head first 设计模式学习随笔(9)---迭代器模式

所谓迭代器模式，就是实现一个迭代器接口，从而实现对通用对象组的遍历,而又不暴露内部结构

以下以鸭子和虫子为例说明：

 

    /// <summary>
    /// 迭代器模式接口
    /// </summary>
    public interface Iterator 
    {
        bool HasNext();
        object Next();
    }

    /// <summary>
    /// 一种带数组成员类
    /// </summary>
    public class Worms : Iterator 
    {
        string[] worms;
        int nums = -1;

        public Worms(string[] worms) 
        {
            this.worms = worms;
        }

        #region Iterator Members

        public bool HasNext()
        {
            if (worms.Length > nums + 1)
            {
                nums += 1;
                return true;
            }
            else
                return false;
        }

        public object Next()
        {
            return worms[nums];
        }

        #endregion
    }


    /// <summary>
    /// 一种带泛型成员类
    /// </summary>
    public class Duck : Iterator
    {
        List<string> ducks;
        int nums = -1;

        public Duck(List<string> ducks) 
        {
            this.ducks = ducks;
        }
        #region Iterator Members

        public bool HasNext()
        {
            if (ducks.Count > nums+1)
            {
                nums += 1;
                return true;
            }
            else
                return false;
        }

        public object Next()
        {
            return ducks[nums];
        }

        #endregion
    }


    public class Info
    {
        Worms worms;
        Duck ducks;

        public Info(Worms worms,Duck ducks)
        {
            this.worms = worms;
            this.ducks = ducks;
        }

        public void ReadIterator(string type)
        {
            if (type == "ducks")
                Read(ducks);
            if (type == "worms")
                Read(worms);
        }

        //统一遍历接口
        private void Read(Iterator i)
        {
            while(i.HasNext())
                Console.WriteLine(i.Next().ToString());
        }
    }


    class Program
    {
        static void Main(string[] args)
        {
            Worms worms = new Worms(new string[] { "毛毛虫", "鼻涕虫", "蚂蚁", "苍蝇", "蚊子", "瓢虫", "蟋蟀", "蜈蚣" });
            Duck ducks = new Duck(new List<string> { "鸳鸯", "鹅", "黄头鸭", "北京填鸭", "绿头鸭", "白头鸭", "黑鸭鸭", "白鸭鸭", "长嘴鸭", "无毛鸭" });

            Info info = new Info(worms, ducks);

            info.ReadIterator("ducks");
            Console.WriteLine("-------------华丽的分割线----------------");
            info.ReadIterator("worms");

            Console.Read();
        }
    }