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5.3 结构图

大B:“下面是组合模式的结构图如图5-1所示。”

图5-1 结构图

大B:“组合模式为组合中的对象声明接口,在适当的情况下,实现所有类共有接口的默认行为。声明一个接口用于访问和管理组合模式的子部件。”

abstract class Component
{
protected string name;
public Component(string name)
{
this.name=name;
}
public abstract void Add(component c);//通常都用Add和Remove方法来提供增加或移出树叶或树枝的功能
public abstract void Remove(Component c);
public abstract void Display(in depth);
}

Leaf在组合中表示叶节点对象,叶节点没有子节点

class Leaf:Component
{
public Leaf(string name):base(name)
{}
public override void Add(Component c)
//由于叶节点没有再增加分枝和树叶,所以Add和Remove方法实现
{
Console.WriteLine("Cannot add to a leaf");
//它没有意义,但这样可以消除叶节点和枝节点对象在抽象层次的区别
}                                           // 它们具备完全一致的接口
public override void Remove(Component c)
{
Console.WriteLine("Cannot remove to a leaf");
}
public override void Display(int depth)
{
//叶节点的具体方法,此处是显示其名称和级别
Console.WriteLine();
}
}

Composite定义有枝节点行为,用来存储子部件,在Component接口中实现与子部件有关的操作,比如增加Add和删除Remove

class Composite:Component
{
private List children=new List();
public Composite(string name):base(name)
{}
public override void Add(Component c)
{
children.add(c);
}
public override void Remove(Component c)
{
children.Remove(c);
}
public override void Display(int depth)
{ //显示枝节点名称,并对其下级进行遍历
Console.WriteLine(new string('-',depth)+name);
foreach(Component component in children)
{
component.Display(depth+2);
}
}
}

客户端代码,能通过Component接口操作组合部件的对象

static void Main(string[] args)
{
Component root=new Component("root");
root.Add(new Leaf("Leaf A"));//生成树根root,根上长出两叶
root.Add(new Leaf("Leaf B"));//LeafA与LeafB
Composite comp=new Composite("Componsite X");
comp.Add(new Leaf("Leaf XA"));
comp.Add(new Leaf("Leaf XB"));
root.Add(comp);
Composite comp2=new Composite("Composite XY");
comp2.Add(new Leaf("Leaf XYA"));
comp2.Add(new Leaf("Leaf XYB"));
comp.Add(comp2);
//根部又长出两页LeafC和LeafD,可惜LeafD没有长牢,被风吹走了
root.Add(new Leaf("Leaf c"));
Leaf leaf=new Leaf("Leaf D");
root.Add(leaf);
root.Remove(leaf);
root,Display(1);//显示大树的样子
}

显示结果:

-root

---leaf A

---leaf B

---Composite X

-----Leaf XA

-----Leaf XB

-----Composite XY

-------Composite XYA

-------Composite XYB

---Leaf c

大B:“现在你能用代码以组合模式,试写一下我给我女朋友买生日礼物。”

小A:“OK”

代码:

using System;
using System.Collections.Generic;
using System.Text;
namespace Composite
{
interface IGift
{
void Pay();
void Add(IGift gift);
}
class GiftSingle : IGift
{
private string m_name;
public GiftSingle(string name)
{
m_name = name;
}
public void Add(IGift gift)
{
}
public void Pay()
{
Console.WriteLine("我买了" + m_name + "!hoho~~");
}
};
class GiftComposite : IGift
{
private string m_name;
List m_gifts;
public GiftComposite()
{
m_name = string.Empty;
m_gifts = new List();
}
public void Add(IGift gift)
{
m_gifts.Add(gift);
}
public void Pay()
{
foreach(IGift gift in m_gifts)
{
gift.Pay();
}
}
};
class Program
{
static void Main(string[] args)
{
//20岁生日,那时的MM还很单纯~~
Console.WriteLine("lalala~20岁生日来咯------------------------------------------");
IGift singleGift20 = new GiftSingle("手表");
singleGift20.Pay();
//22岁生日,MM变得狡诈" 了~~
Console.WriteLine("heiheihei~22岁生日来咯---------------------------------------");
IGift compositeGift22 = new GiftComposite();
//打包,打包!我要把所有喜欢的礼物打包成“一套”~
compositeGift22.Add(new GiftSingle("手机"));
compositeGift22.Add(new GiftSingle("DC"));
compositeGift22.Add(new GiftSingle("DV"));
compositeGift22.Pay();
//24岁生日………………天哪!
Console.WriteLine("hiahiahia~24岁生日来咯--------------------------------------");
//先逛商场一层~买化妆品!
IGift compositeGift24 = new GiftComposite();
//打包,打包!
compositeGift24.Add(new GiftSingle("香水"));
compositeGift24.Add(new GiftSingle("指甲油"));
compositeGift24.Add(new GiftSingle("眼影"));
//然后来到二层,看中了一套衣服~
IGift singleGift24 = new GiftSingle("衣服");
//因为只能买“一件”,所以“狡诈”的MM再次打包。。。
IGift totalGifts = new GiftComposite();
//我包,我包,我包包包!
totalGifts.Add(compositeGift24);
totalGifts.Add(singleGift24);
totalGifts.Pay();
}
}
}

大B:“嘿嘿!不错喔!” +14btPMPuechmZZEDNkbZqnRedpM6M9P7yHNKZ/r0/xBzh2GAaF7sAqx/EGWdVid

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