简单工厂模式：
可以使用静态方法，因为这样它可以不需要创建对象，但缺点是：不能通过继承来改变创建方法的行为。
简单工厂其实不是一个设计模式，反而更像一种编程习惯。
事例：
一个披萨店,会生产各种类型的披萨，如蔬菜类、蛤蜊类、奶酪类、意大利辣肠类等。
步骤：
1）选择一种类型的披萨
2）准备、烧烤、切片、包装
UML类图
遵循的设计原则：
对修改关闭，对扩展开放
Pizza.java 披萨抽象超类
package com.jing.factory.simple; import java.util.ArrayList; public abstract class Pizza { String name; // 名字 String dough;// 面包 String sauce;// 酱料 // 佐料 ArrayList<String> topping = new ArrayList<String>(); public String getName() { return name; } public void prepare() { System.out.println("Preparing " + name); } public void bake() { System.out.println("Baking " + name); } public void cut() { System.out.println("Cutting " + name); } public void box() { System.out.println("Boxing " + 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 < topping.size(); ++i) { display.append((String) topping.get(i) + "\n"); } return display.toString(); } }CheesePizza.java 奶酷披萨
package com.jing.factory.simple; public class CheesePizza extends Pizza { public CheesePizza() { name = "Cheese Pizza"; // 奶酪 披萨 dough = "Regular Crust"; // 普通的披萨饼皮 sauce = "Marinara Pizza Sauce"; // 蕃茄酱，沙司 topping.add("Fresh Mozzarella");// 新鲜的马苏里拉奶酪 topping.add("Parmesan");// 芝士 } } ClamPizza.java 蛤蜊披萨 package com.jing.factory.simple; public class ClamPizza extends Pizza { public ClamPizza(){ name = "Clam Pizza";//蛤蜊 dough = "Thin crust";// 薄的面皮 sauce = "White garlic sauce";//白的蒜酱 topping.add("Clams"); topping.add("Grated Parmesan cheese");// 巴马干酪 } }VeggiePizza.java 蔬菜披萨
package com.jing.factory.simple; public class VeggiePizza extends Pizza { public VeggiePizza(){ name = "Veggie Pizza"; // 蔬菜 dough = "Crust"; sauce = "Marinara sauce";// 蕃茄酱 topping.add("Shredded mozzaredlla");// 意大利干酪 topping.add("Grated parmesan");// 芝士 topping.add("Diced onion");// 切丁洋葱 topping.add("Sliced mushrooms");//切片蘑菇 topping.add("Sliced red pepper");//切片红花椒 topping.add("Sliced black olives");//橄榄 } }PepperoniPizza.java 意大利辣肠披萨
package com.jing.factory.simple; public class PepperoniPizza extends Pizza { public PepperoniPizza(){ name = "Pepperoni Pizza";//意大利辣肠 dough = "Curst";// 面皮 sauce = "Marinara sauce";// 蕃茄酱 topping.add("Sliced Pepperoni");// 切片辣肠 topping.add("Sliced Onion"); // 切片洋葱 topping.add("Grated parmesan cheese");//芝士奶酪 } }SimplePizzaFactory.java 简单披萨工厂，用于生产各种披萨，它是我们唯一用来披萨类的地方
package com.jing.factory.simple; public class SimplePizzaFactory { public Pizza createPizza(String type){ Pizza pizza = null; if (type.equals("cheese")){ pizza = new CheesePizza(); } else if (type.equals("pepperoni")){ pizza = new PepperoniPizza(); } else if (type.equals("clam")){ pizza = new ClamPizza(); } else if (type.equals("veggie")){ pizza = new VeggiePizza(); } return pizza; } }PizzaStore.java 披萨店，拥有一个生产工厂，及确定种类后的生产流程
package com.jing.factory.simple; public class PizzaStore { SimplePizzaFactory factory; public PizzaStore(SimplePizzaFactory factory){ this.factory = factory; } public Pizza orderPizza(String type){ Pizza pizza; pizza = factory.createPizza(type); pizza.prepare(); pizza.bake(); pizza.cut(); pizza.box(); return pizza; } } Test.java 测试类 package com.jing.factory.simple; public class Test { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub // 生成一个披萨的生产工厂 SimplePizzaFactory factory = new SimplePizzaFactory(); // 生成一个披萨店，它保存生产工厂 PizzaStore store = new PizzaStore(factory); // 生产一个奶酪披萨 Pizza pizza = store.orderPizza("cheese"); System.out.println("we ordered a " + pizza.getName() + "\n"); // 生产一个蔬菜披萨 pizza = store.orderPizza("veggie"); System.out.println("we ordered a " + pizza.getName() + "\n"); } } 输出： Preparing Cheese Pizza Baking Cheese Pizza Cutting Cheese Pizza Boxing Cheese Pizza we ordered a Cheese Pizza Preparing Veggie Pizza Baking Veggie Pizza Cutting Veggie Pizza Boxing Veggie Pizza we ordered a Veggie Pizza
