设计模式学习笔记--迭代器模式

using System;

namespace Iterator
{
    /// <summary> 
    /// 作者：bzyzhang
    /// 时间：2016/5/30 20:01:24 
    /// 博客地址：http://www.cnblogs.com/bzyzhang/
    /// Iterator说明：迭代器抽象类
    /// </summary> 
    public abstract class Iterator
    {
        public abstract object First();
        public abstract object Next();
        public abstract bool IsDone();
        public abstract object CurrentItem();
    }
}

using System;

namespace Iterator
{
    /// <summary> 
    /// 作者：bzyzhang
    /// 时间：2016/5/30 20:03:19 
    /// 博客地址：http://www.cnblogs.com/bzyzhang/
    /// Aggregate说明：聚集抽象类 
    /// </summary> 
    public abstract class Aggregate
    {
        public abstract Iterator CreateIterator();
    }
}

using System;
using System.Collections.Generic;

namespace Iterator
{
    /// <summary> 
    /// 作者：bzyzhang
    /// 时间：2016/5/30 20:06:13 
    /// 博客地址：http://www.cnblogs.com/bzyzhang/
    /// ConcreteAggregate说明：具体聚集类，继承Aggregate
    /// </summary> 
    public class ConcreteAggregate:Aggregate
    {
        private List<object> items = new List<object>();

        public override Iterator CreateIterator()
        {
            return new ConcreteIterator(this);
        }

        public int Count
        {
            get
            {
                return items.Count;
            }
        }

        public object this[int index]
        {
            get
            {
                return items[index];
            }
            set
            {
                items.Insert(index,value);
            }
        }
    }
}

using System;

namespace Iterator
{
    /// <summary> 
    /// 作者：bzyzhang
    /// 时间：2016/5/30 20:04:19 
    /// 博客地址：http://www.cnblogs.com/bzyzhang/
    /// ConcreteIterator说明：具体迭代器类，继承Iterator
    /// </summary> 
    public class ConcreteIterator:Iterator
    {
        private ConcreteAggregate aggregate;
        private int current = 0;

        public ConcreteIterator(ConcreteAggregate aggregate)
        {
            this.aggregate = aggregate;
        }

        public override object First()
        {
            return aggregate[0];
        }

        public override object Next()
        {
            object ret = null;
            ++current;
            if(current <aggregate.Count)
                ret = aggregate[current];
            return ret;
        }

        public override bool IsDone()
        {
            return current >= aggregate.Count ? true : false;
        }

        public override object CurrentItem()
        {
           return aggregate[current];
        }
    }
}

using System;

namespace Iterator
{
    class Program
    {
        static void Main(string[] args)
        {
            ConcreteAggregate a = new ConcreteAggregate();

            a[0] = "大鸟";
            a[1] = "小菜";
            a[2] = "行李";
            a[3] = "老外";
            a[4] = "公交内部员工";
            a[5] = "小偷";

            Iterator iterator = new ConcreteIterator(a);

            object item = iterator.First();

            while (!iterator.IsDone())
            {
                Console.WriteLine("{0}请买车票！",iterator.CurrentItem());
                iterator.Next();
            }
        }
    }
}