1.簡(jiǎn)介
業(yè)務(wù)代表模式用于對(duì)表示層和業(yè)務(wù)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(wù)層代碼的遠(yuǎn)程查詢功能烛缔。在業(yè)務(wù)層中我們有以下實(shí)體馏段。
- 客戶端（Client） - 表示層代碼可以是 JSP轩拨、servlet 或 UI java 代碼。
- 業(yè)務(wù)代表（Business Delegate） - 一個(gè)為客戶端實(shí)體提供的入口類院喜，它提供了對(duì)業(yè)務(wù)服務(wù)方法的訪問亡蓉。
- 查詢服務(wù)（LookUp Service） - 查找服務(wù)對(duì)象負(fù)責(zé)獲取相關(guān)的業(yè)務(wù)實(shí)現(xiàn)，并提供業(yè)務(wù)對(duì)象對(duì)業(yè)務(wù)代表對(duì)象的訪問喷舀。
- 業(yè)務(wù)服務(wù)（Business Service） - 業(yè)務(wù)服務(wù)接口砍濒。實(shí)現(xiàn)了該業(yè)務(wù)服務(wù)的實(shí)體類，提供了實(shí)際的業(yè)務(wù)實(shí)現(xiàn)邏輯硫麻。
2.實(shí)現(xiàn)
我們將創(chuàng)建 Client爸邢、BusinessDelegate、BusinessService拿愧、LookUpService杠河、JMSService 和 EJBService 來表示業(yè)務(wù)代表模式中的各種實(shí)體。
BusinessDelegatePatternDemo赶掖，我們的演示類使用 BusinessDelegate 和 Client 來演示業(yè)務(wù)代表模式的用法感猛。
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1.創(chuàng)建 BusinessService 接口
public interface BusinessService {
public void doProcessing();
}
2.創(chuàng)建實(shí)體服務(wù)類
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");
}
}
3.創(chuàng)建業(yè)務(wù)查詢服務(wù)
public class BusinessLookUp {
public BusinessService getBusinessService(String serviceType){
if(serviceType.equalsIgnoreCase("EJB")){
return new EJBService();
}else {
return new JMSService();
}
}
}
4.創(chuàng)建業(yè)務(wù)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();
}
}
5.創(chuàng)建客戶端
public class Client {
BusinessDelegate businessService;
public Client(BusinessDelegate businessService){
this.businessService = businessService;
}
public void doTask(){
businessService.doTask();
}
}
6.使用 BusinessDelegate 和 Client 類來演示業(yè)務(wù)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();
}
}
7.執(zhí)行程序七扰，輸出結(jié)果
Processing task by invoking EJB Service
Processing task by invoking JMS Service
