设计模式之--组合模式

组合模式：是将对象组合成树形结构一表示“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。

组合模式示例代码如下：

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 Y");
            root.Add(new Left("Left yA"));
            root.Add(new Left("Left yB"));
            comp.Add(comp2);

            root.Display(1);
            Console.Read();
        }
    }
    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);

    }
    class Left:Component
    {
        public Left(string name):base(name)
        {

        }
        public override void Add(Component c)
        {
            Console.WriteLine("Cannot add to a left");
        }

        public override void Display(int depth)
        {
            Console.WriteLine(new string('-', depth) + name);
        }

        public override void Remove(Component c)
        {
            Console.WriteLine("Cannot remove from a left");
            
        }
    }
    class Composite : Component
    {
        private List<Component> childComponet = new List<Component>();
        public Composite(string name):base(name)
        {

        }
        public override void Add(Component c)
        {
            childComponet.Add(c);
        }

        public override void Display(int depth)
        {
            Console.WriteLine(new string('-', depth) + name);
            foreach(Component component in childComponet)
            {
                component.Display(depth + 2);
            }
        }

        public override void Remove(Component c)
        {
            childComponet.Remove(c);
        }
    }

何时使用组合模式：

需求中体现部分与整体层次的结构时，以及希望用户可以忽略组合对象与单个对象的不同，统一的使用组合结构中的所有对象时，就应该考虑使用组合模式。

 

 

Component：组合中的对象声明接口，在适当情况下，实现所有类共有的默认行为。声明一个接口用于访问和管理Component的子部件。

Composite：定义由枝节点行为，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。

Left：在组合中表示叶节点对象，叶节点没有子节点。

 

实例

 abstract class Company
    {
        protected string name;
        public Company(string name)
        {
            this.name = name;
        }
        public abstract void Add(Company C);
        public abstract void Remove(Company c);
        public abstract void Display(int depth);
        public abstract void LineOfDuty();//履行职责
    }
    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 Display(int depth)
        {
            Console.WriteLine(new string('-', depth) + name);
            foreach(Company com in children)
            {
                com.Display(depth + 2);
            }
        }

        public override void LineOfDuty()
        {
            foreach(Company com in children)
            {
                com.LineOfDuty();
            }
        }

        public override void Remove(Company c)
        {
            children.Remove(c);
        }
    }

    class HRDepartment : Company
    {
        public override void Add(Company C)
        {
            throw new NotImplementedException();
        }
        public HRDepartment(string name):base(name)
        {

        }
        public override void Display(int depth)
        {
            Console.WriteLine(new string('-', depth) + name);
        }

        public override void LineOfDuty()
        {
            Console.WriteLine("{0} 员工招聘培训管理", name);
        }

        public override void Remove(Company c)
        {
            throw new NotImplementedException();
        }
    }
    class FinanceDepartment:Company
    {
        public FinanceDepartment(string name):base(name)
        {

        }

        public override void Add(Company C)
        {
            throw new NotImplementedException();
        }

        public override void Display(int depth)
        {
            Console.WriteLine(new string('-', depth) + name);
        }

        public override void LineOfDuty()
        {
            Console.WriteLine("{0} 公司财务收支管理", name);
        }

        public override void Remove(Company c)
        {
            throw new NotImplementedException();
        }
    }

 

ConcreteCompany root = new ConcreteCompany("北京总部");
            root.Add(new HRDepartment("总公司人力资源部"));
            root.Add(new FinanceDepartment("总公司财务部"));

            ConcreteCompany root2 = new ConcreteCompany("上海华东分公司");
            root2.Add(new HRDepartment("华东分公司人力资源部"));
            root2.Add(new FinanceDepartment("华东分公司财务部"));
            root.Add(root2);
            root.Display(1);
            Console.Read();