esper（4-3）-Non-Overlapping Context

语法

create context context_name 
start start_condition 
end end_condition

如：

// 9点到17点此context才可用（以引擎的时间为准）。如果事件进入的事件不在此范围内，则不受该context影响
create context NineToFive start (0, 9, *, *, *) end (0, 17, *, *, *)

 

例子

import com.espertech.esper.client.*;/*** @author yaoyuan2* @date 2019/3/26*/
public class NoOverLappingContextTest {public static void main(String[] args) {EPServiceProvider epService = EPServiceProviderManager.getDefaultProvider();EPAdministrator admin = epService.getEPAdministrator();EPRuntime runtime = epService.getEPRuntime();String start = StartEvent.class.getName();String end = EndEvent.class.getName();String other = OtherEvent.class.getName();// 以StartEvent事件作为开始条件，EndEvent事件作为结束条件String epl1 = "create context NoOverLapping start " + start + " end " + end;String epl2 = "context NoOverLapping select * from " + other;admin.createEPL(epl1);EPStatement state = admin.createEPL(epl2);state.addListener(new UpdateListener() {@Overridepublic void update(EventBean[] newEvents, EventBean[] oldEvents) {if (newEvents != null) {EventBean event = newEvents[0];System.out.println("Class:" + event.getUnderlying().getClass().getName() + ", id:" + event.get("id"));}}});StartEvent s = new StartEvent();System.out.println("sendEvent: StartEvent");runtime.sendEvent(s);OtherEvent o = new OtherEvent();o.setId(2);System.out.println("sendEvent: OtherEvent");runtime.sendEvent(o);EndEvent e = new EndEvent();System.out.println("sendEvent: EndEvent");runtime.sendEvent(e);OtherEvent o2 = new OtherEvent();o2.setId(4);System.out.println("sendEvent: OtherEvent");runtime.sendEvent(o2);}
}
class StartEvent
{
}class EndEvent
{
}
class OtherEvent
{private int id;public int getId(){return id;}public void setId(int id){this.id = id;}
}

输出

sendEvent: StartEvent
sendEvent: OtherEvent
Class:com.ebc.NoOverLappingContext.OtherEvent, id:2
sendEvent: EndEvent
sendEvent: OtherEvent

由此看出，在NoOverLapping这个Context下监控OtherEvent，必须是在StartEvent被触发才能监控到，所以在EndEvent发送后，再发送一个OtherEvent是不会触发Listener的。