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public override void Act()
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{
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this.Sleeping() ;
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action.Act() ;
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}
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}
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/// <summary>
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/// 使用Decorator模式,增加额外功能:运动
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/// </summary>
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public class Sport : Action
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{
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private Action action = null ;
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public Sport( Action a )
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{
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action = a ;
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}
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public void Sporting()
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{
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Console.WriteLine( "运动……" ) ;
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}
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public override void Act()
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{
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this.Sporting() ;
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action.Act() ;
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}
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}
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}
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}
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