[자바 디자인 패턴] 생성패턴 - 빌더 패턴

생성패턴 목록

• 팩토리 메소드 패턴 (Factory Method Pattern)
• 추상 팩토리 패턴 (Abstract Factory Pattern)
• 싱글톤 패턴 (Singleton Pattern)
• 프로토타입 패턴 (Prototype Pattern)
• 빌더 패턴 (Builder Pattern)
• 오브젝트 풀 패턴 (Object Pool Pattern)

 

객체의 구성과 표현을 명확히 해야하는 경우에 필요한 것 같다.

하지만 추상적으로 정의되어있는 상태에서는 함부로 적용할 수 있는 패턴이 아닌 것 같다.

장점

- 객체의 구성과 표현을 명확하게 구분합니다.

- 프로세스를 보다 잘 제어할 수 있습니다.

- 객체의 내부 표현 변경을 지원합니다.

 

사용시기

- 단일 단계에서 개체를 만들 수 없을 때

 

UML

 

Interface Class : Item

public interface Item{
    public String name();
    public String size();
    public float price();
}

 

Implement Class : Pizza, ColdDrink

public abstract class Pizza implements Item{
    @Override
    public abstract float price();
}

public abstract class ColdDrink implements Item{
    @Override
    public abstract float price();
}

 

Extend Class

- VegPizza

  > MediumCheezePizza

  > LargeCheezePizza

public abstract class VegPizza extends Pizza{
    @Override
    public abstract float price();
    
    @Override
    public abstract String name();
    
    @Override
    public abstract String size();
}

public class MediumCheezePizza extends VegPizza{
    @Override
    public float price(){
        return 220.0f;
    }
    
    @Override
    public String name(){
        return "Cheeze Pizza";
    }
    
    @Override
    public String size(){
        return "Medium Size";
    }
}

public class LargeCheezePizza extends VegPizza{
    @Override
    public float price(){
        return 260.0f;
    }
    
    @Override
    public String name(){
        return "Cheeze Pizza";
    }
    
    @Override
    public String size(){
        return "Large Size";
    }
}

 

- NonVegPizza

  > MediumNonVegPizza

  > LargeNonVegPizza

public abstract class NonVegPizza extends Pizza{
    @Override
    public abstract float price();
    
    @Override
    public abstract String name();
    
    @Override
    public abstract String size();
}

public class MediumNonVegPizza extends NonVegPizza{
    @Override
    public float price(){
        return 200.0f;
    }
    
    @Override
    public String name(){
        return "Non-Veg Pizza";
    }
    
    @Override
    public String size(){
        return "Medium Size";
    }
}

public class LargeNonVegPizza extends NonVegPizza{
    @Override
    public float price(){
        return 220.0f;
    }
    
    @Override
    public String name(){
        return "Non-Veg Pizza";
    }
    
    @Override
    public String size(){
        return "Large Size";
    }
}

 

- Pepsi

  > MediumPepsi

  > LargePepsi

public abstract class Pepsi extends ColdDrink{
    @Override
    public abstract float price();
    
    @Override
    public abstract String name();
    
    @Override
    public abstract String size();
}

public class MediumPepsi extends Pepsi{
    @Override
    public float price(){
        return 35.0f;
    }
    
    @Override
    public String name(){
        return "500 ml Pepsi";
    }
    
    @Override
    public String size(){
        return "Medium Size";
    }
}

public class LargePepsi extends Pepsi{
    @Override
    public float price(){
        return 50.0f;
    }
    
    @Override
    public String name(){
        return "750 ml Pepsi";
    }
    
    @Override
    public String size(){
        return "Large Size";
    }
}

 

- Coke

  > MediumCoke

  > LargeCoke

public abstract class Coke extends ColdDrink{
    @Override
    public abstract float price();
    
    @Override
    public abstract String name();
    
    @Override
    public abstract String size();
}

public class MediumCoke extends Coke{
    @Override
    public float price(){
        return 35.0f;
    }
    
    @Override
    public String name(){
        return "500 ml Coke";
    }
    
    @Override
    public String size(){
        return "Medium Size";
    }
}

public class LargeCoke extends Coke{
    @Override
    public float price(){
        return 50.0f;
    }
    
    @Override
    public String name(){
        return "750 ml Coke";
    }
    
    @Override
    public String size(){
        return "Large Size";
    }
}

 

Operation Class : OrderedItems, OrderBuilder, BuilderDemo

public class OrderedItems{
    List<Item> items = new ArrayList<Item>();
    
    public void addItems(Item item){
        items.add(item);
    }
    
    public float getCost(){
        float cost = 0.0f;
        
        for(Item item : items){
            cost += item.price();
        }
        
        return cost;
    }
    
    public void showItems(){
        for(Item item : items){
            System.out.println("Item is : " + item.name());
            System.out.println("Size is : " + item.size());
            System.out.println("Price is : " + item.price());
        }
    }
}

public class Orderbuilder{
    public OrderedItems preparePizza() throws IOException{
        OrderedItems itemsOrder = new OrderedItems();
        
        // Pizza
        itemsOrder.addItems(new MediumCheezePizza());
        itemsOrder.addItems(new LargeCheezePizza());
        itemsOrder.addItems(new MediumNonVegPizza());
        itemsOrder.addItems(new LargeNonVegPizza());
        
        // Drink
        itemsOrder.addItems(new MediumPepsi());
        itemsOrder.addItems(new LargePepsi());
        itemsOrder.addItems(new MediumCoke());
        itemsOrder.addItems(new LargeCoke());
        
        return itemsOrder;
    }
}

public class BuilderDemo{
    public static void main(String[] args) throws IOException{
        OrderBuilder builder = new OrderBuilder();
        
        OrderedItems orderedItems = builder.preparePizza();
        orderedItems.showItems();
        
        System.out.println("");
        System.out.println("Total Cost : " + orderedItems.getCost());
    }
}

 

출처 : https://www.javatpoint.com/

know-one-by-one.tistory.com/37