Quickstart Servlet Problem

kenlouie · **Joined:** Tue Aug 03, 2004 1:27 am **Posts:** 10

I have a problem with compiling the servlet I created from the quickstart.

Here is my simple servlet code:

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;

import java.util.ArrayList;
import java.util.Date;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;

/** Simple servlet used to test server.
* <P>
* Taken from Core Servlets and JavaServer Pages 2nd Edition
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2003 Marty Hall; may be freely used or adapted.
*/

public class HelloServlet1a extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String docType =
"<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 " +
"Transitional//EN\">\n";
out.println(docType +
"<HTML>\n" +
"<HEAD><TITLE>Hello</TITLE></HEAD>\n" +
"<BODY BGCOLOR=\"#FDF5E6\">\n" +
"<H1>Hello</H1>\n" +
"</BODY></HTML>");

try {
Session session = HibernateUtil.currentSession();

Transaction tx= session.beginTransaction();

Cat princess = new Cat();
princess.setName("Princess");
princess.setSex('F');
princess.setWeight(7.4f);

session.save(princess);
tx.commit();

HibernateUtil.closeSession();

}

catch (HibernateException e1) {
e1.printStackTrace();
}
}
}

The rest of the xml files and everything else I copied directly from the quickstart.

Here is part of the error message that is seen when I do: http://localhost:8080/quickstart/servlet/HelloServlet1a

exception

javax.servlet.ServletException: Invoker service() exception
org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServlet.java:477)
org.apache.catalina.servlets.InvokerServlet.doGet(InvokerServlet.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)

root cause

java.lang.NoClassDefFoundError
HelloServlet1a.doGet(HelloServlet1a.java:39)
javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServlet.java:419)
org.apache.catalina.servlets.InvokerServlet.doGet(InvokerServlet.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)

Is this a problem with my database pool connections? Any help would be appreciated like identifying the problem and telling how to fix it.

Thank you very much,
Kenneth

christian · **Posted:** Tue Aug 03, 2004 5:45 am

Use this in HibernateUtil:

Code:

    static {
        try {
            // Create the SessionFactory
            sessionFactory = new Configuration().configure().buildSessionFactory();
        } catch (Throwable ex) {
            log.error("Initial SessionFactory creation failed.", ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

kenlouie · **Joined:** Tue Aug 03, 2004 1:27 am **Posts:** 10

Okay so I replaced in my HibernateUtil code with this code:

static {
try {
// Create the SessionFactory
sessionFactory = new Configuration().configure().buildSessionFactory();
} catch (Throwable ex) {
ex.printStackTrace();
throw new ExceptionInInitializerError(ex);
}
}

Heh I didn't put the log.error() line but I figured printStackTrace was the same thing.

Now I got the same error message I got before like the exception part is the same. But under the root cause section the first line is different cuz it printed an error in the HibernateUtil code now as you can see, though the rest of the lines are the same:

exception

javax.servlet.ServletException: Invoker service() exception
org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServlet.java:477)
org.apache.catalina.servlets.InvokerServlet.doGet(InvokerServlet.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)

root cause

java.lang.ExceptionInInitializerError
HibernateUtil.<clinit>(HibernateUtil.java:14)
HelloServlet1a.doGet(HelloServlet1a.java:39)
javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServlet.java:419)
org.apache.catalina.servlets.InvokerServlet.doGet(InvokerServlet.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)

So do you have any idea what the problem is now that there is a new error message in HibernateUtil? I appreciate all help.

Thank you very much,
Kenneth

michael · **Posted:** Tue Aug 03, 2004 3:16 pm

You need the root cause for the java.lang.ExceptionInInitializerError - catch and log it in your servlet or replace throw new ExceptionInInitializerError(ex); with throw new ExceptionInInitializerError(ex.getMessage());

PS: I hate that stupid Java 1.4. Exception nesting

kenlouie · **Joined:** Tue Aug 03, 2004 1:27 am **Posts:** 10

Okay, here is what I added:

In my servlet HelloServlet1a I added this code on top:

import net.sf.hibernate.exception.NestableException;

I also added a catch for the NestableException at the end:

catch (NestableException ne) {
out.println("NestableException: " + ne.getMessage());
ne.printStackTrace(out);
}

Though the above code I don't think made much of a difference. I also added your suggestion of ex.getMessage() so now my HibernateUtil Code has this:

static {
try {
// Create the SessionFactory
sessionFactory = new Configuration().configure().buildSessionFactory();
} catch (Throwable ex) {
ex.printStackTrace();
throw new ExceptionInInitializerError(ex.getMessage());
}
}

When I do my: http://localhost:8080/quickstart/servlet/HelloServlet1a
There is a slight change in the error message for the root cause. It says error reading resource: Cat.hbm.xml . Here is the error message. It looks the same except for that line:

exception

javax.servlet.ServletException: Invoker service() exception
org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServlet.java:477)
org.apache.catalina.servlets.InvokerServlet.doGet(InvokerServlet.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)

root cause

java.lang.ExceptionInInitializerError: Error reading resource: Cat.hbm.xml
HibernateUtil.<clinit>(HibernateUtil.java:14)
HelloServlet1a.doGet(HelloServlet1a.java:41)
javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServlet.java:419)
org.apache.catalina.servlets.InvokerServlet.doGet(InvokerServlet.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)

So for reference here is my Cat.hbm.xml code though I copied it from the quickstart:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>

<class name="net.sf.hibernate.examples.quickstart.Cat" table="CAT">


<id name="id" type="string" unsaved-value="null" >
<column name="CAT_ID" sql-type="char(32)" not-null="true"/>
<generator class="uuid.hex"/>
</id>


<property name="name">
<column name="NAME" length="16" not-null="true"/>
</property>

<property name="sex"/>

<property name="weight"/>

</class>

</hibernate-mapping>

Any more suggestions? If you want me to include my Tomcat/conf/server.xml code or the hibernate.properties file or the hibernate.cfg.xml code as well I could include it in my next reply. I am using MySQL with no password, though I could put one in, but I don't think it makes much of a difference.

Thank you very much,
Kenneth Louie

christian · **Posted:** Tue Aug 03, 2004 8:15 pm

You will never find the root cause of this issue if you don't log the Throwable in the static initializer properly. This is usually a no-brainer, and I can't tell you why it doesn't work for you.

kenlouie · **Joined:** Tue Aug 03, 2004 1:27 am **Posts:** 10

It works, at least like that first part of the Cat stuff. I will probably have questions later on too. Thanx for replying

kenlouie · **Joined:** Tue Aug 03, 2004 1:27 am **Posts:** 10

Actually I have another question. I read somewhere that in MySQL the default storage engine is MyISAM. I heard that MyISAM does not support transactions. However, when I used my servlet that had the code for Transactions like:
try {
Session session = HibernateUtil.currentSession();

Transaction tx= session.beginTransaction();

Cat princess = new Cat();
princess.setName("Princess");
princess.setSex('F');
princess.setWeight(7.4f);

session.save(princess);
tx.commit();

HibernateUtil.closeSession();

}

So was this a fluke my servlet worked? If so, do I need code in my servlet to specify like that I should use the InnoDB storage engine? To change storage engines is all I need to do is to put ALTER Table in my mysql command lines, and I don't have to use any java code in my servlet right?

Thank you,
Kenneth Louie

kenlouie · **Joined:** Tue Aug 03, 2004 1:27 am **Posts:** 10

I believe that MySQL 4.0.2d i thnik uses MyISAM as the default. Please correct me if I'm wrong. My above question still applies though and I would appreciate an answer very much.

Thank you,
Kenneth Louie