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：

 

Code

   
      /// <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();
 }
 }