آموزش الگوی طراحی بیلدر (Builder) جاوا

package builder;

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

// Packing interface 
package builder;

public interface Packing {

    public String pack();
}

// Bottle class 
package builder;

public class Bottle implements Packing {

   @Override public String pack(){
       return "Bottle";
   }
}

// Wrapper class 
package builder;

public class Wrapper implements Packing {

   @Override public String pack(){
       return "Wrapper";
   }
}

// Burger class
package builder;

public abstract class Burger implements Item {

   @Override public Packing packing() {
      return new Wrapper();
   }
}

// ColdDrink class
package builder;

public abstract class ColdDrink implements Item {
    
    @Override public Packing packing() {
        return new Bottle();
    }    
}

// VegBurger class 
package builder;

public class VegBurger extends Burger {
    
    @Override public float price() {
        return 25.0f;
    }
    
    @Override public String name() {
        return "Veg Burger";
    }
}
// ChickenBurger class 
package builder;

public class ChickenBurger extends Burger {
    
    @Override public float price(){
        return 50.5f;
    }
    
    @Override public String name(){
        return "Chicken Burger";
   }
}

// Pepsi class 
package builder;

public class Pepsi extends ColdDrink {

   @Override public float price() {
      return 35.0f;
   }

   @Override public String name() {
      return "Pepsi";
   }
}
// Coke class 
package builder;

public class Coke extends ColdDrink {

   @Override public float price() {
      return 30.0f;
   }

   @Override public String name() {
      return "Coke";
   }
}

// BurgerType enum 
package builder;

public enum BurgerType {    
    chicken(1),
    veg(2);
        
    int id;
    private BurgerType(int id) {
        this.id = id;
    }
    public int getId() {
        return id;
    }    
}
// BurgerType enum 
package builder;

public enum ColdDrinkType {    
    pepsi(1),
    coke(2);        
    int id;

    private ColdDrinkType(int id) {
        this.id = id;
    }
    public int getId() {
        return id;
    }    
}

package builder;

import java.util.ArrayList;
import java.util.List;

public class Meal {
    
   private List<Item> items = new ArrayList<Item>();	

   public void addItem(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.print("Item : " + item.name());
         System.out.print(", Packing : " + item.packing().pack());
         System.out.println(", Price : " + item.price());
      }		
   }	
}

package builder;

public class MealBuilder {

   public Meal prepare(BurgerType bType, ColdDrinkType cdType) {
      Meal meal = new Meal();
      
      Burger    burger    = getBurger(bType);
      ColdDrink coldDrink = getColdDrink(cdType);
      
      meal.addItem(burger);
      meal.addItem(coldDrink);
      return meal;
   }   
   
   private Burger getBurger(BurgerType type){
       switch(type){
          case chicken:   return new ChickenBurger();
          case veg:       return new VegBurger();
          default:        return new ChickenBurger(); // ChickenBurger is default
      }
   }
   
   private ColdDrink getColdDrink(ColdDrinkType type){
       switch(type){
          case pepsi:     return new Pepsi();
          case coke:      return new Coke();
          default:        return new Pepsi(); // Pepsi is default
      }
   }
}

package builder;

public class BuilderPatternDemo {
   public static void main(String[] args) {
   
      MealBuilder mealBuilder = new MealBuilder();

      Meal vegMeal = mealBuilder.prepare(BurgerType.veg, ColdDrinkType.coke);
      System.out.println("Veg Meal");
      vegMeal.showItems();
      System.out.println("Total Cost: " + vegMeal.getCost());

      Meal nonVegMeal = mealBuilder.prepare(BurgerType.chicken, ColdDrinkType.pepsi);
      System.out.println("\n\nChicken Meal");
      nonVegMeal.showItems();
      System.out.println("Total Cost: " + nonVegMeal.getCost());
   }
}