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我在Esper中做了一个基于长度窗口的程序。但是当窗口已满时,以前的事件应该成为一个旧事件。当我试图在updateListener中打印那个旧事件时,我每次都变空。如何在esper中获得旧事件?
EPServiceProvider sp = EPServiceProviderManager.getDefaultProvider();
String qry = "select count(*) from com.bizruntime.Student.win:length(2)";
EPStatement statement = sp.getEPAdministrator().createEPL(qry);
MyListener listener = new MyListener();
statement.addListener(listener);
Student student1 = new Student(44,"xyz");
Student student2= new Student(45,"pqr");
Student student3 = new Student(43,"stu");
Student student4 = new Student(41,"abc");
sp.getEPRuntime().sendEvent(student1);
sp.getEPRuntime().sendEvent(student2);
sp.getEPRuntime().sendEvent(student3);
sp.getEPRuntime().sendEvent(student4);
这是监听器类:
public void update(EventBean[] newEvent, EventBean[] oldEvent) {
EventBean event = newEvent[0];
System.out.println(oldEvent);
System.out.println("Student Name :"+event.get("count(*)"));
}
感谢您的帮助。 – Santanu