设计模式之组合模式

组合模式:将对象聚合成树形结构来表现“整体/部分”的层次结构。
组合模式能让客户以一致的方式来处理个别对象以及对象组合。
也就是我们可以忽略对象组合与个体对象之间的差别

一、餐厅菜单项目

二、代码

1、超类MenuComponent

public abstract class MenuComponent {

	public String getName() {
		return "";
	}

	public String getDescription() {
		return "";
	}

	public float getPrice() {
		return 0;
	}

	public boolean isVegetable() {
		return false;
	}

	public abstract void print();

	public Iterator getIterator() {
		return new NullIterator();
	}
}

2、CakeHouseMenu

public class CakeHouseMenu extends MenuComponent {
	private ArrayList<MenuComponent> menuItems;

	public CakeHouseMenu() {
		menuItems = new ArrayList<MenuComponent>();

		addItem("KFC Cake Breakfast", "boiled eggs&toast&cabbage", true, 3.99f);
		addItem("MDL Cake Breakfast", "fried eggs&toast", false, 3.59f);
		addItem("Stawberry Cake", "fresh stawberry", true, 3.29f);
		addItem("Regular Cake Breakfast", "toast&sausage", true, 2.59f);
	}

	private void addItem(String name, String description, boolean vegetable, float price) {
		MenuItem menuItem = new MenuItem(name, description, vegetable, price);
		menuItems.add(menuItem);
	}

	public Iterator getIterator() {
		return new ComposeIterator(menuItems.iterator());
	}

	@Override
	public void print() {
		System.out.println("****This is CakeHouseMenu****");
	};
}

3、DinerMenu

public class DinerMenu extends MenuComponent {
	private final static int Max_Items = 5;
	private int numberOfItems = 0;
	private MenuComponent[] menuItems;

	public DinerMenu() {
		menuItems = new MenuComponent[Max_Items];
		addItem("vegetable Blt", "bacon&lettuce&tomato&cabbage", true, 3.58f);
		addItem("Blt", "bacon&lettuce&tomato", false, 3.00f);
		addItem("bean soup", "bean&potato salad", true, 3.28f);
		addItem("hotdog", "onions&cheese&bread", false, 3.05f);
		addSubMenu(new SubMenu());
	}

	private void addItem(String name, String description, boolean vegetable, float price) {
		MenuItem menuItem = new MenuItem(name, description, vegetable, price);
		if (numberOfItems >= Max_Items) {
			System.err.println("sorry,menu is full!can not add another item");
		} else {
			menuItems[numberOfItems] = menuItem;
			numberOfItems++;
		}
	}
	
	private void addSubMenu(MenuComponent mMenuComponent) {
		if (numberOfItems >= Max_Items) {
			System.err.println("sorry,menu is full!can not add another item");
		} else {
			menuItems[numberOfItems] = mMenuComponent;
			numberOfItems++;
		}
	}
}

4、SubMenu

public class SubMenu extends MenuComponent {
	private ArrayList<MenuComponent> menuItems;

	public SubMenu() {
		menuItems = new ArrayList<MenuComponent>();

		addItem("Apple Cookie", "Apple&candy&Cookie", true, 1.99f);
		addItem("Banana Cookie", "Banana&candy&Cookie", false, 1.59f);
		addItem("Orange Cookie", "Orange&Cookie", true, 1.29f);
	}

	private void addItem(String name, String description, boolean vegetable,float price) {
		MenuItem menuItem = new MenuItem(name, description, vegetable, price);
		menuItems.add(menuItem);
	}

	public Iterator getIterator() {
		return new ComposeIterator(menuItems.iterator());
	}

	@Override
	public void print() {
		System.out.println("****This is SubMenu****");
	};	
}

5、MenuItem

public class MenuItem extends MenuComponent{
	private String name,description;
	private boolean vegetable;
	private float price;
	public MenuItem(String name,String description,boolean vegetable,float price){
		this.name=name;
		this.description=description;
		this.vegetable=vegetable;
		this.price=price;	
	}
	@Override
	public String getName()
	{
		return name;
	}
	@Override
	public String getDescription()
	{
		return description;
	}
	@Override
	public float getPrice()
	{
		return price;
	}
	@Override
	public boolean  isVegetable()
	{
		return vegetable;
	}
	@Override
	public void print() {
		System.out.println(getName() + "***" + getPrice() + "***" + getDescription());
	}
}