This works by defining a 'thing' on the server (in this blog we're creating a data store) to then allow the retrieval of objects from the server. This this information can then be used within your application to perform tasks (in this example it's using a data source to connect to a database).

JNDI basically bridges the J2EE components together and provides your applications the dynamic expansion. By allowing the application server to be responsible for the database connection allows your application to expand without scalable constraints or constant changes.

JNDI is fairly straightforward, initially you obtain a JNDI naming context, which is simply a connection to your application server, then you can use this connection to lookup a specific 'thing' (data source), then you use the connection to the application server to send over queries and the application server will send back an array of results (strings) of which you can use within your application.

In this blog, a java class is created to call the Weblogic data store, of which will create an initial context and the SQL scripts is sent to retrieve the information within a string array

Firstly, log into WLS and go to services -- data sources

Next, click create and provide a name. Then within the configuration tab, provide a JNDI Name. (in this example it's called jdbc/TestDataSource).

Within the connection pool, add in the URL, driver class name and the password for the user. The generator will place the information into the fields as highlighted in the screenshot.

Also, make sure you assign the data source to a specific target (in this example I've assigned the data source to the Admin server). This avoids the misleading exception error:

The Exception: javax.naming.NameNotFoundException: Unable to resolve 'jdbc.TestDataSource'. Resolved 'jdbc' [Root exception is javax.naming.NameNotFoundException:

Once that is setup, you're ready to create the java code to connect to the data source.

The code...

import java.io.*;
import java.sql.*;
import java.util.*;
import javax.naming.*;

public class testJNDI {
 static Connection connection = null;

 public static void main(String [] args) throws IOException, NamingException, SQLException{

  getSQLData(args);
}

 public static void getSQLData(String [] args) throws IOException, NamingException, SQLException{
  Statement st = null;
  ResultSet rs = null;

  try{
   FileInputStream fis = new FileInputStream(args[0]);
   Properties props = new Properties();
   props.load(fis);

   Hashtable env = new Hashtable();
   env.put(Context.INITIAL_CONTEXT_FACTORY,"weblogic.jndi.WLInitialContextFactory");
   env.put(Context.PROVIDER_URL,"t3://172.16.101.244:7100");

   Context context = new InitialContext(env);

   DataSource dataSource =(DataSource)context.lookup("jdbc/TestDataSource");

   connection = dataSource.getConnection();

   System.out.println("Connection to \"" + dataSource + "\" Established: " + connection.toString());

   st = connection.createStatement();
   String query = "SELECT * FROM RBACXSERVICE.GLOBALUSERS";
   rs = st.executeQuery(query);

   while(rs.next())
   {
    String userLogin = rs.getString("globaluserkey");
   System.out.println(userLogin);
  }

  }catch(Exception e){
   System.out.println("Exception: "+e);
  }finally{

   connection.close();
  }
 }
}

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