/// <summary>/// 抽象聚合类：AbstractObjectList/// </summary>public abstract class AbstractObjectList{protected IList<object> objectList = new List<object>();public AbstractObjectList (IList<object> objectList){this.objectList = objectList;}public void AddObject(object obj){this.objectList.Add(obj);}public void RemoveObject(object obj){this.objectList.Remove(obj);}public IList<Object> GetObjectList(){return this.objectList;}// 声明创建迭代器对象的抽象工厂方法public abstract AbstractIterator CreateIterator();}

    /// <summary>/// 具体聚合类：ProductList/// </summary>public class ProductList : AbstractObjectList{public ProductList(IList<object> objectList) : base(objectList){}public override AbstractIterator CreateIterator(){return new ProductIterator(this);}/// <summary>/// 内部类=>具体迭代器：ProductIterator/// </summary>private class ProductIterator : AbstractIterator{private ProductList productList;private IList<object> products;private int cursor1;    // 定义一个游标，用于记录正向遍历的位置private int cursor2;    // 定义一个游标，用于记录逆向遍历的位置public ProductIterator(ProductList productList){this.productList = productList;this.products = productList.GetObjectList();       // 获取集合对象this.cursor1 = 0;                                                            // 设置正向遍历游标的初始值this.cursor2 = this.products.Count - 1;                 // 设置逆向遍历游标的初始值
            }public object GetNextItem(){return products[cursor1];}public object GetPreviousItem(){return products[cursor2];}public bool IsFirst(){return cursor2 == -1;}public bool IsLast(){return cursor1 == products.Count;}public void Next(){if (cursor1 < products.Count){cursor1++;}}public void Previous(){if (cursor2 > -1){cursor2--;}}}}

    /// <summary>/// 抽象迭代器：AbstractIterator/// </summary>public interface AbstractIterator{void Next();                                  // 移动至下一个元素bool IsLast();                               // 判断是否为最后一个元素void Previous();                        // 移动至上一个元素bool IsFirst();                             // 判断是否为第一个元素object GetNextItem();           // 获取下一个元素object GetPreviousItem();   // 获取上一个元素}

    public class Program{public static void Main(string[] args){IList<object> products = new List<object>();products.Add("倚天剑");products.Add("屠龙刀");products.Add("断肠草");products.Add("葵花宝典");products.Add("四十二章经");AbstractObjectList objectList = new ProductList(products);      // 创建聚合对象AbstractIterator iterator = objectList.CreateIterator();                // 创建迭代器对象
Console.WriteLine("正向遍历");while (!iterator.IsLast()){Console.Write(iterator.GetNextItem() + ",");iterator.Next();}Console.WriteLine();Console.WriteLine("-------------------------------------------------------");Console.WriteLine("逆向遍历");while (!iterator.IsFirst()){Console.Write(iterator.GetPreviousItem() + ",");iterator.Previous();}Console.ReadKey();}}

作者：周旭龙

出处：http://edisonchou.cnblogs.com

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