1-4 工厂模式（工厂方法模式/抽象工厂模式）

工厂模式

工厂模式概念解释需求1 普通实现简单工厂产生具体披萨披萨店调用工厂做出具体披萨工厂方法模式简单工厂与工厂方法的区别需求2 保证风味种类或者说原料都得是指定的抽象工厂模式工厂方法和抽象工厂的区别

注意：接口：泛指狭义上的接口，也可以指抽象类

概念解释

工厂方法模式：

定义一个创建对象的接口，但由子类决定实例化的具体类型。即，将类的实例化推迟到了子类。抽象工厂模式

提供一个接口，用于创建相关或依赖对象的家族。也是吧类的实例推迟到了子类

具体区别下文会有介绍。

简单工厂的方式不是设计模式，更多的是一种编码规范。

需求1

创建一个不同地区（纽约、芝加哥）风味的披萨点生产的不同种类（ chessse veggie）披萨

1 普通实现

// 披萨店直接做具体类型的披萨耦合性极大public class DependentPizzaStore {public Pizza createPizza(String style, String type) {Pizza pizza = null;if (style.equals("NY")) {if (type.equals("cheese")) {pizza = new NYStyleCheesePizza();} else if (type.equals("veggie")) {pizza = new NYStyleVeggiePizza();} } else if (style.equals("Chicago")) {if (type.equals("cheese")) {pizza = new ChicagoStyleCheesePizza();} else if (type.equals("veggie")) {pizza = new ChicagoStyleVeggiePizza();}} else {System.out.println("Error: invalid type of pizza");return null;}pizza.prepare();pizza.bake();pizza.cut();pizza.box();return pizza;}}

2 简单工厂产生具体披萨披萨店调用工厂做出具体披萨

简单工厂其实不是一个设计模式，更像是一种变成习惯

// 普通做法相比只是将做披萨封装出去，有工厂提供。public class SimplePizzaFactory {public Pizza createPizza(String type) {// type 类型即代表披萨店区域，又代表披萨的种类。两个维度这样不好Pizza pizza = null;if (type.equals("NYcheese")) {pizza = new NYCheesePizza();} else if (type.equals("NYveggie")) {pizza = new NYVeggiePizza();}else if (type.equals("Chicagocheese")) {pizza = new ChicagoCheesePizza();} else if (type.equals("Chicagoveggie")) {pizza = new ChicagoVeggiePizza();}return pizza;}}public class PizzaStore {SimplePizzaFactory factory;public PizzaStore(SimplePizzaFactory factory) { this.factory = factory;}public Pizza orderPizza(String type) {Pizza pizza = factory.createPizza(type);pizza.prepare();pizza.bake();pizza.cut();pizza.box();return pizza;}}

3 工厂方法模式

// 把做什么风味的决定权交给披萨店（PizzaStore）把做披萨还得限制于具体PizzaStore类中public abstract class PizzaStore {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;}// 由子披萨店，即各地区披萨店自主决定（pizzaStore的类型）披萨风味和披萨种类（type）abstract Pizza createPizza(String type);}public class NYPizzaStore extends PizzaStore {Pizza createPizza(String item) {// 另外，靠字符串匹配，出错几率大些，可用代表参数类型的对象，静态变量、枚举代替if (item.equals("cheese")) {return new NYStyleCheesePizza();} else if (item.equals("veggie")) {return new NYStyleVeggiePizza();} else return null;}}public class ChicagoPizzaStore extends PizzaStore {Pizza createPizza(String item) {if (item.equals("cheese")) {return new ChicagoStyleCheesePizza();} else if (item.equals("veggie")) {return new ChicagoStyleVeggiePizza();} else return null;}}// 测试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("veggie");System.out.println("Ethan ordered a " + pizza.getName() + "\n");pizza = chicagoStore.orderPizza("veggie");System.out.println("Joel ordered a " + pizza.getName() + "\n");}}// 公共代码public abstract class Pizza {//原料下边会有对原料的变体String name;String dough;String sauce;String veggie;String clam;String perpersoni;ArrayList<String> toppings = new ArrayList<String>();void prepare() {// 对基本披萨的处理System.out.println("Prepare " + name);System.out.println("Tossing dough...");System.out.println("Adding sauce...");System.out.println("Adding toppings: ");for (String topping : toppings) {System.out.println(" " + topping);}}void bake() {System.out.println("Bake for 25 minutes at 350");}void cut() {System.out.println("Cut 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 (String topping : toppings) {display.append(topping + "\n");}return display.toString();}}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");}}public class NYStyleCheesePizza extends Pizza {public NYStyleCheesePizza() { name = "NY Style Sauce and Cheese Pizza";dough = "Thin Crust Dough";sauce = "Marinara Sauce";toppings.add("Grated Reggiano Cheese");}}

简单工厂与工厂方法的区别

简单工厂把全部工作在一个地方都处理完了；它把创建产品的代码封装起来，但不具备工厂方法的弹性，因为简单工厂不能变更正在创建的产品

抽象工厂方法却是创建一个框架，让子类决定如何实现，即子类决定产品类型

需求2 保证风味种类或者说原料都得是指定的

用对象来限定种类

4 抽象工厂模式

//定义产生产品家族的接口-抽象工厂public interface PizzaIngredientFactory {//每种原料就是一种类public Dough createDough();public Sause createSause();public Cheese createCheese ();}// 具体工厂决定具体的产品public NYPizzaIngredientFactory implements PizzaIngredientFactory {public Dough createDough(){return ThinCrustDoough();}public Sause createSause(){return MarinaraSause();}}// 给披萨加上配料public abstract class Pizza{public Dough dough;public Sause sause;public Veggies veggies[];public Cheese cheese;public Peppersoni perppersoni;public Clams clams;abstract void prepare();// 声明称抽象，从原料工厂中获取pizza所需的具体风味原料void bake() {System.out.println("Bake for 25 minutes at 350");}void cut() {System.out.println("Cut 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 (String topping : toppings) {display.append(topping + "\n");}return display.toString();}}//具体类型的披萨public ChessPizza extends Pizza{PizzaIngredientFactory pizzaIngredientFactory; // 盛放具体类型的原料工厂public ChessPizza(PizzaIngredientFactory pizzaIngredientFactory){this.pizzaIngredientFactory = pizzaIngredientFactory;}@Overridepublic void prepare(){this.dough = pizzaIngredientFactory.getDough();this.sause= pizzaIngredientFactory.getSause();}}public Veggiesizza extends Pizza{PizzaIngredientFactory pizzaIngredientFactory; // 盛放具体类型的原料工厂public ChessPizza(PizzaIngredientFactory pizzaIngredientFactory){this.pizzaIngredientFactory = pizzaIngredientFactory;}@Overridepublic void prepare(){// 具体风味的不同，及配料的不同this.dough = pizzaIngredientFactory.getDough();this.sause= pizzaIngredientFactory.getSause();this.veggies= pizzaIngredientFactory.getVeggies();}}//纽约地区的披萨店public NYPizzaStore extends PizzaStore {Pizza pizza = null;PizzaIngredientFactory pizzaIngredientFactory = new NYPizzaIngredientFactory();//NYPizzaIngredientFactory是NYPizzaStore披萨店的配料@Overridepublic Pizza createPizza(String type){if("cheese".equals(type)){ pizza = new CheesePizza(pizzaIngredientFactory);}if("veggie".equals(type)){pizza = new Veggiesizza(pizzaIngredientFactory);}}} //测试public orderPizzaTest{main(String[] args){//由子类决定store 以及风味（配料）的类型PizzaStore nyStore = new NYPizzaStore();PizzaIngredientFactory nyPizzaIngredientFactory = new NYPizzaIngredientFactory();Pizza chessPizza = nyStore.orderPizza("cheese"); //完成了下边的工作 - //一旦确定了PizzaStore的类型，也就确定了原料工厂类型；设置"cheese"类型时，把原料工厂类型设置给了chessPizza;- // Pizza chessPizza = createPissa("cheese"); 完成了基本的创建- // chessPizza = chessPizza.prepare()//pizza的具体类型调用后续处理，将原料设置给了基本的披萨}}