业务代表模式

业务代表模式（Business Delegate Pattern）用于对表示层和业务层解耦。它基本上是用来减少通信或对表示层代码中的业务层代码的远程查询功能。在业务层中我们有以下实体。

实现

我们将创建 Client、BusinessDelegate、BusinessService、LookUpService、JMSService 和 EJBService 来表示业务代表模式中的各种实体。

BusinessDelegatePatternDemo，我们的演示类使用 BusinessDelegate 和 Client 来演示业务代表模式的用法。

步骤 1

创建 BusinessService 接口。

public interface BusinessService {
   public void doProcessing();
}

步骤 2

创建实体服务类。

public class EJBService implements BusinessService {

   @Override
   public void doProcessing() {
      System.out.println("Processing task by invoking EJB Service");
   }
}

public class JMSService implements BusinessService {

   @Override
   public void doProcessing() {
      System.out.println("Processing task by invoking JMS Service");
   }
}

步骤 3

创建业务查询服务。

public class BusinessLookUp {
   public BusinessService getBusinessService(String serviceType){
      if(serviceType.equalsIgnoreCase("EJB")){
         return new EJBService();
      }else {
         return new JMSService();
      }
   }
}

步骤 4

创建业务代表。

public class BusinessDelegate {
   private BusinessLookUp lookupService = new BusinessLookUp();
   private BusinessService businessService;
   private String serviceType;

   public void setServiceType(String serviceType){
      this.serviceType = serviceType;
   }

   public void doTask(){
      businessService = lookupService.getBusinessService(serviceType);
      businessService.doProcessing();      
   }
}

步骤 5

创建客户端。

public class Client {

   BusinessDelegate businessService;

   public Client(BusinessDelegate businessService){
      this.businessService  = businessService;
   }

   public void doTask(){     
      businessService.doTask();
   }
}

步骤 6

使用 BusinessDelegate 和 Client 类来演示业务代表模式。

public class BusinessDelegatePatternDemo {

   public static void main(String[] args) {

      BusinessDelegate businessDelegate = new BusinessDelegate();
      businessDelegate.setServiceType("EJB");

      Client client = new Client(businessDelegate);
      client.doTask();

      businessDelegate.setServiceType("JMS");
      client.doTask();
   }
}

步骤 7

验证输出。

Processing task by invoking EJB Service
Processing task by invoking JMS Service