자바 디자인 패턴(3)_전략 패턴

전략 패턴

• 객체의 행위를 바꾸고 싶을 때 캡슐화한 알고리즘 컨텍스트 안에서 바꿔주면서 상호 교체가 가능하게 만드는 패턴

 

// 결제 방식(전략)만 바꿔서 결제하는 로직
import java.util.*;

interface PaymentStrategy {
    public void pay(int amount);
}

class KAKAOCardStrategy implements PaymentStrategy {
    private String name;
    private String cardNumber;
    private String cvv;
    private String dateOfExpiry;
    
    public KAKAOCardStrategy(String nm, String ccNum, String cvv, String expiryDate) {
        this.name = nm;
        this.cardNumber = ccNum;
        this.cvv = cvv;
        this.dateOfExpiry = expiryDate;
    }
    
    @Override
    public void pay(int amount) {
        System.out.println(amount+" paid KAKAO");
    }
}

class LUNACardStrategy implements PaymentStrategy {
    private String emailId;
    private String password;
    
    public LUNACardStrategy(String email, String pwd) {
        this.emailId = email;
        this.password = pwd;
    }
    
    @Override
    public void pay(int amount) {
        System.out.println(amount+" paid LUNA");
    }
}

class Item {
    private String name;
    private int price;
    
    public Item(String name, int cost) {
        this.name = name;
        this.price = cost;
    }
    
    public String getName() {
        return name;
    }
    
    public int getPrice() {
        return price;
    }
}

class ShoppingCart {
    List<Item> items;
    
    public ShoppingCart() {
        this.items = new ArrayList<Item>();
    }
    
    public void addItem(Item item) {
        this.items.add(item);
    }
    
    public int calculateTot() {
        int sum = 0;
        for (Item item : items) {
            sum += item.getPrice();
        }
        return sum;
    }
    
    public void pay(PaymentStrategy payMethod) {
        int amount = calculateTot();
        payMethod.pay(amount);
    }
}

public class HelloWorld{
     public static void main(String []args){
        ShoppingCart cart = new ShoppingCart();
        
        Item a = new Item("A", 100);
        Item b = new Item("B", 200);
        
        cart.addItem(a);
        cart.addItem(b);
        
        cart.pay(new LUNACardStrategy("email@email.com", "password")); // 300 paid LUNA
        cart.pay(new KAKAOCardStrategy("kwak", "123", "456", "11/06")); // 300 paid KAKAO
     }
}

 

 

 

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