Command pattern

Command pattern

-behavioral pattern에 속하며, data driven pattern이다.

-request는 command로 객체 안에 wrapping 되어 invoker 객체에 건내진다.

-invoker는 command를 다룰 수 있는 적절한 객체를 찾고 전달하여 command를 실행한다.

Order interface는 command로 사용하기 위해 만들어졌다.

Order는 command를 실제로 처리하는 역할

Stock은 request로써 만들어지며, Order에 wrapping된다.

Broker는 Invoker로써 동작하여 명령을 내리는데 사용된다.

Main 호출 부

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//make a request Stock abcStock=new Stock(); //make commands Order buy = new BuyStock(abcStock); Order sell = new SellStock(abcStock); Broker broker =new Broker();   //pass commands to invoker broker.takeOrder(buy); broker.takeOrder(sell);   //execution broker.placeOrders();

Stock.java

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/**  * request class  */ public class Stock {     public static String TAG = "Stock";     private String name ="ABC";     private int quantity = 10;       public void buy(){         Log.d(TAG, "Stock [ Name: "+name+", Quantity: " + quantity +" ] bought");     }     public void sell(){         Log.d(TAG, "Stock [ Name: "+name+", Quantity: " + quantity +" ] sold");     } }

Broker.java

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/**  * Invoker class  */ public class Broker {     private List<order>  orderList = new ArrayList<order>();       public void takeOrder(Order order){         orderList.add(order);     }     public void placeOrders(){           for ( Order o : orderList){             o.execute();         }         orderList.clear();     } } </order></order>

나머지

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public interface Order {     void execute(); }   public class SellStock implements Order {       private final Stock abcStock;       SellStock(Stock abcStock){         this.abcStock=abcStock;     }       @Override     public void execute() {         abcStock.sell();     } }   public class BuyStock implements Order {       private final Stock abcStock;       public BuyStock(Stock abcStock){         this.abcStock=abcStock;     }       @Override     public void execute() {         abcStock.buy();     } }

결과:

07-20 17:22:27.275 16908 16908 D Stock   : Stock [ Name: ABC, Quantity: 10 ] bought

07-20 17:22:27.275 16908 16908 D Stock   : Stock [ Name: ABC, Quantity: 10 ] sold

출처 :

https://www.tutorialspoint.com/design_pattern/command_pattern.htm