结构型模式之 组合模式 笔记

组合模式（透明）：

示例性图例：

课堂回忆：怎么说呢？就是好像要建链表一样，为了要使得链表元素能够继续充当链表(大不了充当子链表的头指针)为了使得客户端能够把复杂的图像当做基础元素做，那就要使得基础元素能够对子元素进行操作。为什么是透明的（看不出来的意思）呢：因为如果到了叶子节点的时候，已经没有子"链表"了，此时确切而言，已经没有add,Remove，Getchild方法了，但是这里明显有可能会误用到，虽然客户端不会……这里回忆的怪怪的，很有问题，感觉还有查阅很多资料才行啊。

 

示例性代码：

public abstract class Graphics
{
    protected string _name;

    public Graphics(string name)
    {
        this._name = name;
    }
    public abstract void Draw();
    public abstract void Add();
    public abstract void Remove();
}

public class Picture : Graphics
{
    protected ArrayList picList = new ArrayList();

    public Picture(string name)
        : base(name)
    { }
    public override void Draw()
    {
        Console.WriteLine("Draw a" + _name.ToString());

        foreach (Graphics g in picList)
        {
            g.Draw();
        }
    }

    public override void Add(Graphics g)
    {
        picList.Add(g);
    }
    public override void Remove(Graphics g)
    {
        picList.Remove(g);
    }
}

public class Line : Graphics
{
    public Line(string name)
        : base(name)
    { }

    public override void Draw()
    {
        Console.WriteLine("Draw a" + _name.ToString());
    }
    public override void Add(Graphics g)
    { }
    public override void Remove(Graphics g)
    { }
}

public class Circle : Graphics
{
    public Circle(string name)
        : base(name)
    { }

    public override void Draw()
    {
        Console.WriteLine("Draw a" + _name.ToString());
    }
    public override void Add(Graphics g)
    { }
    public override void Remove(Graphics g)
    { }
}

public class Rectangle : Graphics
{
    public Rectangle(string name)
        : base(name)
    { }

    public override void Draw()
    {
        Console.WriteLine("Draw a" + _name.ToString());
    }
    public override void Add(Graphics g)
    { }
    public override void Remove(Graphics g)
    { }
}

 

安全式组合模式：

 

示意性图例：

课堂回忆：这下子，管理子对象的方法放在创建树枝的picture当中，这样就安全了。叶子节点不会用到这些非叶子节点才用的到的方法。

 

示例性代码：

public abstract class Graphics
{
    protected string _name;

    public Graphics(string name)
    {
        this._name = name;
    }
    public abstract void Draw();
}

public class Picture : Graphics
{
    protected ArrayList picList = new ArrayList();

    public Picture(string name)
        : base(name)
    { }
    public override void Draw()
    {
        Console.WriteLine("Draw a" + _name.ToString());//边递归下去，边输出结果 

        foreach (Graphics g in picList)
        {
            g.Draw();//这个是核心啊。 
        }
    }

    public void Add(Graphics g)
    {
        picList.Add(g);
    }
    public void Remove(Graphics g)
    {
        picList.Remove(g);
    }
}

public class Line : Graphics
{
    public Line(string name)
        : base(name)
    { }

    public override void Draw()
    {
        Console.WriteLine("Draw a" + _name.ToString());
    }
}

public class Circle : Graphics
{
    public Circle(string name)
        : base(name)
    { }

    public override void Draw()
    {
        Console.WriteLine("Draw a" + _name.ToString());
    }
}

public class Rectangle : Graphics
{
    public Rectangle(string name)
        : base(name)
    { }

    public override void Draw()
    {
        Console.WriteLine("Draw a" + _name.ToString());
    }
}
public class App
{
    public static void Main()
    {
        Picture root = new Picture("Root");

        root.Add(new Line("Line"));
        root.Add(new Circle("Circle"));

        Rectangle r = new Rectangle("Rectangle");
        root.Add(r);

        root.Draw();
    }
}