tomcat auto start servlet [duplicate]

Answer 1

Use the load-on-startup in WEB-INF/web.xml. In Netbeans it is in the Servlets tab, the item "Startup order".

<servlet>
    <servlet-name>Hl7Servlet</servlet-name>
    <servlet-class>nl.vandenzen.Hl7Servlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>

Answer 2

you could use the servlet context listener. More specifically you could start your thread in the contextInitialized method:

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class MyListener implements ServletContextListener {

    public void contextInitialized(ServletContextEvent sce) {
         // start the thread
    }

    public void contextDestroyed(ServletContextEvent sce) {
         // stop the thread
    }
}

then add:

<listener>
    <description>ServletContextListener</description>
    <listener-class>MyListener</listener-class>
</listener>

in you web.xml

Answer 3

Another alternative would be to use the Quartz Scheduler.

Quartz is a full-featured, open source job scheduling system that can be integrated with, or used along side virtually any J2EE or J2SE application - from the smallest stand-alone application to the largest e-commerce system. Quartz can be used to create simple or complex schedules for executing tens, hundreds, or even tens-of-thousands of jobs; jobs whose tasks are defined as standard Java components or EJBs. The Quartz Scheduler includes many enterprise-class features, such as JTA transactions and clustering.

It's very easy to use, and it's entire reason for existing is to schedule jobs. Which sounds like what you wanting to do.