Close connection to database correctly

Waylander · **Joined:** Tue Jan 31, 2012 3:23 pm **Posts:** 7

Hi Guys,

I'm currently experiencing an interesting problem.

My Situation:
- I am currently developing a web service (if you want further details, I'm using VAADIN for programming with JAVA)
- My database behind is java derby
- I am using hibernate (Of course :) )
- I'm currently deploying it on Tomcat v7.0

My Problem:
- When I change something in my code (doesn't matter what), the server should reload it without the need of being restarted
- The server reloads the application successfull, but if I try to click on something (so after the reloading) I get an error

Error Message:

Quote:

Cause: org.hibernate.exception.GenericJDBCException: Could not open connection] with root cause
ERROR XSDB6: Another instance of Derby may have already booted the database C:\HTML-Ausgabe\database\DocumentDB.
at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
...

My Thoughts on this
It seems that somehow on the reloading process the connection/context to hibernate doesnt get destroyed/closed and so the error occures when the server tries to reconnect to the database

My Code
I have a class, called Hibernate Listener:

Code:

public class HibernateListener implements ServletContextListener {

    public void contextInitialized(ServletContextEvent event) {
        HibernateUtil.getSessionFactory(); // Just call the static initializer of that class    
    }
    
    public void contextDestroyed(ServletContextEvent event) {
        HibernateUtil.getSessionFactory().close(); // Free all resources
    }
}

My hibernate.cfg.xml:

Code:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
      "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
      "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
   <session-factory>
      <property name="hibernate.connection.driver_class">org.apache.derby.jdbc.EmbeddedDriver</property>
      <property name="hibernate.connection.url">jdbc:derby:C:\HTML-Ausgabe\database\DocumentDB;create=true</property>
      <property name="hibernate.dialect">org.hibernate.dialect.DerbyDialect</property>
      <property name="hibernate.current_session_context_class">thread</property>
      <property name="hibernate.hbm2ddl.auto">create-drop</property>
      <property name="hibernate.show_sql">true</property>
      
      <mapping class="view.model.database.User"/>
      <mapping class="view.model.database.Document"/>
      <mapping class="view.model.database.Version"/>
      <mapping class="view.model.database.VersionData"/>
   </session-factory>
</hibernate-configuration>

My (VAADIN) web.xml, in which I added a "listener" for the upper shown HibernateListener (check the bold text below):

Code:

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
   <display-name>Bachelorprojekt</display-name>
   <context-param>
      <description>Vaadin production mode</description>
      <param-name>productionMode</param-name>
      <param-value>false</param-value>
   </context-param>
   <servlet>
      <servlet-name>Bachelorprojekt Application</servlet-name>
      <servlet-class>com.vaadin.terminal.gwt.server.ApplicationServlet</servlet-class>
      <init-param>
         <description>Vaadin application class to start</description>
         <param-name>application</param-name>
         <param-value>view.view.WebsiteFrame</param-value>
      </init-param>
   </servlet>
   <servlet-mapping>
      <servlet-name>Bachelorprojekt Application</servlet-name>
      <url-pattern>/*</url-pattern>
   </servlet-mapping>
   
[b]   <listener>
      <listener-class>view.model.database.HibernateListener</listener-class>
   </listener>[/b]
   <welcome-file-list>
      <welcome-file>index.html</welcome-file>
      <welcome-file>index.htm</welcome-file>
      <welcome-file>index.jsp</welcome-file>
      <welcome-file>default.html</welcome-file>
      <welcome-file>default.htm</welcome-file>
      <welcome-file>default.jsp</welcome-file>
   </welcome-file-list>
</web-app>

If anyone of you could help me somehow, I would be really happy. Currently I dont know what to change to stop this error happening. And, of course, I cant always restart the whole server later when my application is on the internet, if I change one line of code.

Thanks a lot for every answer and thought that you're sharing with me.

Waylander · **Joined:** Tue Jan 31, 2012 3:23 pm **Posts:** 7

Can anyone help me please here, this is a serious issue for me at the moment :(

Waylander · **Joined:** Tue Jan 31, 2012 3:23 pm **Posts:** 7

Can anyone help me here?

Or did someone experience something similiar while using a database?

I guess if you use a database you also don't restart your whole server from scratch if you changed one line of code, do you?

Thanks a lot for every post

sanne.grinovero · **Posted:** Fri Mar 30, 2012 7:36 pm

You're closing the SessionFactory, in _contextDestroyed_ but you're not restarting it in _contextInitialized_ as the static initializer triggers only the first time.

Don't use HibernateUtil.