设计模式之迭代器模式(Iterator)

迭代器模式(Iterator)：提供一种方法顺序访问一个聚合对象中各个元素，而不是暴露对象的内部表示。
1.访问一个聚焦对象，而且不管这些对象是什么都需要遍历的时候。

Iterator1.cs

using System;
using System.Collections.Generic;
using System.Text;

//迭代器模式(Iterator)：提供一种方法顺序访问一个聚合对象中各个元素，而不是暴露对象的内部表示。
//1.访问一个聚焦对象，而且不管这些对象是什么都需要遍历的时候。
namespace Iterator
{
    class Iterator1
    {
    }

    //Iterator
    abstract class Iterator
    {
        public abstract object First();
        public abstract object Next();
        public abstract bool IsDone();
        public abstract object Currenttime();
    }
    //Aggregate
    abstract class Aggregate
    {
        public abstract Iterator CreateIterator();
    }
    //ConcreteIterator
    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 Currenttime()
        {
            return aggregate[current];
        }
    }
    //ConcreteArrregate
    class ConcreteAggregate : Aggregate
    {
        private IList<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); }
        }
    }

}

Program.cs

using System;
using System.Collections.Generic;
using System.Text;

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

            a[0] = "A";
            a[1] = "B";
            a[2] = "C";
            a[3] = "D";
            a[4] = "E";
            a[5] = "F";

            Iterator i = new ConcreteIterator(a);
            object item = i.First();
            while (!i.IsDone())
            {
                Console.WriteLine("{0} 你好", i.Currenttime());
                i.Next();
            }

            Console.Read();
        }
    }
}

运行结果：

A 你好

B 你好

C 你好

D 你好

E 你好

F 你好