抽象工厂模式

定义：提供一个接口， 用于创建相关或依赖对象的家族， 而不需要具体类；

抽象工厂模式允许客户使用抽象的接口来创建一组相关的产品， 而不需要知道或关系实际产出的具体产品是什么， 这样一来， 客户就从具体的产品中被解耦。

抽象工厂模式是从前面的工厂方法模式演变而来。 依然由pizzaStore来举例。  我们从原料入手， 每种pizza的制作方法和流程都一样， 由pizza类控制， 不同是各种原料。 比如cheesePizza，原料有：Sauce、Dough， Cheese；  对于不同地区， 原料风味不同，如纽约风味的cheesePizza：MarinaraSauce、ThinCrustDough、ReggianoCheese， 芝加哥风味的cheesePizza：PlumTomatoSauce、ThinCrustDough、MozzarellaCheese；

现在我们要建造一个工厂来生产原料， 这个工厂负责创建原料家族中的每一种原料。 接下来我们在程序中来处理各个区域的差异。

1、原料生产工厂：

PizzaIngredientFactory.java

Dough、Sauce、Cheese、Veggies、Clams这几个是原料类。 

public interface PizzaIngredientFactory {
	public Dough CreateDoufh();
	public Sauce CreateSauce();
	public Cheese CreateCheese();
	public Veggies[] CreateVeggies();
	public Clams CreateClams();
}

纽约原料加工厂

NYPizzaIngredientFactory.java

public class NYPizzaIngredientFactory implements PizzaIngredientFactory {

	@Override
	public Dough CreateDoufh() {
		return new Dough("ThinCrust");
	}

	@Override
	public Sauce CreateSauce() {
		return new Sauce("Marinara");
	}

	@Override
	public Cheese CreateCheese() {
		return new Cheese("Reggiano");
	}

	@Override
	public Veggies[] CreateVeggies() {
		Veggies veggies[] = {new Veggies("Garlic"), new Veggies("Onion"), new Veggies("Mushroom")};
		return veggies;
	}

	@Override
	public Clams CreateClams() {
		return new Clams("Fresh");
	}
	
	
}

芝加哥原料加工厂

ChicagoPizzaIngredientFactory.java

public class ChicagoPizzaIngredientFactory implements PizzaIngredientFactory {

	@Override
	public Dough CreateDoufh() {
		return new Dough("ThinCrust");
	}

	@Override
	public Sauce CreateSauce() {
		return new Sauce("PlumTomato");
	}

	@Override
	public Cheese CreateCheese() {
		return new Cheese("Mozzarella");
	}

	@Override
	public Veggies[] CreateVeggies() {
		Veggies veggies[] = {new Veggies("BlackOlives"), new Veggies("EggPlant"), new Veggies("Spinach")};
		return veggies;
	}

	@Override
	public Clams CreateClams() {
		return new Clams("Frozen");
	}
	
	
}

2、pizza类

1)、pizza基础类：pizza.java

public abstract class Pizza {
	protected String name;
	protected Dough dough;
	protected Sauce sauce;
	protected Veggies veggies[];
	protected Cheese cheese;
	protected Clams clam;
	
	public abstract void Prepare();
		
	
	public void bake() {
		System.out.println("Bake for 25 minutes at 350");
	}
	
	public void cut() {
		System.out.println("Cutting the pizza into diagonal slices");
	}
	
	public void box() {
		System.out.println("Place pizza in official PizzaStore box ");
	}
	
	public void setName(String name) {
		this.name = name;
	}
	
	public String getName() {
		return name;
	}
}

2)、CheesePizza.java

我们通过制定PizzaIngredientFactory来制定口味

public class CheesePizza extends Pizza {
	PizzaIngredientFactory ingredientFactory;

	public CheesePizza (PizzaIngredientFactory ingredientFactory) {
		this.ingredientFactory = ingredientFactory;
	}
	
	@Override
	public void Prepare() {// 这里的原料是根据口味，不同的区域工厂生产提供
		System.out.println("Preparing " + name);
		System.out.println("ingredient:");  
		dough = ingredientFactory.CreateDoufh();
		sauce = ingredientFactory.CreateSauce();
		cheese = ingredientFactory.CreateCheese();
	}
}

3）、VeeggiePizza.java

public class VeggiePizza extends Pizza {
	PizzaIngredientFactory ingredientFactory;

	public VeggiePizza (PizzaIngredientFactory ingredientFactory) {
		this.ingredientFactory = ingredientFactory;
	}
	
	@Override
	public void Prepare() {
		System.out.println("Preparing " + name);
		dough = ingredientFactory.CreateDoufh();
		sauce = ingredientFactory.CreateSauce();
		cheese = ingredientFactory.CreateCheese();
		veggies = ingredientFactory.CreateVeggies();
	}
}

其他的ClamPizza等省略， 与上面实现方法相同；

3、pizzaStore

1)、抽象类PizzaStore.java

public abstract class PizzaStore {
	
	public Pizza orderPizza(String type) {
		Pizza pizza;
		pizza = createPizza(type);
		pizza.Prepare();
		pizza.bake();
		pizza.cut();
		pizza.box();
		return pizza;
	}
	
	protected abstract Pizza createPizza(String type);
}

2)NYPizzaStore.java

public class NYPizzaStore extends PizzaStore {

	@Override
	protected Pizza createPizza(String type) {
		Pizza pizza = null;
		PizzaIngredientFactory ingredientFactory = new NYPizzaIngredientFactory();
		if (type.equals("cheese")) {
			pizza = new CheesePizza(ingredientFactory);
			pizza.setName("New York Style Cheese Pizza");
		}else if (type.equals("veggie")) {
			pizza = new VeggiePizza(ingredientFactory);
			pizza.setName("New York Style Veggie Pizza");
		}else if (type.equals("clam")) {
			pizza = new ClamPizza(ingredientFactory);
			pizza.setName("New York Style ClamP Pizza");
		}	
		return pizza;
	}
}

3)ChicagoPizzaStore.jva

public class ChicagoPizzaStore extends PizzaStore {

	@Override
	protected Pizza createPizza(String type) {
		Pizza pizza = null;
		PizzaIngredientFactory ingredientFactory = new ChicagoPizzaIngredientFactory();
		if (type.equals("cheese")) {
			pizza = new CheesePizza(ingredientFactory);
			pizza.setName("Chicago Style Cheese Pizza");
		}else if (type.equals("veggie")) {
			pizza = new VeggiePizza(ingredientFactory);
			pizza.setName("Chicago Style Veggie Pizza");
		}else if (type.equals("clam")) {
			pizza = new ClamPizza(ingredientFactory);
			pizza.setName("Chicago Style ClamP Pizza");
		}	
		return pizza;
	}
}

4、测试程序

PizzaMain.java

public class PizzaMain {
	public static void main(String[] args) {
		PizzaStore nyStore = new NYPizzaStore();
		PizzaStore chicagoStore = new ChicagoPizzaStore();
		
		Pizza pizza = nyStore.orderPizza("cheese");
		System.out.println("Ethan ordered a" + pizza.getName() + "\n");
		
		Pizza pizza2 = chicagoStore.orderPizza("cheese");
		System.out.println("Joel ordered a" + pizza2.getName() + "\n");
		
		Pizza pizza3 = chicagoStore.orderPizza("veggie");
		System.out.println("Lucy ordered a" + pizza3.getName() + "\n");
	}
}

参考：《Head First设计模式》