import java.sql.*;

public class TestDBOracle {

  public static void main(String[] args)
      throws ClassNotFoundException, SQLException
  {
    Class.forName("oracle.jdbc.driver.OracleDriver");
    //
    // or
    // DriverManager.registerDriver
    //        (new oracle.jdbc.driver.OracleDriver());

        String url = "jdbc:oracle:thin:@//server.local:1521/prod";
    //               jdbc:oracle:thin:@//host:port/service
    // or
    // String url = "jdbc:oracle:thin:@server.local:1521:prodsid";
    //               jdbc:oracle:thin:@host:port:SID
    //
    //  SID  - System ID of the Oracle server database instance.
    //         By default, Oracle Database 10g Express Edition
    //         creates one database instance called XE.
    //         ex : String url = "jdbc:oracle:thin:@myhost:1521:xe";



    Connection conn =
         DriverManager.getConnection(url,"scott","tiger");

    conn.setAutoCommit(false);
    Statement stmt = conn.createStatement();
    ResultSet rset =
         stmt.executeQuery("select BANNER from SYS.V_$VERSION");
    while (rset.next()) {
         System.out.println (rset.getString(1));
    }
    stmt.close();
    System.out.println ("Ok.");
  }
}

XE =
 (DESCRIPTION =
   (ADDRESS = (PROTOCOL = TCP)(HOST = myhost)(PORT = 1521))
   (CONNECT_DATA =
     (SERVER = DEDICATED)
     (SERVICE_NAME = XE)
   )
 )

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import oracle.jdbc.OracleDriver;

public class TestOra {
    public TestOra() {
        System.setProperty("oracle.net.tns_admin","\\\\myserver\\TNSNAMES_DIR");
        // or
        //  java.exe -Doracle.net.tns_admin=\\myserver\TNSNAMES_DIR TestOra ...
        //
    }

    public void doit () throws SQLException {
        String usr = "scott";
        String pwd = "tiger";
        String url = "jdbc:oracle:thin:@MYORCL";

        DriverManager.registerDriver(new OracleDriver());
        Connection conn = DriverManager.getConnection(url,usr,pwd);

        String sql = "select {fn now()} from dual" ;
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery(sql);
        while (rs.next())
            System.out.println("results: " + rs.getString(1));
        conn.close();
    }

    public static void main(String[] args){
        TestOra test = new TestOra();
        try {
            test.doit();
            System.out.println("Done..");
        }
        catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

/*

  \\myserver\TNSNAMES_DIR\tnsnames.ora


  MYORCL =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = orcltest.local)(PORT = 1521))
    )
    (CONNECT_DATA = (SERVICE_NAME = orcl)(INSTANCE_ROLE=ANY))
  )

 */