设计模式 - 迭代器模式(iterator pattern) 扩展 详解

迭代器模式(iterator pattern) 扩展 详解

本文地址: http://blog.csdn.net/caroline_wendy

参考迭代器模式-Java迭代器: http://blog.csdn.net/caroline_wendy/article/details/35268931

扩展迭代器模式, 添加一个Hashtable存储的类.

具体方法:

1. Hashtable的类, 包含创建value()的迭代器(iterator).

/**
 * @time 2014年6月27日
 */
package iterator;

import java.util.Hashtable;
import java.util.Iterator;

/**
 * @author C.L.Wang
 *
 */
public class CafeMenu implements Menu {

	Hashtable<String, MenuItem> menuItems =
			new Hashtable<String, MenuItem>();

	/**
	 *
	 */
	public CafeMenu() {
		// TODO Auto-generated constructor stub
		addItem("Veggie Burger and Air Fries",
				"Veggie burger on a whole wheat bun, lettuce, tomato, and fries", true, 3.99);

		addItem("Soup of the day",
				"A cup of the the soup of the day, with a side salad", false, 3.69);

		addItem("Burrito",
				"A large burrito, with whole pinto beans, salsa, quacamole", true, 4.29);

	}

	public void addItem(String name, String description,
			boolean vegetarian, double price) {
		MenuItem menuItem = new MenuItem(name, description, vegetarian, price);
		menuItems.put(menuItem.getName(), menuItem);
	}

	/* (non-Javadoc)
	 * @see iterator.Menu#createIterator()
	 */
	@Override
	public Iterator<MenuItem> createIterator() {
		// TODO Auto-generated method stub
		return menuItems.values().iterator();
	}

}

2. 客户类(client), 调用迭代器(Iterator).

/**
 * @time 2014年6月27日
 */
package iterator;

import java.util.Iterator;

/**
 * @author C.L.Wang
 *
 */
public class Waitress {

	Menu pancakeHouseMenu;
	Menu dinerMenu;
	Menu cafeMenu;

	/**
	 *
	 */
	public Waitress(Menu pancakeHouseMenu, Menu dinerMenu, Menu cafeMenu) {
		// TODO Auto-generated constructor stub
		this.pancakeHouseMenu = pancakeHouseMenu;
		this.dinerMenu = dinerMenu;
		this.cafeMenu = cafeMenu;
	}

	public void printMenu() {
		Iterator<MenuItem> pancakeIterator = pancakeHouseMenu.createIterator();
		Iterator<MenuItem> dinerIterator = dinerMenu.createIterator();
		Iterator<MenuItem> cafeIterator = cafeMenu.createIterator();

		System.out.println("MENU\n----\nBREAKFAST");
		printMenu(pancakeIterator);
		System.out.println("\nLUNCH");
		printMenu(dinerIterator);
		System.out.println("\nDINNER");
		printMenu(cafeIterator);

	}

	private void printMenu(Iterator<MenuItem> iterator) {
		while (iterator.hasNext()) {
			MenuItem menuItem = (MenuItem)iterator.next();
			System.out.print(menuItem.getName() + ": ");
			System.out.print(menuItem.getPrice() + " -- ");
			System.out.println(menuItem.getDescription());
		}
	}

}

3. 测试:

/**
 * @time 2014年6月27日
 */
package iterator;

/**
 * @author C.L.Wang
 *
 */
public class MenuTestDrive {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		PancakeHouseMenu pancakeHouseMenu = new PancakeHouseMenu();
		DinerMenu dinerMenu = new DinerMenu();
		CafeMenu cafeMenu = new CafeMenu();

		Waitress waitress = new Waitress(pancakeHouseMenu, dinerMenu, cafeMenu);

		waitress.printMenu();
	}

}

4. 输出:

MENU
----
BREAKFAST
K&B‘s Pancake Breakfast: 2.99 -- Pancakes with scrambled eggs, and toast
Regular Pancake Breakfast: 2.99 -- Pancakes with fried eggs, sausage
Blueberry Pancakes: 3.49 -- Pancakes made with fresh blueberries
Waffles: 3.59 -- Waffles, with your choice of blueberries or strawberries

LUNCH
Vegetarian BLT: 2.99 -- (Fakin‘) Bacon with lettuce & tomato on whole wheat
BLT: 2.99 -- Bacon with lettuce & tomato on the whole wheat
Soup of the day: 3.29 -- Soup of the day, with a side of potato salad
Hotdog: 3.05 -- A hot dog, with saurkraut, relish, onions, topped with cheese

DINNER
Soup of the day: 3.69 -- A cup of the the soup of the day, with a side salad
Burrito: 4.29 -- A large burrito, with whole pinto beans, salsa, quacamole
Veggie Burger and Air Fries: 3.99 -- Veggie burger on a whole wheat bun, lettuce, tomato, and fries

5. 其余代码参考: http://blog.csdn.net/caroline_wendy/article/details/35268931

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