Client.java

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;
import java.sql.Connection;

...

String datasource = "FNOSDS"
Context ctx = new InitialContext();
DataSource ds = (DataSource)ctx.lookup(datasource);
Connection dbConnection = ds.getConnection();

DatabaseContextFactory.java

import java.util.Hashtable;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.naming.spi.InitialContextFactory;
import javax.naming.spi.InitialContextFactoryBuilder;
import javax.sql.DataSource;

public class DatabaseContextFactory implements  InitialContextFactory, InitialContextFactoryBuilder 
{
	  static DatabaseContext context;
	
    public Context getInitialContext(Hashtable<?, ?> environment) throws NamingException
    {
    	if(context==null){
    		context = new DatabaseContext();
    	}
    	
        return context;
    }

    public InitialContextFactory createInitialContextFactory(Hashtable<?, ?> environment) throws NamingException
    {
        return new DatabaseContextFactory();
    }
    
    final class DatabaseContext extends InitialContext 
    {
    	DataSource datasource;
    	
        DatabaseContext() throws NamingException{ }

    @Override
		public void bind(String name, Object obj) throws NamingException 
		{
			if("FNOSDS".equals(name)){
				datasource = (DataSource)obj;
			}
			else{
				super.bind(name, obj);
			}
		}

		@Override
        public Object lookup(String name) throws NamingException
        {
			if("FNOSDS".equals(name)){
				return datasource;
			}
			
			return super.lookup(name);
        }        
    }
}

Main.java

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.spi.NamingManager;
import com.ibm.db2.jcc.DB2SimpleDataSource; // db2jcc.jar

...

DB2SimpleDataSource db2Source=new DB2SimpleDataSource();
db2Source.setServerName("url.host.com");
db2Source.setPortNumber(50000);
db2Source.setDatabaseName("FNOS");
db2Source.setDriverType(4);
db2Source.setDescription("Filenet DB2");
db2Source.setUser("db2admin");
db2Source.setPassword("db2admin");

NamingManager.setInitialContextFactoryBuilder(new DatabaseContextFactory());

Context ctx = new InitialContext();
ctx.bind("FNOSDS", db2Source);