从WAR自动运行线程

Question

Im having a war file which contains some jsp files. I have a thread in a separate java file which updates the database periodically and my jsp files will get data from the database on demand.

Now , I need the thread to start automatically from a war archive so that it can do the tasks periodically and the user can get updated results from the view component.

public class AttendanceThread {
    private long DEFAULT_SLEEP_TIME = 10000;// 10 seconds.
    private long MAX_SLEEP_TIME = 30000;// 30 seconds.
    private int shift;

    public void MonitorAtttendance() {
        final UpdateAttendance updateObject = new UpdateAttendance();
        Runnable attThread = new Runnable() {
            @Override
            public void run() {
                try {
                          // logic to calculate the current shift time

                            updateObject.CheckEmpAttendance(shift);
                            updateObject.resetUpdatedAttendance(shift);
                            Thread.sleep(MAX_SLEEP_TIME);
                        } else {
                            Thread.sleep(DEFAULT_SLEEP_TIME);
                        }
                    }// end of while (true)
                } catch (Exception e) {
                                        }
            }// end of run()
        }; // end of attThread definition
        Thread t = new Thread(attThread);
        t.setName(this.getClass().getSimpleName());
        t.start();
    } 

    public static void main(String args[]) {
        // logger.log(Level.INFO, "Monitor Atttendance");
        AttendanceThread ma = new AttendanceThread();
        ma.MonitorAtttendance();
    }
}

Currently for test purposes, im running this java file separetely so that the thread can run and i can get updated results in my JSP files.

Is there any way we can start the thread from the WAR itself or automatically when the web server starts. Any help will be much appreciated. :)

Answer 1

From your war file, you could do the same from contextListener like:

public class ContextListenerExample implements ServletContextListener {
    public void contextInitialized(ServletContextEvent e){
        ServletContextcntxt = e.getServletContext();
        //start your thread here

And define this listener in your web.xml, so it starts when your web application starts as below:

<listener>
    <listener-class>ContextListenerExample</listener-class>
</listener>