组合模式,将对象组合成树形结构以表示'部分-整体'的层次结构。组合模式使得用户对单个对象和组合对象的使用具有一致性。
csharp
class Program
{
static void Main(string[] args)
{
Composite root = new Composite("root");
root.Add(new Left("Left A"));
root.Add(new Left("Left B"));
Composite comp = new Composite("Composite X");
comp.Add(new Left("Left XA"));
comp.Add(new Left("Left XB"));
root.Add(comp);
Composite comp2 = new Composite("Composite XY");
comp2.Add(new Left("Left XYA"));
comp2.Add(new Left("Left XYB"));
comp.Add(comp2);
root.Add(new Left("Left C"));
Left leaf = new Left("Left D");
root.Add(leaf);
root.Remove(leaf);
root.Display(1);
Console.ReadLine();
}
}
//Component为组合中的对象声明接口,在适当情况下,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Component的子部件
abstract class Component
{
protected string name;
public Component(string name)
{
this.name = name;
}
public abstract void Add(Component c);
public abstract void Remove(Component c);
public abstract void Display(int depth);
}
/// <summary>
/// Leaf在组合中表示叶节点对象,叶节点没有子节点
/// </summary>
class Left : Component
{
public Left(string name) : base(name)
{
}
public override void Add(Component c)//由于叶子没有再增加分枝和树叶,所以Add和Remove方法实现它没有意义,但这样做可以消除叶节点和枝节点对象在抽象层次的区别,它们具有完全一致的接口
{
Console.WriteLine("Cannot add to leaf");
}
public override void Display(int depth)
{
Console.WriteLine(new String('-',depth)+name);
}
public override void Remove(Component c)
{
Console.WriteLine("Cannot remove from a leaf");
}
}
/// <summary>
/// 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
/// </summary>
class Composite : Component
{
private List<Component> children = new List<Component>();
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)
{
Console.WriteLine(new String('-',depth)+name);
foreach (Component component in children)
{
component.Display(depth + 2);
}
}
}