业务事件模型的实现
在实际业务开发过程中，很经常应用到观察者模式。大致的处理流程是说在模块初始化的时候，注册若干观察者，然后它们处理自己感兴趣的内容。当某一个具体的事件发生的时候，遍历观察者队列，然后”观察者“们就根据之前约定的具体情况，处理自己关注的事件。其实观察者模式本人认为更确切的说法应该是：事件通知模型。那么现在，我们就用传统的Java语言来实现一下（具体可以查看代码的注释，写的挺详细了）。
业务事件定义如下：
/** * @filename:BusinessEvent.java * * Newland Co. Ltd. All rights reserved. * * @Description:业务事件定义 * @author tangjie * @version 1.0 * */ package newlandframework.businessevent; public class BusinessEvent { // 某种具体的业务事件的数据内容 private Object businessData; // 某种具体的业务事件的事件类型 private String businessEventType; public BusinessEvent(String businessEventType, Object businessData) { this.businessEventType = businessEventType; this.businessData = businessData; } public Object getBusinessData() { return this.businessData; } public String getBusinessEventType() { return this.businessEventType; } }
接着就是业务事件监听器的定义了
/** * @filename:BusinessEventListener.java * * Newland Co. Ltd. All rights reserved. * * @Description:业务事件监听器定义 * @author tangjie * @version 1.0 * */ package newlandframework.businessevent; public interface BusinessEventListener { //事件接口定义 public void execute(BusinessEvent event); }
业务事件，总要有个管理者吧，那现在就实现一个
/** * @filename:BusinessEventManagement.java * * Newland Co. Ltd. All rights reserved. * * @Description:业务事件管理器定义 * @author tangjie * @version 1.0 * */ package newlandframework.businessevent; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; //业务事件管理器 public class BusinessEventManagement { private Map<String, List<BusinessEventListener>> map = new HashMap<String, List<BusinessEventListener>>(); public BusinessEventManagement() { } // 注册业务事件监听器 public boolean addBusinessEventListener(String BusinessEventType,BusinessEventListener listener) { List<BusinessEventListener> listeners = map.get(BusinessEventType); if (null == listeners) { listeners = new ArrayList<BusinessEventListener>(); } boolean result = listeners.add(listener); map.put(BusinessEventType, listeners); return result; } // 移除业务事件监听器 public boolean removeBusinessEventListener(String BusinessEventType,BusinessEventListener listener) { List<BusinessEventListener> listeners = map.get(BusinessEventType);
if (null != listeners) { return listeners.remove(listener); } return false; } // 获取业务事件监听器队列 public List<BusinessEventListener> getBusinessEventListeners(String BusinessEventType) { return map.get(BusinessEventType); } }
再来一个事件的发送者，来负责事件的派发
/** * @filename:BusinessEventNotify.java * * Newland Co. Ltd. All rights reserved. * * @Description:业务事件发送者 * @author tangjie * @version 1.0 * */ package newlandframework.businessevent; import java.util.List; public class BusinessEventNotify { private BusinessEventManagement businessEventManagement;; public BusinessEventNotify(BusinessEventManagement businessEventManagement) { this.businessEventManagement = businessEventManagement; } // 事件派发 public void notify(BusinessEvent BusinessEvent) { if (null == BusinessEvent) { return; } List<BusinessEventListener> listeners = businessEventManagement.getBusinessEventListeners(BusinessEvent.getBusinessEventType()); if (null == listeners) { return; } for (BusinessEventListener listener : listeners) { listener.execute(BusinessEvent); } } }
关键的来了，下面可以根据自己的业务规定，注册若干个事件的监听器。下面我们就先注册两个监听器，分别是短信监听器、彩铃监听器，然后执行自己对“感兴趣”事件进行的操作。
/** * @filename:SendSmsListener.java * * Newland Co. Ltd. All rights reserved. * * @Description:短信消息监听器 * @author tangjie * @version 1.0 * */ package newlandframework.businessevent; public class SendSmsListener implements BusinessEventListener { @Override public void execute(BusinessEvent event) { System.out.println("监听器:" + this + "接收到业务事件，业务事件类型是[" + event.getBusinessEventType() + "] ## 业务事件附带的数据[" + event.getBusinessData() + "]"); } }
/** * @filename:ColorRingListener.java * * Newland Co. Ltd. All rights reserved. * * @Description:彩铃消息监听器 * @author tangjie * @version 1.0 * */ package newlandframework.businessevent; public class ColorRingListener implements BusinessEventListener { @Override public void execute(BusinessEvent event) { System.out.println("监听器:" + this + "接收到业务事件，业务事件类型是[" + event.getBusinessEventType() + "] ## 业务事件附带的数据[" + event.getBusinessData() + "]"); } }
好了，全部的框架都完成了，那现在我们把上述模块完整的调用起来。
/** * @filename:Main.java * * Newland Co. Ltd. All rights reserved. * * @Description:主函数 * @author tangjie * @version 1.0 * */ package newlandframework.businessevent; public class Main { /** * @param args */ public static void main(String[] args) { // 注册监听器 BusinessEventManagement businessEventManagement = new BusinessEventManagement(); businessEventManagement.addBusinessEventListener("彩铃监听器",new ColorRingListener()); businessEventManagement.addBusinessEventListener("短信监听器",new SendSmsListener()); // 业务事件触发 BusinessEventNotify sender = new BusinessEventNotify(businessEventManagement); sender.notify(new BusinessEvent("彩铃监听器", "ReadBusinessEvent")); sender.notify(new BusinessEvent("短信监听器", "WriteBusinessEvent")); } }
彩铃监听器感兴趣的事件是读事件（ReadBusinessEvent），短信监听器感兴趣的事件是写事件（WriteBusinessEvent）。运行起来之后，发现果然组织的很好。当然有人会说，上面的情况JDK里面已经有现成的类（java.util.EventObject、java.util.EventListener）支持了。那下面我们就根据上面的例子，利用Spring框架来模拟一下事件模型是如何更优雅的应用的。
在Spring里面，所有事件的基类是ApplicationEvent，那我们从这个类派生一下，重新定义一下我们的业务事件。代码如下
/** * @filename:BusinessEvent.java * * Newland Co. Ltd. All rights reserved. * * @Description:业务事件定义 * @author tangjie * @version 1.0 * */ package newlandframework.spring; import org.springframework.context.ApplicationEvent; public class BusinessEvent extends ApplicationEvent { // 某种具体的业务事件的数据内容 private Object businessData; // 某种具体的业务事件的事件类型 private String businessEventType; public BusinessEvent(String businessEventType, Object businessData) { super(businessEventType); this.businessEventType = businessEventType; this.businessData = businessData; } public Object getBusinessData() { return this.businessData; } public String getBusinessEventType() { return this.businessEventType; } }
同样的，事件的发送者也要进行一下调整，代码如下
/** * @filename:BusinessEventNotify.java * * Newland Co. Ltd. All rights reserved. * * @Description:业务事件发送者 * @author tangjie * @version 1.0 * */ package newlandframework.spring; import java.util.List; import newlandframework.spring.BusinessEvent; import org.springframework.beans.BeansException; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; public class BusinessEventNotify implements ApplicationContextAware { private List<String> businessListenerList; private ApplicationContext ctx; public void setBusinessListenerList(List<String> businessListenerList) {
this.businessListenerList = businessListenerList; } public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { this.ctx = applicationContext; } public void notify(BusinessEvent businessEvent) { if (businessListenerList.contains(businessEvent.getBusinessEventType())) { BusinessEvent event = new BusinessEvent( businessEvent.getBusinessEventType(), businessEvent.getBusinessData()); ctx.publishEvent(event); return; } } }
下面我们就来注册一下Spring方式的短信、彩铃监听器：
/** * @filename:SendSmsListener.java * * Newland Co. Ltd. All rights reserved. * * @Description:短信消息监听器 * @author tangjie * @version 1.0 * */ package newlandframework.spring; import org.springframework.context.ApplicationEvent; import org.springframework.context.ApplicationListener; public class SendSmsListener implements ApplicationListener { final String strKey = "SMS"; public void onApplicationEvent(ApplicationEvent event) { // 这里你可以截取感兴趣的实际类型 if (event instanceof BusinessEvent) { BusinessEvent businessEvent = (BusinessEvent) event; if (businessEvent.getBusinessEventType().toUpperCase().contains(strKey)) { System.out.println("监听器:" + this + "接收到业务事件，业务事件类型是[" + businessEvent.getBusinessEventType() + "] ## 业务事件附带的数据[" + businessEvent.getBusinessData() + "]"); } } } }
/** * @filename:ColorRingListener.java * * Newland Co. Ltd. All rights reserved. * * @Description:彩铃消息监听器 * @author tangjie * @version 1.0 * */ package newlandframework.spring; import org.springframework.context.ApplicationEvent; import org.springframework.context.ApplicationListener; public class ColorRingListener implements ApplicationListener { public void onApplicationEvent(ApplicationEvent event) { if (event instanceof BusinessEvent) { BusinessEvent businessEvent = (BusinessEvent) event; System.out.println("监听器:" + this + "接收到业务事件，业务事件类型是[" + businessEvent.getBusinessEventType() + "] ## 业务事件附带的数据[" + businessEvent.getBusinessData() + "]"); } } }
最后我们编写一下Spring的依赖注入的配置文件spring-event.xml，当然事件的监听器也是在这里面依赖注入实现自动装配的。
<?xml version="1.0" encoding="GBK"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd" default-autowire="byName"> <bean id="smsListener" class="newlandframework.spring.SendSmsListener" /> <bean id="ringListener" class="newlandframework.spring.ColorRingListener" /> <bean id="event" class="newlandframework.spring.BusinessEventNotify"> <property name="businessListenerList"> <list> <value>DealColorRing</value> <value>DealSms</value> </list> </property> </bean> </beans>
一切准备就绪，现在我们把上面Spring方式实现的事件模型，完整的串起来，代码如下：
/** * @filename:Main.java * * Newland Co. Ltd. All rights reserved. * * @Description:主函数 * @author tangjie * @version 1.0 * */ package newlandframework.spring; import newlandframework.spring.BusinessEvent; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Main { public static void main(String[] args) { ApplicationContext ctx = new ClassPathXmlApplicationContext("newlandframework/spring/spring-event.xml"); BusinessEventNotify sender = (BusinessEventNotify) ctx.getBean("event"); sender.notify(new BusinessEvent("DealColorRing", "ReadBusinessEvent"));
sender.notify(new BusinessEvent("DealSms", "ReadBusinessEvent")); } }
运行的结果如下，非常完美，不是么？
