Question

Warning: New to Java

I have a simple Netbeans project – I wanted to just learn about interacting with DB’s coming from php I thought I would have a go with a local one running on my computer.

Lots of the examples out there say to use the InitialContext() object to refer to the database resource.

After following the examples I get the following exception – Lots of Google stuff points to some .xml file – which I have no idea about or even where it exists in the Netbeans project? I’m not using a Webserver at this time so not Tomcat or anything like that, just local Java program to do this, I suspect this might be the problem. Could anyone shed some light on this?

Exception thrown javax.naming.NoInitialContextException: Need to specify class name in environment or system property, or as an applet parameter, or in an application resource file:  java.naming.


package learningjava;
import com.mysql.jdbc.jdbc2.optional.*;
import com.mysql.jdbc.Driver;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.naming.*;



public class LearningJava {

    public static void main(String[] args) {

       MysqlDataSource test_db = new MysqlDataSource(); 

       test_db.setServerName("localhost");
       test_db.setDatabaseName("dev");

       try {

            InitialContext test_db_context = new InitialContext();
            test_db_context.bind("jcdb/testdb", test_db);
            MysqlDataSource test_db_datasource = (MysqlDataSource)test_db_context.lookup("testdb");

       } catch (NamingException e) {

           System.out.println("Exception thrown " + e);

       }
        try {

            test_db.getConnection("root","password");

        } catch (SQLException e) {

             System.out.println("Exception thrown " + e);

        }


    }    

}

Answer 1

In general you should understand that JNDI should have a server. In a code snippet you’ve provided you’re using a _CLIENT_SIDE_ part of JNDI technology when you’re doing your lookup. There should be a JNDI server that should be accessible from your local client connection.
Once configured properly, the call to lookup should issue a connection with JNDI server and provide a way to obtain/bind resources to that server.

How to configure JNDI properly?

Usually you should supply a properties file that will contain a host name of this server, a port + some implementation specific information.

JNDI server is usually already provided when you’re using application server (like JBoss or Web Sphere).
I think this is the root of misunderstanding here.

Hope, this helps