創(chuàng)建型設(shè)計模式 培訓(xùn)英文

1、Bryan Li6/18/2007,?,Agenda,OO Design PrincipleOCP(Open-Closed Principle)LSP(Liskov Substitution Principle)SRP(single responsibility Principle)DIP(Dependence Inversion Principle)ISP(Interface Segregation Principle)

2、CARP(Composite/Aggregate Reuse Principle)LoD(Las od Demeter—Least Knowledge Principle-LKP)Design PatternCreational PatternStructural PatternBehavioral Pattern,Agenda,Creational PatternFactory PatternSimple Factory

3、Factory MethodAbstract Factory,Factory Pattern,Simple FactorySimply moved the code that is used to create object to a new class Creator.,Factory Pattern,Pizza StoryYou want to open a pizza store, Assume that you orga

4、nize like this:,Simple Pattern,public class PizzaStore {Pizza orderPizza(String type) {Pizza pizza = null;if(type.equals("chees")) {pizza = new CheesePizza();} else if (type.equals("greek")) {pi

5、zza = new GreekPizza();} else if (type.equals("pepperoni")) {pizza = new PepperoniPizza();}pizza.prepare();pizza.bake();pizza.cut();pizza.box();return pizza;}},Simple Pattern,Mending design of pizza s

6、tory,Simple Pattern,Add SimplePizzaFactory Classpublic class SimplePizzaFactory {public static Pizza createPizza(String type) {Pizza pizza = null;if (type.equals("chees")) {pizza = new CheesePizza();} els

7、e if (type.equals("greek")) {pizza = new GreekPizza();} else if (type.equals("pepperoni")) {pizza = new PepperoniPizza();}return pizza;}},public class PizzaStore {SimplePizzaFactory factory;p

8、ublic Pizza orderPizza(String type) {Pizza pizza = SimplePizzaFactory.createPizza(type);pizza.prepare();pizza.bake();pizza.cut();pizza.box();return pizza;}},Simple Pattern,Featureyou don't need to instantiat

9、e an object to make use of the create method you can't create sublcass and change the behavior of the create methodNot typical design pattern-- more of a programming idiomFade FormatMerge Creator into ConcretePro

10、duct,Simple Pattern,AdvantageReuse the code that create objectDisadvantageIf product has any change, Creator class should be impacted.OO Design PrincipleOCP: if add new type of product, in the view of client and pro

11、duct, it conform to OCP, but in the view of Factory Creator, it does not.,Factory Method,Define an interface for creating an object, but lets subclasses decide which class to instantiate. Factory Method lets a class defe

12、r instantiation to subclasses.,Factory Method,Pizza StoryBecause your pizza store has a good business, many people want to open your sub store in New York and Chicago. So you will the localize favor problem.Based on si

13、mple factory, design like the following:,Factory Method,The above design's IssueBecause simpele factory generally use static create method. So if there are several simple factory creators, it will impact encapsulati

14、on of client class, that is PizzaStore.public class PizzaStore {SimplePizzaFactory factory;public Pizza orderPizza(String type) {Pizza pizza = SimplePizzaFactory.createPizza(type); // or NYPizzaFactory.createPizza(

15、type); // or ChicagoPizzaFactory.createPizza(type);pizza.prepare();pizza.bake();pizza.cut();pizza.box();return pizza; } },Factory Method,The above design's Issueif simpele factory generally use non-static cre

16、ate method and other factories derive from simplePizzaFactory. So What?,Factory Method,public class PizzaStore {SimplePizzaFactory factory;public PizzaStore(SimplePizzaFactory factory) {this.factory = factory;}publi

17、c Pizza orderPizza(String type) {Pizza pizza = factory.createPizza(type);pizza.prepare();pizza.bake();pizza.cut();pizza.box();return pizza;} }public class Client {public static void main(String[] args) {NYPizza

18、Factory nyfactory = new NYPizzaFactory();PizzaStore nyStore = new PizzaStore(nyfactory);nyStore.orderPizza("Veggie");} },Factory Method,New requirement bring new issueNow New York pizza store's procedur

19、e of make pizza was changed: they'd bake things a little differently, they needn't cut the pizza and they'd use third-party boxes. So we must have different pizza store class in order to solve this issue.,Add

20、 subclass,Factory Method,Refactor the designNow the hierarchy of Pizzastore completely shows the hierarchy of simple factory. So now the series of factory class are redundancy. We should move the method of factory into

21、the series classes of Pizzastore. The refactored design is as the below:,Client,Factory Method,Product,Factory Method,public abstract class PizzaStore {public Pizza orderPizza(String type) {Pizza pizza = createPizza(ty

22、pe);doHandlePizza(pizza);return pizza;}protected void doHandlePizza(Pizza pizza) {pizza.prepare();pizza.bake();pizza.cut();pizza.box();}public abstract Pizza createPizza(String type);},Factory Method,public cl

23、ass NYStylePizzaStore extends PizzaStore {public Pizza createPizza(String type) {Pizza pizza = null;if (type.equals("chees")) {pizza = new NYStyleCheesePizza();} else if (type.equals("greek")) {

24、pizza = new NYStyleGreekPizza();} else if (type.equals("pepperoni")) {pizza = new NYStylePepperoniPizza();}return pizza;}protected void doHandlePizza(Pizza pizza) {pizza.prepare();pizza.bake();//pizza.

25、cut();pizza.box();} },Factory Method,public class ChicagoStylePizzaStore extends PizzaStore {public Pizza createPizza(String type) {Pizza pizza = null;if (type.equals("chees")) {pizza = new ChicagoStyleC

26、heesePizza();} else if (type.equals("greek")) {pizza = new ChicagoStyleGreekPizza();} else if (type.equals("pepperoni")) {pizza = new ChicagoStylePepperoniPizza();}return pizza;}},Factory Meth

27、od,FeatureThe Factory Method lets subclasses decide which class to instantiate.A factory method may be parameterized(or not) to select among several variations of a product.FM doesn't certainly return new object v

28、ery time. But returned object must be created by FM itself, but not be passed from outside.Returned type should be abstract type, not concrete type.,Factory Method,Advantagethe creator/client class is written without k

29、nowledge of the actual products that will be created; that is clients decoupled from the concret types.DisadvantageClients might have to subclass the Creator class just to create a particular ConcreteProduct object.Wi

30、th OO Design PrincipleOCP: in the view of client/creator, it conform to OCP, but in the view of product, not certainly. In general, in FMP, there is a only kind of product. If there are several kinds, need parameterized

31、 create method like createPizza method. So if add product kind, all client/creator will be impacted. So not obey OCP.,Abstract Factory,Provide an interface for creating families of related or dependent objects without sp

32、ecifying their concrete classes.,Abstract Factory,Pizza storyPizza from different place has different ingredients,,PlumTomatoSauce,ThickCrustDough,MozzarellaCheese,FrozenPepperoni,New York,,MarinaraSauce,ThinCrustDough,

33、ReggianoCheese,FreshPepperoni,Chicago,Abstract Factory,,Close coupling,Over-deep hierarchy,Abstract Factory,Pizza story – part of class diagram,Abstract Factory,public interface Pizza {void prepare();void bake();void

34、cut();void box();}public abstract class PepperoniPizza implements Pizza {protected Dough dough;protected Sauce sauce;protected Cheese cheese;protected Pepperoni pepperoni;public abstract void prepare();public vo

35、id box() { System.out.println("box pepperoni pizza."); }public void bake() { System.out.println("bake pepperoni pizza."); }public void cut() {System.out.println("cut pepperoni pizza."); }

36、},Abstract Factory,public class NYStylePepperoniPizza extends PepperoniPizza {public void prepare() {dough = new ThickCrustDough();sauce = new PlumTomatoSauce();cheese = new MozzarellaCheese();pepperoni = new Frozen

37、Pepperoni();}}public class NYStyleCheesePizza extends CheesePizza {public void prepare() {dough = new ThickCrustDough();sauce = new PlumTomatoSauce();cheese = new MozzarellaCheese();}},public class NYPizzaIngred

38、ientFactory {public Dough createDough() {return new ThickCrustDough(); }public Sauce createSauce() {return new PlumTomatoSauce(); }public Cheese createCheese() {return new MozzarellaCheese(); }public Pepperoni cre

39、atePepperoni() {return new FrozenPepperoni(); }},,,Abstract Factory,Use refactor “extract interface” to get PizzaIngredientFactory interface in NYPizzaIngredientFactory class.public interface PizzaIngredientFactory {

40、public abstract Dough createDough();public abstract Sauce createSauce();public abstract Cheese createCheese();public abstract Pepperoni createPepperoni();}public class NYPizzaIngredientFactory implements PizzaIngr

41、edientFactory{...},public class NYPizzaIngredientFactory {public Dough createDough() {return new ThickCrustDough(); }public Sauce createSauce() {return new PlumTomatoSauce(); }public Cheese createCheese() {return

42、 new MozzarellaCheese(); }public Pepperoni createPepperoni() {return new FrozenPepperoni(); }},Abstract Factory,public class ChicagoStyleCheesePizza extends CheesePizza {public void prepare() {dough = new ThinCrustD

43、ough();sauce = new MarinaraSauce();cheese = new ReggianoCheese();}}public class NYStyleCheesePizza extends CheesePizza {public void prepare() {dough = new ThickCrustDough();sauce = new PlumTomatoSauce();cheese

44、= new MozzarellaCheese();}},public class ChicagoStyleCheesePizza extends CheesePizza {PizzaIngredientFactory factory;public ChicagoStyleCheesePizza() {factory = new ChicagoPizzaIngredientFactory(); }public void pre

45、pare() {dough = factory.createDough();sauce = factory.createSauce();cheese = factory.createCheese(); } }public class NYStyleCheesePizza extends CheesePizza {PizzaIngredientFactory factory;public NYStyleCheesePizza

46、() {factory = new NYPizzaIngredientFactory(); }public void prepare() {dough = factory.createDough();sauce = factory.createSauce();cheese = factory.createCheese();} },,,Abstract Factory,Use refactor “pull up” to rest

47、ract factory property and prepare method into cheesePizza. And then we can delete ChicagoStyleCheesePizza and NYStyleCheesePizza because combination of CheesePizza and series of IngredientFactory will get these two favor

48、s pizza. In the same way, we can delete ChicagoStylePepperoniPizza and NYStylePepperoniPizza.public abstract class CheesePizza implements Pizza {protected Dough dough;protected Sauce sauce;protected Cheese cheese;pr

49、otected PizzaIngredientFactory factory;public CheesePizza(PizzaIngredientFactory factory) { this.factory = factory; }public void prepare() {dough = factory.createDough();sauce = factory.createSauce();cheese = factor

50、y.createCheese(); } }public void box() { } public void bake() { } public void cut() { }},Abstract Factory,,Abstract Factory,Product,Client,Client,Abstract Factory,FeatureProvides an interface for a family of product

51、s.Create Instance through Composition/ Aggregation.Doesn't certainly return new object very time. But returned object must be created by AF itself, but not be passed from outside.Returned type should be abstract t

52、ype, not concrete type.,AdvantageClients are decoupled from the actual concrete products they use.Adding new family of product is easyDisadvantageAdding new kind of product is difficult.With OO Design PrincipleOCP:

53、 in the view of Adding new family of product, it conform to OCP, but in the view of Adding new kind of product, it doesn't.CARP: that client create product through factory conform to CARP,FMP vs. AFP,CommonCreate P

54、roduct. Furthmore, client know nothing about knowledge of concrete product.DifferenceFMP is for one kind of product, AFP is for several kinds of product. Q: Right? A: Wrong!!! so it's not differenceFMP create prod