Implementing the Facade design pattern

Let's look into the following listings to demonstrate the Facade design pattern.

Create subsystem service classes for your Bank application: Let's see the following PaymentService class for the subsystem.

Following is the PaymentService.java file:

    package com.packt.patterninspring.chapter3.facade.pattern; 
    public class PaymentService { 
      public static boolean doPayment(){ 
         return true; 
      } 
    } 

Let's create another service class AccountService for the subsystem.

Following is the AccountService.java file:

   package com.packt.patterninspring.chapter3.facade.pattern; 
   import com.packt.patterninspring.chapter3.model.Account; 
   import com.packt.patterninspring.chapter3.model.SavingAccount; 
   public class AccountService { 
     public static Account getAccount(String accountId) { 
        return new SavingAccount(); 
     } 
   } 

Let's create another service class TransferService for the subsystem.

Following is the TransferService.java file:

    package com.packt.patterninspring.chapter3.facade.pattern; 
    import com.packt.patterninspring.chapter3.model.Account; 
    public class TransferService { 
      public static void transfer(int amount, Account fromAccount,
            Account toAccount) { 
        System.out.println("Transfering Money"); 
      } 
    } 

Create a Facade Service class to interact with the subsystem: Let's see the following Facade interface for the subsystem and then implement this Facade interface as a global banking service in the application.

Following is the BankingServiceFacade.java file:

    package com.packt.patterninspring.chapter3.facade.pattern; 
    public interface BankingServiceFacade { 
       void moneyTransfer(); 
    } 

Following is the BankingServiceFacadeImpl.java file:

    package com.packt.patterninspring.chapter3.facade.pattern; 
    import com.packt.patterninspring.chapter3.model.Account; 
    public class BankingServiceFacadeImpl implements 
        BankingServiceFacade{ 
      @Override 
      public void moneyTransfer() { 
         if(PaymentService.doPayment()){ 
               Account fromAccount = AccountService.getAccount("1"); 
               Account toAccount   = AccountService.getAccount("2"); 
               TransferService.transfer(1000, fromAccount, toAccount); 
         } 
      } 
    } 

Create the client of the Facade:

Following is the FacadePatternClient.java file:

    package com.packt.patterninspring.chapter3.facade.pattern; 
    public class FacadePatternClient { 
      public static void main(String[] args) { 
        BankingServiceFacade serviceFacade = new 
          BankingServiceFacadeImpl(); 
        serviceFacade.moneyTransfer(); 
      } 
    }