• 組合模式
  將對象組合成樹形結(jié)構(gòu)以表示"部分-整體"的層次結(jié)構(gòu)。組合模式是的用戶對單個對象和組合對象的使用具有一致性。

//對象的聲明接口
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);
}
//葉子
class Leaf:Component
{
    public Leaf(string name)
    :base(name)
    {}
    public override void Add(Component c)
    {
        Console.WriteLine("Cannot add to a leaf");
    }
        public override void Remove(Component c)
    {
        Console.WriteLine("Cannot Remove from a leaf");
    }

    public override void Display(int depth)
    {
        Console.WriteLine(new String('-',depth)+name);
    }
}
//樹枝
class Composite:Component
{
    //1.聲明組件數(shù)組
    private List<Component>children = new List<Component>();
    public Component(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);
        }
    }
}
//客戶端調(diào)用
static void Main(string[] args)
{
    //1.聲明主干組件,并添加兩個葉子
    Composite root = new Composite("root");
    root.Add(new Leaf("Leaf A"));
    root.Add(new Leaf("Leaf B"));
    //2.添加分支,并給分支添加葉子，將分支添加到主干上
    Composite comp = new Composite("Composite X");
    comp.Add(new Leaf("Leaf XA"));
    comp.Add(new Leaf("Leaf XB"));
    root.Add(comp);
    //3.添加分支,并給分支添加葉子，將分支添加到主干上
    Composite comp2 = new Composite("Composite XY");
    comp2.Add(new Leaf("Leaf XYA"));
    comp2.Add(new Leaf("Leaf XYB"));
    root.Add(comp2);
    //顯示總的樣式
    root.Display(1);
    Console.Read();
}

• 透明方式與安全方式

  • 透明模式：葉節(jié)點與枝節(jié)點對于外界是沒有分別的，它們具備對外一致的接口。但是問題也是很明顯，因為Leaf 類本身不具備 Add(),Remove() 方法的功能，所以實現(xiàn)它是沒有意義的。
  • 安全模式：Component 接口中不去聲明 Add() 和 Remove() 方法，那么子類的 Leaf 就不需要去實現(xiàn)它，而是在 Composite 聲明所有用來管理子類對象的方法，不過由于不夠透明，所以樹葉和樹枝類將不具有相同的接口。客戶端的調(diào)用需要相應(yīng)的判斷，帶來的不便。

• 實際應(yīng)用

abstract class Company
{
    protected string name;
    public Company(string name)
    {
        this.name = name;
    }
    public abstract void Add(Company c);//添加
    public abstract void Remove(Company c);//減少
    public abstract void Display(Company c);//展示
    public abstract void LineOfDuty();//履行職責
}
class ConcreteCompany : Company
{
    private List<Company>children = new List<Company>();
    public ConcreteCompany(string name):base(name)
    {}
    public override void Add(Company c){
        children.Add(c);
    }
    public override void Remove(Company c)
    {
        children.Remove(c);
    }
    public override void Display(int depth)
    {
        Console.WriteLine(new string('-',depth)+name);
        foreach (Company component in children)
        {
            component.Display(depth + 2);
        }
    }
    public override void LineOfDuty()
    {
        foreach(Company component in children)
        {
            component.LineOfDuty();
        }
    }
}
class HRDepartment : Company
{
    public HRDepartment(string name):base(name){}
    public override void Add(Company c){
    }
    public override void Remove(Company c)
    ｛｝
    public override void Display()
    {
        Console.WriteLine(new String('-',depth) + name);
    }
    public override void LineOfDuty()
    {
        Console.WriteLine("{0}",name);
    }
}
class FinanceDepartment :Company
{
    public FinanceDepartment(string name):base(name)
    {}
    public override void Add(){}
    public override void Remove(){}
    public override void Display()
    {
        Console.WriteLine(new String('-',depth)+ name);
    }
    public override void LineOfDuty()
    {
        Console.WriteLine("{0}",name);
    }
}
static void Main(string[] args)
{
    ConcreteCompany root = new ConcreteCompany("總公司");
    root.Add(new HRDepartment("hr"));
    root.Add(new FinanceDepartment("Final"));
    ConcreteCompany comp = new ConcreteCompany("上海分公司");
    comp.Add(new HRDepartment("hr"));
    comp.Add(new FinanceDepartment("Final"));
    root.Add(comp);
    ConcreteCompany com1 = new ConcreteCompany("沈陽辦事處");
    com1.Add(new HRDepartment("hr"));
    com1.Add(new FinanceDepartment("Final"));
    comp.Add(com1);
    ConcreteCompany com2 = new ConcreteCompany("大連辦事處");
    com2.Add(new HRDepartment("hr"));
    com2.Add(new FinanceDepartment("Final"));
    comp.Add(com2);
    Console.WriteLine("\n 結(jié)構(gòu)圖:")
        root.Display(1);
    Console.WriteLine("\nDuty:")
        root.LineOfDuty();
    Console.Read();
}