業(yè)務代表模式
業(yè)務代表模式(Business Delegate Pattern)用于對表示層和業(yè)務層解耦。它基本上是用來減少通信或?qū)Ρ硎緦哟a中的業(yè)務層代碼的遠程查詢功能。在業(yè)務層中我們有以下實體。
客戶端(Client) - 表示層代碼可以是 JSP、servlet 或 UI java 代碼。
業(yè)務代表(Business Delegate) - 一個為客戶端實體提供的入口類,它提供了對業(yè)務服務方法的訪問。
查詢服務(LookUp Service) - 查找服務對象負責獲取相關(guān)的業(yè)務實現(xiàn),并提供業(yè)務對象對業(yè)務代表對象的訪問。
業(yè)務服務(Business Service) - 業(yè)務服務接口。實現(xiàn)了該業(yè)務服務的實體類,提供了實際的業(yè)務實現(xiàn)邏輯。
實現(xiàn)
我們將創(chuàng)建 Client、BusinessDelegate、BusinessService、LookUpService、JMSService 和 EJBService 來表示業(yè)務代表模式中的各種實體。
BusinessDelegatePatternDemo,我們的演示類使用 BusinessDelegate 和 Client 來演示業(yè)務代表模式的用法。

步驟 1
創(chuàng)建 BusinessService 接口。
BusinessService.java
public interface BusinessService { public void doProcessing(); }
步驟 2
創(chuàng)建實體服務類。
EJBService.java
public class EJBService implements BusinessService { @Override public void doProcessing() { System.out.println("Processing task by invoking EJB Service"); } }
JMSService.java
public class JMSService implements BusinessService { @Override public void doProcessing() { System.out.println("Processing task by invoking JMS Service"); } }
步驟 3
創(chuàng)建業(yè)務查詢服務。
BusinessLookUp.java
public class BusinessLookUp { public BusinessService getBusinessService(String serviceType){ if(serviceType.equalsIgnoreCase("EJB")){ return new EJBService(); }else { return new JMSService(); } } }
步驟 4
創(chuàng)建業(yè)務代表。
BusinessDelegate.java
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(); } }
步驟 5
創(chuàng)建客戶端。
Student.java
public class Client { BusinessDelegate businessService; public Client(BusinessDelegate businessService){ this.businessService = businessService; } public void doTask(){ businessService.doTask(); } }
步驟 6
使用 BusinessDelegate 和 Client 類來演示業(yè)務代表模式。
BusinessDelegatePatternDemo.java
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(); } }
步驟 7
驗證輸出。
Processing task by invoking EJB Service Processing task by invoking JMS Service