迭代器模式

Java代码实现：

package com.freedie.iteratorpattern;

/**
 * 书籍实体类
 * @author threedie.qin
 * @date2011-10-30 @ti下午05:18:02
 */
public class Book {
	private String name;
	
	public Book(String name){
		this.name = name;
	}
	
	public String getName(){
		return this.name;
	}
}

package com.freedie.iteratorpattern;

/**
 * 迭代器接口，真正进行迭代功能的接口
 * @author threedie.qin
 * @date2011-10-30 @ti下午05:10:04
 */
public interface Iterator {
	
	public abstract boolean hasNext();
	
	public abstract Object next();
	
}

package com.freedie.iteratorpattern;

/**
 * 标示可以迭代的接口，如果某一个类需要实现迭代的功能，实现该接口即可
 * @author threedie.qin
 * @date2011-10-30 @ti下午05:09:05
 */
public interface Iteratorable {
	public abstract Iterator iterator();
}

package com.freedie.iteratorpattern;

/**
 * 书柜实体类
 * @author threedie.qin
 * @date2011-10-30 @ti下午05:18:12
 */

public class BookShelf implements Iteratorable {
	private Book[] bookArray;
	private int index = 0;
	
	public BookShelf(int arrayLength){
		bookArray = new Book[arrayLength];
	}
	
	/**
	 * 往书柜上添加书籍
	 * @param book
	 * @return
	 */
	public BookShelf appendBook(Book book){
		bookArray[index ++] = book;
		return this;
	}
	
	/**
	 * 根据索引得到书柜上的书籍
	 * @param index
	 * @return
	 */
	public Book getBookAtPosition(int index){
		return bookArray[index];
	}
	
	/**
	 * 得到书柜上的书籍的总数
	 * @return
	 */
	public int getLength(){
		return this.bookArray.length;
	}
	
	/**
	 * 得到书柜的迭代器对象
	 */
	@Override
	public Iterator iterator() {
		return new BookShelfIterator(this);
	}

}

package com.freedie.iteratorpattern;
/**
 * 书柜迭代器对象
 * @author threedie.qin
 * @date2011-10-30 @ti下午05:19:27
 */
public class BookShelfIterator implements  Iterator{
	private BookShelf bookShelf;
	private int currentIndex;
	
	 public BookShelfIterator(BookShelf bookShelf){
		 this.bookShelf = bookShelf;
		 this.currentIndex = 0;
	 }
	
	 /**
	  * 判断是否还有下一个元素
	  */
	@Override
	public boolean hasNext() {
		return this.currentIndex < bookShelf.getLength() ? true : false;
	}

	/**
	 * 返回下一个元素
	 */
	@Override
	public Object next() {
		return bookShelf.getBookAtPosition(currentIndex ++);
	}

}

package com.freedie.iteratorpattern;

/**
 * 迭代器模式测试类
 * @author threedie.qin
 * @date2011-10-30 @ti下午05:15:32
 */
public class TestIteratorPattern {

	public static void main(String[] args) {
		BookShelf bookShelf = new BookShelf(5);
		bookShelf.appendBook(new Book("Android Programming")).
						appendBook(new Book("Linux kenerl design and programming")).
							appendBook(new Book("Java multithread programming")).
								appendBook(new Book("Java net programming")).
									appendBook(new Book("html5 programming"));
		
		Iterator it = bookShelf.iterator();
		while(it.hasNext()){
			Object object = it.next();
			if(object instanceof Book){
				Book book = (Book)object;
				System.out.println(book.getName());
			}
		}
		
	}

}