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 {@Overridepublic Dough CreateDoufh() {return new Dough("ThinCrust");}@Overridepublic Sauce CreateSauce() {return new Sauce("Marinara");}@Overridepublic Cheese CreateCheese() {return new Cheese("Reggiano");}@Overridepublic Veggies[] CreateVeggies() {Veggies veggies[] = {new Veggies("Garlic"), new Veggies("Onion"), new Veggies("Mushroom")};return veggies;}@Overridepublic Clams CreateClams() {return new Clams("Fresh");}}

芝加哥原料加工厂

ChicagoPizzaIngredientFactory.java

public class ChicagoPizzaIngredientFactory implements PizzaIngredientFactory {@Overridepublic Dough CreateDoufh() {return new Dough("ThinCrust");}@Overridepublic Sauce CreateSauce() {return new Sauce("PlumTomato");}@Overridepublic Cheese CreateCheese() {return new Cheese("Mozzarella");}@Overridepublic Veggies[] CreateVeggies() {Veggies veggies[] = {new Veggies("BlackOlives"), new Veggies("EggPlant"), new Veggies("Spinach")};return veggies;}@Overridepublic 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;}@Overridepublic 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;}@Overridepublic 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 {@Overrideprotected 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 {@Overrideprotected 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》