《Head First 设计模式》工厂模式

工厂方法模式：定义了一个创建对象的接口，但由子类决定实例化的类是哪一个。工厂方法让实例化推迟到子类。

package headfirst.factory.pizzafm;import java.util.ArrayList;public abstract class Pizza {String name;String dough;String sauce;ArrayList toppings = new ArrayList(); void prepare() {System.out.println("Preparing " + name);System.out.println("Tossing dough...");System.out.println("Adding sauce...");System.out.println("Adding toppings: ");for (int i = 0; i < toppings.size(); i++) {System.out.println("   " + toppings.get(i));}}  void bake() {System.out.println("Bake for 25 minutes at 350");} void cut() {System.out.println("Cutting the pizza into diagonal slices");}  void box() {System.out.println("Place pizza in official PizzaStore box");} public String getName() {return name;}public String toString() {StringBuffer display = new StringBuffer();display.append("---- " + name + " ----\n");display.append(dough + "\n");display.append(sauce + "\n");for (int i = 0; i < toppings.size(); i++) {display.append((String )toppings.get(i) + "\n");}return display.toString();}}  

package headfirst.factory.pizzafm;public class ChicagoStyleCheesePizza extends Pizza {public ChicagoStyleCheesePizza() { name = "Chicago Style Deep Dish Cheese Pizza";dough = "Extra Thick Crust Dough";sauce = "Plum Tomato Sauce"; toppings.add("Shredded Mozzarella Cheese");} void cut() {System.out.println("Cutting the pizza into square slices");}}

package headfirst.factory.pizzafm;public abstract class PizzaStore { abstract Pizza createPizza(String item); public Pizza orderPizza(String type) {Pizza pizza = createPizza(type);System.out.println("--- Making a " + pizza.getName() + " ---");pizza.prepare();pizza.bake();pizza.cut();pizza.box();return pizza;}}

package headfirst.factory.pizzafm;public class NYPizzaStore extends PizzaStore {Pizza createPizza(String item) {if (item.equals("cheese")) {return new NYStyleCheesePizza();} else if (item.equals("veggie")) {return new NYStyleVeggiePizza();} else if (item.equals("clam")) {return new NYStyleClamPizza();} else if (item.equals("pepperoni")) {return new NYStylePepperoniPizza();} else return null;}}

package headfirst.factory.pizzafm;public class PizzaTestDrive { 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 = chicagoStore.orderPizza("cheese");System.out.println("Joel ordered a " + pizza.getName() + "\n");pizza = nyStore.orderPizza("clam");System.out.println("Ethan ordered a " + pizza.getName() + "\n"); pizza = chicagoStore.orderPizza("clam");System.out.println("Joel ordered a " + pizza.getName() + "\n");pizza = nyStore.orderPizza("pepperoni");System.out.println("Ethan ordered a " + pizza.getName() + "\n"); pizza = chicagoStore.orderPizza("pepperoni");System.out.println("Joel ordered a " + pizza.getName() + "\n");pizza = nyStore.orderPizza("veggie");System.out.println("Ethan ordered a " + pizza.getName() + "\n"); pizza = chicagoStore.orderPizza("veggie");System.out.println("Joel ordered a " + pizza.getName() + "\n");}}

抽象工厂模式：提供一个接口，用于创建相关或依赖的家族，而不需明确指明具体类。