迭代器模式

雨点打透心脏的1/2处 2021-09-17 00:04 555阅读 0赞

## 16.迭代器模式 ##

![70][]

class Program
        {
            static void Main(string[] args)
            {
                ConcreteAggregate monkey = new ConcreteAggregate();
                monkey[0] = "猴子";
                monkey[1] = "刘木同";
                monkey[2] = "笨蛋";
                monkey[3] = "小弟";
                monkey[4] = "领导";
                monkey[5] = "内部人员";
                monkey[6] = "小偷";
    
                Iterator i = new ConcreteIterator(monkey);
                object item = i.First();//从第一个乘客开始
                while (!i.IsDone())
                {
                    Console.WriteLine("{0}请买火车票", i.CurrentItem());//若没买票，请补票
                    i.Next();//遍历下一个
                }
                Console.Read();
            }
        }
        abstract class Iterator
        {
            public abstract object First();//1开始对象
            public abstract object Next();//2得到下一个对象
            public abstract bool IsDone();//3判断是否到结尾
            public abstract object CurrentItem();//4当前对象
        }
        abstract class Aggregate//聚集抽象类
        {
            public abstract Iterator CreateIterator();//创建迭代器
        }
        class ConcreteIterator : Iterator//具体迭代器类
        {
            private ConcreteAggregate aggregate;//定义一个具体聚集对象
            private int current = 0;
            public ConcreteIterator(ConcreteAggregate aggregate)
            {
                this.aggregate = aggregate;//初始化时将具体的聚集对象传入
            }
            public override object First()//得到聚集的第一个对象
            {
                return aggregate[0];
            }
            public override object Next()//得到聚集的下一个对象
            {
                object ret = null;
                current++;
                if (current < aggregate.Count)
                {
                    ret = aggregate[current];
                }
                return ret;
            }
            public override bool IsDone()//判断当前是否遍历到结尾，到结尾返回true
            {
                return current >= aggregate.Count ? true : false;
            }
            public override object CurrentItem()
            {
                return aggregate[current];//返回当前的聚集对象
            }
        }  
        class ConcreteAggregate : Aggregate//具体聚集类
        {
            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); }
            }
        }

![70 1][]

[70]: /images/20210725/abd8279ea601469f84c94c4adde6ff7e.png
[70 1]: /images/20210725/b87772a71b0d4cbdb936c2420c959d61.png