How can I Load a class while startup tomcat Server

Question

I would like to load java class file that contain db related function. How can I load that java file while starting the tomcat server

have you tried using a singleton model for your db connection?? or static blocks?? what exactly is you issue with the thing you are trying to achieve?? — Abhishek, Oct 05 '16 at 12:46
Same way in which you refer to any other class file - you just refer to it and the JVM will load it when necessary. — Erwin Bolwidt, Oct 05 '16 at 12:46
I am using Quartz scheduler to schedule jobs.Once if we stop server,quartz related data will be gone. If I start the server again i need to get the job details from db and supply to scheduler method of submitted job details — sathish kumar balu, Oct 05 '16 at 12:48
Totally reading between the lines here .. but i think you mean, How do you cange Quartz to use a JDBC store from In memory http://stackoverflow.com/questions/13633404/quartz-scheduler-what-is-the-diff-between-ram-and-jdbc-job-store — Kenneth Clark, Oct 05 '16 at 12:54
Set up Quartz to use a database. For example, using this help page here: http://teknosrc.com/how-setup-quartz-scheduler-server-with-mysql-database/ — Erwin Bolwidt, Oct 05 '16 at 12:59
public class StartupInitializer { public void init() { } } @Erwin Bolwidt — sathish kumar balu, Oct 05 '16 at 13:20

score 1 · Accepted Answer · answered Oct 05 '16 at 12:51

1

you can use servlet for that as below, define into web.xml

<servlet>
   <servlet-name>YourServletName</servlet-name>
   <servlet-class>com.abc.xyz.YourServletClassName</servlet-class>
   <load-on-startup>1</load-on-startup>
</servlet>

in YourServletClassName.java file you can write your code.

Hope it helps you.

answered Oct 05 '16 at 12:51

PSabuwala

155
1
9

Did you ask about check authorization (spring-security) before your application load? – PSabuwala Oct 06 '16 at 08:44
Actually i didn't get, What is the link between your actual question and login authorization, Please explain. – PSabuwala Oct 06 '16 at 13:49
This is a pre-2001 solution. A generic solution for this would use a java.servlet.ServletContextListener. However it seems that the OP really needs to configure Quartz to do his dirty work instead. – Steve C Oct 07 '16 at 16:14

Yuriy N. · Answer 2 · 2021-04-04T12:20:59.070

The answer by Psabuwala is correct but not complete. Code that will run on startup should be placed in the init method of the servlet.

Web.xml:

...
<servlet>
    <servlet-name>mainServlet</servlet-name>
    <servlet-class>example.com.MainServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>
...

MainServlet.java:

public class MainServlet extends HttpServlet
{

    public void init() throws ServletException
    {
        DataLoader dataLoader = new DataLoader();
        dataLoader.load();
    }
    ... 
}

How can I Load a class while startup tomcat Server

2 Answers2