Open Mvitimin opened 7 months ago
클래스 확장에는 열려 있어야 하지만 변경에는 닫혀 있어야 한다.
스타벅스 시스템을 생각해보자 휘핑크림 추가 샷추가 이러한 부속 첨가물을 어떻게 구현할 수 있을까? 예를들어 어떤 고객이 모카와 휘핑크림을 추가한 다크 로스트 커피를 주문한다면 어떻게 가격을 계산할까?
1.DarkRoast 객체를 가져온다. 2.Mocha 객체로 장식한다. 3.Whip 객체로 장식한다. 4.cost() 메소드를 호출한다. 이때 첨가물의 가격을 계산하는 일은 객체에게 위임한다.
즉, Whip, Mocha, DarkRoast모두 cost 라는 메소드를 가지고있어서 각각 cost를 호출해야한다.
public abstract class Beverage {
String description = "Unknown Beverage";
public String getDescription() {
return description;
}
public abstract double cost();
}
public abstract class CondimentDecorator extends Beverage {
Beverage beverage;
public abstract String getDescription();
}
public class DarkRoast extends Beverage {
public DarkRoast() {
description = "Dark Roast Coffee";
}
public double cost() {
return .99;
}
}
public class Decaf extends Beverage {
public Decaf() {
description = "Decaf Coffee";
}
public double cost() {
return 1.05;
}
}
public class Milk extends CondimentDecorator {
public Milk(Beverage beverage) {
this.beverage = beverage;
}
public String getDescription() {
return beverage.getDescription() + ", Milk";
}
public double cost() {
return .10 + beverage.cost();
}
}
public class Mocha extends CondimentDecorator {
public Mocha(Beverage beverage) {
this.beverage = beverage;
}
public String getDescription() {
return beverage.getDescription() + ", Mocha";
}
public double cost() {
return .20 + beverage.cost();
}
}
public class StarbuzzCoffee {
public static void main(String args[]) {
Beverage beverage = new Espresso();
System.out.println(beverage.getDescription()
+ " $" + beverage.cost());
Beverage beverage2 = new DarkRoast();
beverage2 = new Mocha(beverage2);
beverage2 = new Mocha(beverage2);
beverage2 = new Whip(beverage2);
System.out.println(beverage2.getDescription()
+ " $" + beverage2.cost());
Beverage beverage3 = new HouseBlend();
beverage3 = new Soy(beverage3);
beverage3 = new Mocha(beverage3);
beverage3 = new Whip(beverage3);
System.out.println(beverage3.getDescription()
+ " $" + beverage3.cost());
}
}
팩토리 메소드 패턴에서는 객체를 생성할 때 필요한 인터페이스를 만듭니다. 어떤 클래스의 인스턴스를 만들지는 서브클래스에서 결정합니다. 팩토리 메소드 패턴을 사용하면 클래스 인스턴스 만드는일을 서브클래스에게 맡기게 됩니다.
public abstract class Pizza {
String name;
String dough;
String sauce;
ArrayList<String> toppings = new ArrayList<String>();
void prepare() {
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 NYStyleCheesePizza extends Pizza {
public NYStyleCheesePizza() {
name = "NY Style Sauce and Cheese Pizza";
dough = "Thin Crust Dough";
sauce = "Marinara Sauce";
toppings.add("Grated Reggiano Cheese");
}
}
public class NYStylePepperoniPizza extends Pizza {
public NYStylePepperoniPizza() {
name = "NY Style Pepperoni Pizza";
dough = "Thin Crust Dough";
sauce = "Marinara Sauce";
toppings.add("Grated Reggiano Cheese");
toppings.add("Sliced Pepperoni");
toppings.add("Garlic");
toppings.add("Onion");
toppings.add("Mushrooms");
toppings.add("Red Pepper");
}
}
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;
}
}
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;
}
}
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 if (item.equals("clam")) {
return new ChicagoStyleClamPizza();
} else if (item.equals("pepperoni")) {
return new ChicagoStylePepperoniPizza();
} else return null;
}
}
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 (type.equals("clam")) {
pizza = new NYStyleClamPizza();
} else if (type.equals("pepperoni")) {
pizza = new NYStylePepperoniPizza();
}
} else if (style.equals("Chicago")) {
if (type.equals("cheese")) {
pizza = new ChicagoStyleCheesePizza();
} else if (type.equals("veggie")) {
pizza = new ChicagoStyleVeggiePizza();
} else if (type.equals("clam")) {
pizza = new ChicagoStyleClamPizza();
} else if (type.equals("pepperoni")) {
pizza = new ChicagoStylePepperoniPizza();
}
} else {
System.out.println("Error: invalid type of pizza");
return null;
}
pizza.prepare();
pizza.bake();
pizza.cut();
pizza.box();
return pizza;
}
}
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");
}
}
public interface PizzaIngredientFactory {
public Dough createDough();
public Sauce createSauce();
public Cheese createCheese();
public Veggies[] createVeggies();
public Pepperoni createPepperoni();
public Clams createClam();
}
public class ChicagoPizzaIngredientFactory
implements PizzaIngredientFactory
{
public Dough createDough() {
return new ThickCrustDough();
}
public Sauce createSauce() {
return new PlumTomatoSauce();
}
public Cheese createCheese() {
return new MozzarellaCheese();
}
public Veggies[] createVeggies() {
Veggies veggies[] = { new BlackOlives(),
new Spinach(),
new Eggplant() };
return veggies;
}
public Pepperoni createPepperoni() {
return new SlicedPepperoni();
}
public Clams createClam() {
return new FrozenClams();
}
}
public class NYPizzaIngredientFactory implements PizzaIngredientFactory {
public Dough createDough() {
return new ThinCrustDough();
}
public Sauce createSauce() {
return new MarinaraSauce();
}
public Cheese createCheese() {
return new ReggianoCheese();
}
public Veggies[] createVeggies() {
Veggies veggies[] = { new Garlic(), new Onion(), new Mushroom(), new RedPepper() };
return veggies;
}
public Pepperoni createPepperoni() {
return new SlicedPepperoni();
}
public Clams createClam() {
return new FreshClams();
}
}
public abstract class Pizza {
String name;
Dough dough;
Sauce sauce;
Veggies veggies[];
Cheese cheese;
Pepperoni pepperoni;
Clams clam;
abstract void prepare();
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");
}
void setName(String name) {
this.name = name;
}
String getName() {
return name;
}
public String toString() {
StringBuffer result = new StringBuffer();
result.append("---- " + name + " ----\n");
if (dough != null) {
result.append(dough);
result.append("\n");
}
if (sauce != null) {
result.append(sauce);
result.append("\n");
}
if (cheese != null) {
result.append(cheese);
result.append("\n");
}
if (veggies != null) {
for (int i = 0; i < veggies.length; i++) {
result.append(veggies[i]);
if (i < veggies.length-1) {
result.append(", ");
}
}
result.append("\n");
}
if (clam != null) {
result.append(clam);
result.append("\n");
}
if (pepperoni != null) {
result.append(pepperoni);
result.append("\n");
}
return result.toString();
}
}
public class CheesePizza extends Pizza {
PizzaIngredientFactory ingredientFactory;
public CheesePizza(PizzaIngredientFactory ingredientFactory) {
this.ingredientFactory = ingredientFactory;
}
void prepare() {
System.out.println("Preparing " + name);
dough = ingredientFactory.createDough();
sauce = ingredientFactory.createSauce();
cheese = ingredientFactory.createCheese();
}
}
public abstract class PizzaStore {
protected 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;
}
}
public class NYPizzaStore extends PizzaStore {
protected Pizza createPizza(String item) {
Pizza pizza = null;
PizzaIngredientFactory ingredientFactory =
new NYPizzaIngredientFactory();
if (item.equals("cheese")) {
pizza = new CheesePizza(ingredientFactory);
pizza.setName("New York Style Cheese Pizza");
} else if (item.equals("veggie")) {
pizza = new VeggiePizza(ingredientFactory);
pizza.setName("New York Style Veggie Pizza");
} else if (item.equals("clam")) {
pizza = new ClamPizza(ingredientFactory);
pizza.setName("New York Style Clam Pizza");
} else if (item.equals("pepperoni")) {
pizza = new PepperoniPizza(ingredientFactory);
pizza.setName("New York Style Pepperoni Pizza");
}
return pizza;
}
}
추상화된 것에 의존하게 만들고 구상 클래스에 의존하지 않게 만든다.
고수준의 구성요소가 저수준의 구성 요소에 의존하면 안되며, 항상 추상화에 의존하게 만들어야한다.
https://en.wikipedia.org/wiki/Initialization-on-demand_holder_idiom
public class Something {
private Something() {}
private static class LazyHolder {
static final Something INSTANCE = new Something();
}
public static Something getInstance() {
return LazyHolder.INSTANCE;
}
}
요청 내역을 객체로 캡슐화해서 객체를 서로 다른 요청 내역에 따라 매개변수화 할 수 있다. 이러한 요청을 큐에 저장하거나 로그로 기록하거나 작업 취소 기능을 사용할 수 있다.
인보커 로딩
식당 | 커맨드 패턴 |
---|---|
종업원 | 인보커 객체 |
주방장 | 리시버 객체 |
orderUp | execute() |
주문서 | 커맨드 객체 |
고객 | 클라이언트 객체 |
takeOrder | setCommand |
public interface Command {
public void execute();
}
public class Light {
public Light() {
}
public void on() {
System.out.println("Light is on");
}
public void off() {
System.out.println("Light is off");
}
}
public class LightOnCommand implements Command {
Light light;
public LightOnCommand(Light light) {
this.light = light;
}
public void execute() {
light.on();
}
}
//
// This is the invoker
//
public class SimpleRemoteControl {
Command slot;
public SimpleRemoteControl() {}
public void setCommand(Command command) {
slot = command;
}
public void buttonWasPressed() {
slot.execute();
}
}
public static void main(String[] args) { // 클라이언트
SimpleRemoteControl remote = new SimpleRemoteControl(); // remote 변수가 invoker 역할
Light light = new Light(); // Receiver light 객체
GarageDoor garageDoor = new GarageDoor();
LightOnCommand lightOn = new LightOnCommand(light); // Command 객체 receiver 전달
GarageDoorOpenCommand garageOpen =
new GarageDoorOpenCommand(garageDoor);
remote.setCommand(lightOn); // Command 객체 인보커에게 전달
remote.buttonWasPressed();
remote.setCommand(garageOpen);
remote.buttonWasPressed();
}
public class Light {
String location = "";
public Light(String location) {
this.location = location;
}
public void on() {
System.out.println(location + " light is on");
}
public void off() {
System.out.println(location + " light is off");
}
}
public class LightOffCommand implements Command {
Light light;
public LightOffCommand(Light light) {
this.light = light;
}
public void execute() {
light.off();
}
}
public class StereoOnWithCDCommand implements Command {
Stereo stereo;
public StereoOnWithCDCommand(Stereo stereo) {
this.stereo = stereo;
}
public void execute() {
stereo.on();
stereo.setCD();
stereo.setVolume(11);
}
}
public class RemoteLoader {
public static void main(String[] args) {
RemoteControl remoteControl = new RemoteControl();
Light livingRoomLight = new Light("Living Room");
Light kitchenLight = new Light("Kitchen");
CeilingFan ceilingFan= new CeilingFan("Living Room");
GarageDoor garageDoor = new GarageDoor("Garage");
Stereo stereo = new Stereo("Living Room");
LightOnCommand livingRoomLightOn =
new LightOnCommand(livingRoomLight);
LightOffCommand livingRoomLightOff =
new LightOffCommand(livingRoomLight);
LightOnCommand kitchenLightOn =
new LightOnCommand(kitchenLight);
LightOffCommand kitchenLightOff =
new LightOffCommand(kitchenLight);
CeilingFanOnCommand ceilingFanOn =
new CeilingFanOnCommand(ceilingFan);
CeilingFanOffCommand ceilingFanOff =
new CeilingFanOffCommand(ceilingFan);
GarageDoorUpCommand garageDoorUp =
new GarageDoorUpCommand(garageDoor);
GarageDoorDownCommand garageDoorDown =
new GarageDoorDownCommand(garageDoor);
StereoOnWithCDCommand stereoOnWithCD =
new StereoOnWithCDCommand(stereo);
StereoOffCommand stereoOff =
new StereoOffCommand(stereo);
remoteControl.setCommand(0, livingRoomLightOn, livingRoomLightOff);
remoteControl.setCommand(1, kitchenLightOn, kitchenLightOff);
remoteControl.setCommand(2, ceilingFanOn, ceilingFanOff);
remoteControl.setCommand(3, stereoOnWithCD, stereoOff);
System.out.println(remoteControl);
remoteControl.onButtonWasPushed(0);
remoteControl.offButtonWasPushed(0);
remoteControl.onButtonWasPushed(1);
remoteControl.offButtonWasPushed(1);
remoteControl.onButtonWasPushed(2);
remoteControl.offButtonWasPushed(2);
remoteControl.onButtonWasPushed(3);
remoteControl.offButtonWasPushed(3);
}
}
//
// This is the invoker
//
public class RemoteControl {
Command[] onCommands;
Command[] offCommands;
public RemoteControl() {
onCommands = new Command[7];
offCommands = new Command[7];
Command noCommand = new NoCommand();
for (int i = 0; i < 7; i++) {
onCommands[i] = noCommand;
offCommands[i] = noCommand;
}
}
public void setCommand(int slot, Command onCommand, Command offCommand) {
onCommands[slot] = onCommand;
offCommands[slot] = offCommand;
}
public void onButtonWasPushed(int slot) {
onCommands[slot].execute();
}
public void offButtonWasPushed(int slot) {
offCommands[slot].execute();
}
public String toString() {
StringBuffer stringBuff = new StringBuffer();
stringBuff.append("\n------ Remote Control -------\n");
for (int i = 0; i < onCommands.length; i++) {
stringBuff.append("[slot " + i + "] " + onCommands[i].getClass().getName()
+ " " + offCommands[i].getClass().getName() + "\n");
}
return stringBuff.toString();
}
}
특정 클래스 인터페이스를 클라이언트에서 요구하는 다른 인터페이스로 변환한다. 인터페이스가 호환되지 않아 같이 쓸수 없었던 클래스를 사용할 수 있게 도와준다.
public interface Duck {
public void quack();
public void fly();
}
public interface Turkey {
public void gobble();
public void fly();
}
public class DuckAdapter implements Turkey {
Duck duck;
Random rand;
public DuckAdapter(Duck duck) {
this.duck = duck;
rand = new Random();
}
public void gobble() {
duck.quack();
}
public void fly() {
if (rand.nextInt(5) == 0) {
duck.fly();
}
}
}
public class TurkeyAdapter implements Duck {
Turkey turkey;
public TurkeyAdapter(Turkey turkey) {
this.turkey = turkey;
}
public void quack() {
turkey.gobble();
}
public void fly() {
for(int i=0; i < 5; i++) {
turkey.fly();
}
}
}
public class TurkeyTestDrive {
public static void main(String[] args) {
MallardDuck duck = new MallardDuck();
Turkey duckAdapter = new DuckAdapter(duck);
for(int i=0;i<10;i++) {
System.out.println("The DuckAdapter says...");
duckAdapter.gobble();
duckAdapter.fly();
}
}
}
퍼사드는 인터페이스를 단순하게 만드는 용도로 쓰이는 반면 어댑터는 인터페이스를 다른 인터페이스로 변환하는 용도로 쓰인다. 데코레이터는 객체를 감싸서 새로운 행동을 추가하는 용도이다.
패턴 | 용도 |
---|---|
데코레이터 | 인터페이스는 바꾸지 않고 책임만 추가 |
어댑터 | 하나의 인터페이스를 다른 인터페이스로 변환 |
퍼사드 | 인터페이스를 간단하게 변경 |
public class HomeTheaterFacade {
Amplifier amp;
Tuner tuner;
StreamingPlayer player;
CdPlayer cd;
Projector projector;
TheaterLights lights;
Screen screen;
PopcornPopper popper;
public HomeTheaterFacade(Amplifier amp,
Tuner tuner,
StreamingPlayer player,
Projector projector,
Screen screen,
TheaterLights lights,
PopcornPopper popper) {
this.amp = amp;
this.tuner = tuner;
this.player = player;
this.projector = projector;
this.screen = screen;
this.lights = lights;
this.popper = popper;
}
public void watchMovie(String movie) {
System.out.println("Get ready to watch a movie...");
popper.on();
popper.pop();
lights.dim(10);
screen.down();
projector.on();
projector.wideScreenMode();
amp.on();
amp.setStreamingPlayer(player);
amp.setSurroundSound();
amp.setVolume(5);
player.on();
player.play(movie);
}
public void endMovie() {
System.out.println("Shutting movie theater down...");
popper.off();
lights.on();
screen.up();
projector.off();
amp.off();
player.stop();
player.off();
}
public void listenToRadio(double frequency) {
System.out.println("Tuning in the airwaves...");
tuner.on();
tuner.setFrequency(frequency);
amp.on();
amp.setVolume(5);
amp.setTuner(tuner);
}
public void endRadio() {
System.out.println("Shutting down the tuner...");
tuner.off();
amp.off();
}
}
public float getTemp() {
Thermometer thermometer = station.getThermometer();
return thermometer.getTemperature(); // 원칙에 어긋남
}
public float getTemp() {
return station.getTemperature(); // 원칙을 따름
}
디미터 법칙(Law of Demeter)은 데메테르 법칙이라고도 불리며 줄여서 LoD라고도 불립니다. 이 법칙은 "최소한의 지식 원칙(The Principle of Least Knowledge)으로 알려져 있으며, 모듈은 자신이 조작하는 객체의 속사정을 몰라야 한다는 것을 의미합니다.
각각의 서브클래스를 일일이 열어서 여러군데를 고치기 보다, CaffeineBeverage 클래스에 알고리즘 지식이 집중되어 있으며 일부 구현만 서브클래스에 의존합니다.
public abstract class CaffeineBeverage {
final void prepareRecipe() {
boilWater();
brew();
pourInCup();
addCondiments();
}
abstract void brew();
abstract void addCondiments();
void boilWater() {
System.out.println("Boiling water");
}
void pourInCup() {
System.out.println("Pouring into cup");
}
}
public class Coffee extends CaffeineBeverage {
public void brew() {
System.out.println("Dripping Coffee through filter");
}
public void addCondiments() {
System.out.println("Adding Sugar and Milk");
}
}
public class Tea extends CaffeineBeverage {
public void brew() {
System.out.println("Steeping the tea");
}
public void addCondiments() {
System.out.println("Adding Lemon");
}
}
public class BeverageTestDrive {
public static void main(String[] args) {
Tea tea = new Tea();
Coffee coffee = new Coffee();
System.out.println("\nMaking tea...");
tea.prepareRecipe();
System.out.println("\nMaking coffee...");
coffee.prepareRecipe();
TeaWithHook teaHook = new TeaWithHook();
CoffeeWithHook coffeeHook = new CoffeeWithHook();
System.out.println("\nMaking tea...");
teaHook.prepareRecipe();
System.out.println("\nMaking coffee...");
coffeeHook.prepareRecipe();
}
}
Hook는 추상 클래스에서 선언되지만 기본적인 내용만 구현되어있거나 아무 코드도 들어있지 않은 메소드.
public abstract class CaffeineBeverageWithHook {
final void prepareRecipe() {
boilWater();
brew();
pourInCup();
if (customerWantsCondiments()) {
addCondiments();
}
}
abstract void brew();
abstract void addCondiments();
void boilWater() {
System.out.println("Boiling water");
}
void pourInCup() {
System.out.println("Pouring into cup");
}
// 별 내용이 없는 기본 메소드 구현, 서브클래스에서 필요할 때 오버라이드 할 수 있는 메소드 이므로 후크이다.
boolean customerWantsCondiments() {
return true;
}
}
public class CoffeeWithHook extends CaffeineBeverageWithHook {
public void brew() {
System.out.println("Dripping Coffee through filter");
}
public void addCondiments() {
System.out.println("Adding Sugar and Milk");
}
// 후크를 오버라이드해서 원하는 기능을 얻음
public boolean customerWantsCondiments() {
String answer = getUserInput();
if (answer.toLowerCase().startsWith("y")) {
return true;
} else {
return false;
}
}
private String getUserInput() {
String answer = null;
System.out.print("Would you like milk and sugar with your coffee (y/n)? ");
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
try {
answer = in.readLine();
} catch (IOException ioe) {
System.err.println("IO error trying to read your answer");
}
if (answer == null) {
return "no";
}
return answer;
}
}
public class BeverageTestDrive {
public static void main(String[] args) {
Tea tea = new Tea();
Coffee coffee = new Coffee();
System.out.println("\nMaking tea...");
tea.prepareRecipe();
System.out.println("\nMaking coffee...");
coffee.prepareRecipe();
TeaWithHook teaHook = new TeaWithHook();
CoffeeWithHook coffeeHook = new CoffeeWithHook();
System.out.println("\nMaking tea...");
teaHook.prepareRecipe();
System.out.println("\nMaking coffee...");
coffeeHook.prepareRecipe();
}
}
패턴 | 설명 |
---|---|
템플릿 메소드 패턴 | 알고르짐의 어떤 단계를 구현하는 방법을 서브클래스에서 결정한다. |
전략 패턴 | 바꿔 쓸 수 있는 행동을 캡슐화하고, 어떤 행동을 사용할지는 서브클래스에게 맡긴다. |
팩토리 메소드 패턴 | 구상 클래스의 인스턴스 생성을 서브 클래스에서 결정한다. |
컬렉션의 구현 방법을 노출하지 않으면서 집합체 내의 모든 항목에 접근하는 방법을 제공
public interface Iterator {
boolean hasNext();
MenuItem next();
}
public class DinerMenuIterator implements Iterator {
MenuItem[] items;
int position = 0;
public DinerMenuIterator(MenuItem[] items) {
this.items = items;
}
public MenuItem next() {
/*
MenuItem menuItem = items[position];
position = position + 1;
return menuItem;
*/
// or shorten to
return items[position++];
}
public boolean hasNext() {
/*
if (position >= items.length || items[position] == null) {
return false;
} else {
return true;
}
*/
// or shorten to
return items.length > position;
}
}
public class DinerMenu {
static final int MAX_ITEMS = 6;
int numberOfItems = 0;
MenuItem[] menuItems;
public Iterator createIterator() {
return new DinerMenuIterator(menuItems);
// To test Alternating menu items, comment out above line,
// and uncomment the line below.
//return new AlternatingDinerMenuIterator(menuItems);
}
}
public class Waitress {
Menu pancakeHouseMenu;
Menu dinerMenu;
public Waitress(Menu pancakeHouseMenu, Menu dinerMenu) {
this.pancakeHouseMenu = pancakeHouseMenu;
this.dinerMenu = dinerMenu;
}
public void printMenu() {
Iterator pancakeIterator = pancakeHouseMenu.createIterator();
Iterator dinerIterator = dinerMenu.createIterator();
System.out.println("MENU\n----\nBREAKFAST");
printMenu(pancakeIterator);
System.out.println("\nLUNCH");
printMenu(dinerIterator);
}
private void printMenu(Iterator iterator) {
while (iterator.hasNext()) {
MenuItem menuItem = iterator.next();
System.out.print(menuItem.getName() + ", ");
System.out.print(menuItem.getPrice() + " -- ");
System.out.println(menuItem.getDescription());
}
}
}
public class MenuTestDrive {
public static void main(String args[]) {
Menu pancakeHouseMenu = new PancakeHouseMenu();
Menu dinerMenu = new DinerMenu();
Waitress waitress = new Waitress(pancakeHouseMenu, dinerMenu);
// With iterators
waitress.printMenu();
}
}
public interface Menu {
public Iterator<MenuItem> createIterator();
}
public class DinerMenu implements Menu {
static final int MAX_ITEMS = 6;
int numberOfItems = 0;
MenuItem[] menuItems;
public DinerMenu() {
menuItems = new MenuItem[MAX_ITEMS];
addItem("Vegetarian BLT",
"(Fakin') Bacon with lettuce & tomato on whole wheat", true, 2.99);
addItem("BLT",
"Bacon with lettuce & tomato on whole wheat", false, 2.99);
addItem("Soup of the day",
"Soup of the day, with a side of potato salad", false, 3.29);
addItem("Hotdog",
"A hot dog, with sauerkraut, relish, onions, topped with cheese",
false, 3.05);
addItem("Steamed Veggies and Brown Rice",
"A medly of steamed vegetables over brown rice", true, 3.99);
addItem("Pasta",
"Spaghetti with Marinara Sauce, and a slice of sourdough bread",
true, 3.89);
}
public void addItem(String name, String description,
boolean vegetarian, double price)
{
MenuItem menuItem = new MenuItem(name, description, vegetarian, price);
if (numberOfItems >= MAX_ITEMS) {
System.err.println("Sorry, menu is full! Can't add item to menu");
} else {
menuItems[numberOfItems] = menuItem;
numberOfItems = numberOfItems + 1;
}
}
public MenuItem[] getMenuItems() {
return menuItems;
}
public Iterator<MenuItem> createIterator() {
return new DinerMenuIterator(menuItems);
//return new AlternatingDinerMenuIterator(menuItems);
}
// other menu methods here
}
public class PancakeHouseMenu implements Menu {
ArrayList<MenuItem> menuItems;
public Iterator<MenuItem> createIterator() {
return menuItems.iterator();
}
// other menu methods here
}
public class DinerMenuIterator implements Iterator<MenuItem> {
MenuItem[] list;
int position = 0;
public DinerMenuIterator(MenuItem[] list) {
this.list = list;
}
public MenuItem next() {
MenuItem menuItem = list[position];
position = position + 1;
return menuItem;
}
public boolean hasNext() {
if (position >= list.length || list[position] == null) {
return false;
} else {
return true;
}
}
public void remove() {
if (position <= 0) {
throw new IllegalStateException
("You can't remove an item until you've done at least one next()");
}
if (list[position-1] != null) {
for (int i = position-1; i < (list.length-1); i++) {
list[i] = list[i+1];
}
list[list.length-1] = null;
}
}
}
public class Waitress {
Menu pancakeHouseMenu;
Menu dinerMenu;
Menu cafeMenu;
public Waitress(Menu pancakeHouseMenu, Menu dinerMenu, Menu cafeMenu) {
this.pancakeHouseMenu = pancakeHouseMenu;
this.dinerMenu = dinerMenu;
this.cafeMenu = cafeMenu;
}
public void printMenu() {
Iterator<MenuItem> pancakeIterator = pancakeHouseMenu.createIterator();
Iterator<MenuItem> dinerIterator = dinerMenu.createIterator();
Iterator<MenuItem> cafeIterator = cafeMenu.createIterator();
System.out.println("MENU\n----\nBREAKFAST");
printMenu(pancakeIterator);
System.out.println("\nLUNCH");
printMenu(dinerIterator);
System.out.println("\nDINNER");
printMenu(cafeIterator);
}
private void printMenu(Iterator<MenuItem> iterator) {
while (iterator.hasNext()) {
MenuItem menuItem = iterator.next();
System.out.print(menuItem.getName() + ", ");
System.out.print(menuItem.getPrice() + " -- ");
System.out.println(menuItem.getDescription());
}
}
}
하나의 클래스는 하나의 역할만 맡아야한다.
// 배열은 Iterator가 없어서 직접 구현해야함
public class AlternatingDinerMenuIterator implements Iterator<Object> {
MenuItem[] items;
int position;
public AlternatingDinerMenuIterator(MenuItem[] items) {
this.items = items;
position = Calendar.DAY_OF_WEEK % 2;
}
public Object next() {
MenuItem menuItem = items[position];
position = position + 2;
return menuItem;
}
public boolean hasNext() {
if (position >= items.length || items[position] == null) {
return false;
} else {
return true;
}
}
public void remove() {
throw new UnsupportedOperationException(
"Alternating Diner Menu Iterator does not support remove()");
}
}
public class CafeMenu implements Menu {
HashMap<String, MenuItem> menuItems = new HashMap<String, MenuItem>();
public CafeMenu() {
addItem("Veggie Burger and Air Fries",
"Veggie burger on a whole wheat bun, lettuce, tomato, and fries",
true, 3.99);
addItem("Soup of the day",
"A cup of the soup of the day, with a side salad",
false, 3.69);
addItem("Burrito",
"A large burrito, with whole pinto beans, salsa, guacamole",
true, 4.29);
}
public void addItem(String name, String description,
boolean vegetarian, double price)
{
MenuItem menuItem = new MenuItem(name, description, vegetarian, price);
menuItems.put(name, menuItem);
}
public Map<String, MenuItem> getItems() {
return menuItems;
}
public Iterator<MenuItem> createIterator() {
return menuItems.values().iterator();
}
}
public class Waitress {
ArrayList<Menu> menus;
public Waitress(ArrayList<Menu> menus) {
this.menus = menus;
}
public void printMenu() {
Iterator<?> menuIterator = menus.iterator();
while(menuIterator.hasNext()) {
Menu menu = (Menu)menuIterator.next();
printMenu(menu.createIterator());
}
}
void printMenu(Iterator<?> iterator) {
while (iterator.hasNext()) {
MenuItem menuItem = (MenuItem)iterator.next();
System.out.print(menuItem.getName() + ", ");
System.out.print(menuItem.getPrice() + " -- ");
System.out.println(menuItem.getDescription());
}
}
}
객체를 트리구조로 구성해서 부분-전체 계층구조를 구현합니다.
public abstract class MenuComponent {
public void add(MenuComponent menuComponent) {
throw new UnsupportedOperationException();
}
public void remove(MenuComponent menuComponent) {
throw new UnsupportedOperationException();
}
public MenuComponent getChild(int i) {
throw new UnsupportedOperationException();
}
public String getName() {
throw new UnsupportedOperationException();
}
public String getDescription() {
throw new UnsupportedOperationException();
}
public double getPrice() {
throw new UnsupportedOperationException();
}
public boolean isVegetarian() {
throw new UnsupportedOperationException();
}
public void print() {
throw new UnsupportedOperationException();
}
}
public class MenuItem extends MenuComponent {
String name;
String description;
boolean vegetarian;
double price;
public MenuItem(String name,
String description,
boolean vegetarian,
double price)
{
this.name = name;
this.description = description;
this.vegetarian = vegetarian;
this.price = price;
}
public String getName() {
return name;
}
public String getDescription() {
return description;
}
public double getPrice() {
return price;
}
public boolean isVegetarian() {
return vegetarian;
}
public void print() {
System.out.print(" " + getName());
if (isVegetarian()) {
System.out.print("(v)");
}
System.out.println(", " + getPrice());
System.out.println(" -- " + getDescription());
}
}
public class Menu extends MenuComponent {
ArrayList<MenuComponent> menuComponents = new ArrayList<MenuComponent>();
String name;
String description;
public Menu(String name, String description) {
this.name = name;
this.description = description;
}
public void add(MenuComponent menuComponent) {
menuComponents.add(menuComponent);
}
public void remove(MenuComponent menuComponent) {
menuComponents.remove(menuComponent);
}
public MenuComponent getChild(int i) {
return (MenuComponent)menuComponents.get(i);
}
public String getName() {
return name;
}
public String getDescription() {
return description;
}
public void print() {
System.out.print("\n" + getName());
System.out.println(", " + getDescription());
System.out.println("---------------------");
Iterator<MenuComponent> iterator = menuComponents.iterator();
while (iterator.hasNext()) {
MenuComponent menuComponent =
(MenuComponent)iterator.next();
menuComponent.print();
}
}
}
public class Waitress {
MenuComponent allMenus;
public Waitress(MenuComponent allMenus) {
this.allMenus = allMenus;
}
public void printMenu() {
allMenus.print();
}
}
public class MenuTestDrive {
public static void main(String args[]) {
MenuComponent pancakeHouseMenu =
new Menu("PANCAKE HOUSE MENU", "Breakfast");
MenuComponent dinerMenu =
new Menu("DINER MENU", "Lunch");
MenuComponent cafeMenu =
new Menu("CAFE MENU", "Dinner");
MenuComponent dessertMenu =
new Menu("DESSERT MENU", "Dessert of course!");
MenuComponent coffeeMenu = new Menu("COFFEE MENU", "Stuff to go with your afternoon coffee");
MenuComponent allMenus = new Menu("ALL MENUS", "All menus combined");
allMenus.add(pancakeHouseMenu);
allMenus.add(dinerMenu);
allMenus.add(cafeMenu);
pancakeHouseMenu.add(new MenuItem(
"K&B's Pancake Breakfast",
"Pancakes with scrambled eggs and toast",
true,
2.99));
pancakeHouseMenu.add(new MenuItem(
"Regular Pancake Breakfast",
"Pancakes with fried eggs, sausage",
false,
2.99));
pancakeHouseMenu.add(new MenuItem(
"Blueberry Pancakes",
"Pancakes made with fresh blueberries, and blueberry syrup",
true,
3.49));
pancakeHouseMenu.add(new MenuItem(
"Waffles",
"Waffles with your choice of blueberries or strawberries",
true,
3.59));
dinerMenu.add(new MenuItem(
"Vegetarian BLT",
"(Fakin') Bacon with lettuce & tomato on whole wheat",
true,
2.99));
dinerMenu.add(new MenuItem(
"BLT",
"Bacon with lettuce & tomato on whole wheat",
false,
2.99));
dinerMenu.add(new MenuItem(
"Soup of the day",
"A bowl of the soup of the day, with a side of potato salad",
false,
3.29));
dinerMenu.add(new MenuItem(
"Hot Dog",
"A hot dog, with saurkraut, relish, onions, topped with cheese",
false,
3.05));
dinerMenu.add(new MenuItem(
"Steamed Veggies and Brown Rice",
"Steamed vegetables over brown rice",
true,
3.99));
dinerMenu.add(new MenuItem(
"Pasta",
"Spaghetti with marinara sauce, and a slice of sourdough bread",
true,
3.89));
dinerMenu.add(dessertMenu);
dessertMenu.add(new MenuItem(
"Apple Pie",
"Apple pie with a flakey crust, topped with vanilla icecream",
true,
1.59));
dessertMenu.add(new MenuItem(
"Cheesecake",
"Creamy New York cheesecake, with a chocolate graham crust",
true,
1.99));
dessertMenu.add(new MenuItem(
"Sorbet",
"A scoop of raspberry and a scoop of lime",
true,
1.89));
cafeMenu.add(new MenuItem(
"Veggie Burger and Air Fries",
"Veggie burger on a whole wheat bun, lettuce, tomato, and fries",
true,
3.99));
cafeMenu.add(new MenuItem(
"Soup of the day",
"A cup of the soup of the day, with a side salad",
false,
3.69));
cafeMenu.add(new MenuItem(
"Burrito",
"A large burrito, with whole pinto beans, salsa, guacamole",
true,
4.29));
cafeMenu.add(coffeeMenu);
coffeeMenu.add(new MenuItem(
"Coffee Cake",
"Crumbly cake topped with cinnamon and walnuts",
true,
1.59));
coffeeMenu.add(new MenuItem(
"Bagel",
"Flavors include sesame, poppyseed, cinnamon raisin, pumpkin",
false,
0.69));
coffeeMenu.add(new MenuItem(
"Biscotti",
"Three almond or hazelnut biscotti cookies",
true,
0.89));
Waitress waitress = new Waitress(allMenus);
waitress.printMenu();
}
}
패턴 | 설명 |
---|---|
전략패턴 | 바뀔수 있는 행동을 캡슐화하고 어떤 행동을 적용할지 위임해서 결정한다. |
어댑터패턴 | 하나 이상의 클래스의 인터페이스를 변환한다. |
반복자패턴 | 컬렉션의 구현을 드러내지 않으면서도 컬렉션에 있는 모든 객체를 대상으로 반복작업을 할 수 있다. |
퍼사드 패턴 | 클래스의 인터페이스를 단순화한다. |
컴포지트 패턴 | 클라이언트에서 객체 컬렉션과 개별 객체를 똑같은 식으로 처리할 수 있다. |
옵저버 패턴 | 어떤 상태가 변경되었을 때 일련의 객체에게 연락할 수 있다. |
상태패턴을 이용하면 객체의 내부상태가 바뀜에 따라서 객체의 행동을 바꿀 수 있습니다. 마치 객체의 클래스가 바뀌는 것과 같은 결과를 얻을 수 있습니다.
ex) 상태 (동전없음, 동전있음, 알맹이 판매), 행동 (동전투입, 동전반환, 손잡이 돌림, 알맹이 내보냄)
// 상태패턴 적용 안한 코드
public class GumballMachine {
final static int SOLD_OUT = 0;
final static int NO_QUARTER = 1;
final static int HAS_QUARTER = 2;
final static int SOLD = 3;
int state = SOLD_OUT;
int count = 0;
public GumballMachine(int count) {
this.count = count;
if (count > 0) {
state = NO_QUARTER;
}
}
public void insertQuarter() {
if (state == HAS_QUARTER) {
System.out.println("You can't insert another quarter");
} else if (state == NO_QUARTER) {
state = HAS_QUARTER;
System.out.println("You inserted a quarter");
} else if (state == SOLD_OUT) {
System.out.println("You can't insert a quarter, the machine is sold out");
} else if (state == SOLD) {
System.out.println("Please wait, we're already giving you a gumball");
}
}
public void ejectQuarter() {
if (state == HAS_QUARTER) {
System.out.println("Quarter returned");
state = NO_QUARTER;
} else if (state == NO_QUARTER) {
System.out.println("You haven't inserted a quarter");
} else if (state == SOLD) {
System.out.println("Sorry, you already turned the crank");
} else if (state == SOLD_OUT) {
System.out.println("You can't eject, you haven't inserted a quarter yet");
}
}
public void turnCrank() {
if (state == SOLD) {
System.out.println("Turning twice doesn't get you another gumball!");
} else if (state == NO_QUARTER) {
System.out.println("You turned but there's no quarter");
} else if (state == SOLD_OUT) {
System.out.println("You turned, but there are no gumballs");
} else if (state == HAS_QUARTER) {
System.out.println("You turned...");
state = SOLD;
dispense();
}
}
private void dispense() {
if (state == SOLD) {
System.out.println("A gumball comes rolling out the slot");
count = count - 1;
if (count == 0) {
System.out.println("Oops, out of gumballs!");
state = SOLD_OUT;
} else {
state = NO_QUARTER;
}
} else if (state == NO_QUARTER) {
System.out.println("You need to pay first");
} else if (state == SOLD_OUT) {
System.out.println("No gumball dispensed");
} else if (state == HAS_QUARTER) {
System.out.println("No gumball dispensed");
}
}
public void refill(int numGumBalls) {
this.count = numGumBalls;
state = NO_QUARTER;
}
public String toString() {
StringBuffer result = new StringBuffer();
result.append("\nMighty Gumball, Inc.");
result.append("\nJava-enabled Standing Gumball Model #2004\n");
result.append("Inventory: " + count + " gumball");
if (count != 1) {
result.append("s");
}
result.append("\nMachine is ");
if (state == SOLD_OUT) {
result.append("sold out");
} else if (state == NO_QUARTER) {
result.append("waiting for quarter");
} else if (state == HAS_QUARTER) {
result.append("waiting for turn of crank");
} else if (state == SOLD) {
result.append("delivering a gumball");
}
result.append("\n");
return result.toString();
}
}
public interface State {
public void insertQuarter();
public void ejectQuarter();
public void turnCrank();
public void dispense();
public void refill();
}
public class NoQuarterState implements State {
GumballMachine gumballMachine;
public NoQuarterState(GumballMachine gumballMachine) {
this.gumballMachine = gumballMachine;
}
public void insertQuarter() {
System.out.println("You inserted a quarter");
gumballMachine.setState(gumballMachine.getHasQuarterState());
}
public void ejectQuarter() {
System.out.println("You haven't inserted a quarter");
}
public void turnCrank() {
System.out.println("You turned, but there's no quarter");
}
public void dispense() {
System.out.println("You need to pay first");
}
public void refill() { }
public String toString() {
return "waiting for quarter";
}
}
public class HasQuarterState implements State {
GumballMachine gumballMachine;
public HasQuarterState(GumballMachine gumballMachine) {
this.gumballMachine = gumballMachine;
}
public void insertQuarter() {
System.out.println("You can't insert another quarter");
}
public void ejectQuarter() {
System.out.println("Quarter returned");
gumballMachine.setState(gumballMachine.getNoQuarterState());
}
public void turnCrank() {
System.out.println("You turned...");
gumballMachine.setState(gumballMachine.getSoldState());
}
public void dispense() {
System.out.println("No gumball dispensed");
}
public void refill() { }
public String toString() {
return "waiting for turn of crank";
}
}
public class SoldOutState implements State {
GumballMachine gumballMachine;
public SoldOutState(GumballMachine gumballMachine) {
this.gumballMachine = gumballMachine;
}
public void insertQuarter() {
System.out.println("You can't insert a quarter, the machine is sold out");
}
public void ejectQuarter() {
System.out.println("You can't eject, you haven't inserted a quarter yet");
}
public void turnCrank() {
System.out.println("You turned, but there are no gumballs");
}
public void dispense() {
System.out.println("No gumball dispensed");
}
public void refill() {
gumballMachine.setState(gumballMachine.getNoQuarterState());
}
public String toString() {
return "sold out";
}
}
public class SoldState implements State {
GumballMachine gumballMachine;
public SoldState(GumballMachine gumballMachine) {
this.gumballMachine = gumballMachine;
}
public void insertQuarter() {
System.out.println("Please wait, we're already giving you a gumball");
}
public void ejectQuarter() {
System.out.println("Sorry, you already turned the crank");
}
public void turnCrank() {
System.out.println("Turning twice doesn't get you another gumball!");
}
public void dispense() {
gumballMachine.releaseBall();
if (gumballMachine.getCount() > 0) {
gumballMachine.setState(gumballMachine.getNoQuarterState());
} else {
System.out.println("Oops, out of gumballs!");
gumballMachine.setState(gumballMachine.getSoldOutState());
}
}
public void refill() { }
public String toString() {
return "dispensing a gumball";
}
}
public class GumballMachine {
State soldOutState;
State noQuarterState;
State hasQuarterState;
State soldState;
State state;
int count = 0;
public GumballMachine(int numberGumballs) {
soldOutState = new SoldOutState(this);
noQuarterState = new NoQuarterState(this);
hasQuarterState = new HasQuarterState(this);
soldState = new SoldState(this);
this.count = numberGumballs;
if (numberGumballs > 0) {
state = noQuarterState;
} else {
state = soldOutState;
}
}
public void insertQuarter() {
state.insertQuarter();
}
public void ejectQuarter() {
state.ejectQuarter();
}
public void turnCrank() {
state.turnCrank();
state.dispense();
}
void releaseBall() {
System.out.println("A gumball comes rolling out the slot...");
if (count > 0) {
count = count - 1;
}
}
int getCount() {
return count;
}
void refill(int count) {
this.count += count;
System.out.println("The gumball machine was just refilled; its new count is: " + this.count);
state.refill();
}
void setState(State state) {
this.state = state;
}
public State getState() {
return state;
}
public State getSoldOutState() {
return soldOutState;
}
public State getNoQuarterState() {
return noQuarterState;
}
public State getHasQuarterState() {
return hasQuarterState;
}
public State getSoldState() {
return soldState;
}
public String toString() {
StringBuffer result = new StringBuffer();
result.append("\nMighty Gumball, Inc.");
result.append("\nJava-enabled Standing Gumball Model #2004");
result.append("\nInventory: " + count + " gumball");
if (count != 1) {
result.append("s");
}
result.append("\n");
result.append("Machine is " + state + "\n");
return result.toString();
}
}
패턴 | 설명 |
---|---|
상태패턴 | 상태를 기반으로 하는 행동을 캡슐화하고 행동을 현재 상태에게 위임합니다. |
전략패턴 | 바꿔 쓸 수 있는 행동을 캡슐화한 다음, 실제 행동은 다른 객체에게 위임합니다. |
템플릿 메소드 패턴 | 알고리즘의 각 단계를 구현하는 방법을 서브클래스에서 구현합니다. |
원격 프록시는 원격 객체의 로컬 대변자 역할 한다.
public interface Person {
String getName();
String getGender();
String getInterests();
int getGeekRating();
void setName(String name);
void setGender(String gender);
void setInterests(String interests);
void setGeekRating(int rating);
}
public class PersonImpl implements Person {
String name;
String gender;
String interests;
int rating;
int ratingCount = 0;
public String getName() {
return name;
}
public String getGender() {
return gender;
}
public String getInterests() {
return interests;
}
public int getGeekRating() {
if (ratingCount == 0) return 0;
return (rating/ratingCount);
}
public void setName(String name) {
this.name = name;
}
public void setGender(String gender) {
this.gender = gender;
}
public void setInterests(String interests) {
this.interests = interests;
}
public void setGeekRating(int rating) {
this.rating += rating;
ratingCount++;
}
}
public class NonOwnerInvocationHandler implements InvocationHandler {
Person person;
public NonOwnerInvocationHandler(Person person) {
this.person = person;
}
public Object invoke(Object proxy, Method method, Object[] args)
throws IllegalAccessException {
try {
if (method.getName().startsWith("get")) {
return method.invoke(person, args);
} else if (method.getName().equals("setGeekRating")) {
return method.invoke(person, args);
} else if (method.getName().startsWith("set")) {
throw new IllegalAccessException();
}
} catch (InvocationTargetException e) {
e.printStackTrace();
}
return null;
}
}
public class OwnerInvocationHandler implements InvocationHandler {
Person person;
public OwnerInvocationHandler(Person person) {
this.person = person;
}
public Object invoke(Object proxy, Method method, Object[] args)
throws IllegalAccessException {
try {
if (method.getName().startsWith("get")) {
return method.invoke(person, args);
} else if (method.getName().equals("setGeekRating")) {
throw new IllegalAccessException();
} else if (method.getName().startsWith("set")) {
return method.invoke(person, args);
}
} catch (InvocationTargetException e) {
e.printStackTrace();
}
return null;
}
}
public class MatchMakingTestDrive {
HashMap<String, Person> datingDB = new HashMap<String, Person>();
public static void main(String[] args) {
MatchMakingTestDrive test = new MatchMakingTestDrive();
test.drive();
}
public MatchMakingTestDrive() {
initializeDatabase();
}
public void drive() {
Person joe = getPersonFromDatabase("Joe Javabean");
Person ownerProxy = getOwnerProxy(joe);
System.out.println("Name is " + ownerProxy.getName());
ownerProxy.setInterests("bowling, Go");
System.out.println("Interests set from owner proxy");
try {
ownerProxy.setGeekRating(10);
} catch (Exception e) {
System.out.println("Can't set rating from owner proxy");
}
System.out.println("Rating is " + ownerProxy.getGeekRating());
Person nonOwnerProxy = getNonOwnerProxy(joe);
System.out.println("Name is " + nonOwnerProxy.getName());
try {
nonOwnerProxy.setInterests("bowling, Go");
} catch (Exception e) {
System.out.println("Can't set interests from non owner proxy");
}
nonOwnerProxy.setGeekRating(3);
System.out.println("Rating set from non owner proxy");
System.out.println("Rating is " + nonOwnerProxy.getGeekRating());
}
Person getOwnerProxy(Person person) {
return (Person) Proxy.newProxyInstance(
person.getClass().getClassLoader(),
person.getClass().getInterfaces(),
new OwnerInvocationHandler(person));
}
Person getNonOwnerProxy(Person person) {
return (Person) Proxy.newProxyInstance(
person.getClass().getClassLoader(),
person.getClass().getInterfaces(),
new NonOwnerInvocationHandler(person));
}
Person getPersonFromDatabase(String name) {
return (Person)datingDB.get(name);
}
void initializeDatabase() {
Person joe = new PersonImpl();
joe.setName("Joe Javabean");
joe.setInterests("cars, computers, music");
joe.setGeekRating(7);
datingDB.put(joe.getName(), joe);
Person kelly = new PersonImpl();
kelly.setName("Kelly Klosure");
kelly.setInterests("ebay, movies, music");
kelly.setGeekRating(6);
datingDB.put(kelly.getName(), kelly);
}
}
패턴 | 설명 |
---|---|
데코레이터 | 다른 객체를 감싸서 새로운 행동을 추가해 준다. |
퍼사드 | 여러 객체를 감싸서 인터페이스를 단순하게 만든다. |
프록시 | 다른 객체를 감싸서 접근을 제어합니다. |
어댑터 | 다른 객체를 감싸서 다른 인터페이스를 제공 |
// State Pattern: Define the Grade interface
interface Grade {
void upgrade(User user);
void downgrade(User user);
}
// Concrete grade classes
class RookieGrade implements Grade {
@Override
public void upgrade(User user) {
// Implement upgrade logic from Rookie to Pro
}
@Override
public void downgrade(User user) {
// Implement downgrade logic from Rookie to a lower grade (if applicable)
}
}
class ProGrade implements Grade {
@Override
public void upgrade(User user) {
// Implement upgrade logic from Pro to Partner
}
@Override
public void downgrade(User user) {
// Implement downgrade logic from Pro to Rookie
}
}
class PartnerGrade implements Grade {
@Override
public void upgrade(User user) {
// Implement upgrade logic from Partner (if applicable)
}
@Override
public void downgrade(User user) {
// Implement downgrade logic from Partner to Pro (if applicable)
}
}
// Strategy Pattern: Define upgrade strategy interface
interface UpgradeStrategy {
boolean canUpgrade(User user);
}
// Concrete upgrade strategies
class RookieToProUpgradeStrategy implements UpgradeStrategy {
@Override
public boolean canUpgrade(User user) {
// Implement conditions and policies for upgrading from Rookie to Pro
}
}
class RookieToPartnerUpgradeStrategy implements UpgradeStrategy {
@Override
public boolean canUpgrade(User user) {
// Implement conditions and policies for upgrading from Rookie to Partner
}
}
class ProToPartnerUpgradeStrategy implements UpgradeStrategy {
@Override
public boolean canUpgrade(User user) {
// Implement conditions and policies for upgrading from Pro to Partner
}
}
// Factory Method Pattern: Factory for creating upgrade strategies
class UpgradeStrategyFactory {
public static UpgradeStrategy createUpgradeStrategy(Grade currentGrade, Grade targetGrade) {
if (currentGrade instanceof RookieGrade) {
if (targetGrade instanceof ProGrade) {
return new RookieToProUpgradeStrategy();
} else if (targetGrade instanceof PartnerGrade) {
return new RookieToPartnerUpgradeStrategy();
}
} else if (currentGrade instanceof ProGrade && targetGrade instanceof PartnerGrade) {
return new ProToPartnerUpgradeStrategy();
}
// Handle unsupported grade changes
throw new IllegalArgumentException("Unsupported grade change");
}
}
// Context class
class User {
private Grade currentGrade;
public void upgrade(Grade targetGrade) {
UpgradeStrategy upgradeStrategy = UpgradeStrategyFactory.createUpgradeStrategy(currentGrade, targetGrade);
if (upgradeStrategy.canUpgrade(this)) {
targetGrade.upgrade(this);
currentGrade = targetGrade;
}
}
public void downgrade(Grade targetGrade) {
targetGrade.downgrade(this);
currentGrade = targetGrade;
}
}
객체 지향의 원칙
Strategy Pattern (캡슐화가 포인트)
알고리즘 군을 정희하고 캡슐화해서 각각의 알고리즘군을 수정해서 쓸 수 있게 해줍니다. 오리의 행동중에 나는것, 소리나는 것이있는데 나는것, 소리나는것 모두 각각 캡슐화
Observer Pattern
한 객체의 상태가 바뀌면 그 객체에 의존하는 다른 객채에게 연락이 가고 자동으로 내용이 갱신되는 방식 (one-to-many) Weather 데이터가 바뀌면 관찰자 Observer들의 display도 함께 바꿔줘야한다.