Metacat

/**

 *  '$RCSfile$'

 *    Purpose: An adapter class for PostgreSQL RDBMS.

 *  Copyright: 2000 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Jivka Bojilova

 *    Release: @release@

 *

 *   '$Author$'

 *     '$Date$'

 * '$Revision$'

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

package edu.ucsb.nceas.dbadapter;

import java.sql.*;

/**

 * The PostgreSQL db adapter implementation.

 */

public class PostgresqlAdapter extends AbstractDatabase {

  /**

   * The PostgreSQL unique ID /sequence generator

   * The name of the sequence used to generate the unique id 

   * is made from the name of the table that uses the id by 

   * appending "_id_seq" to it.

   * When record is inserted in the table and insert trigger gets

   * a nextval from that sequence, select currval of that sequence

   * can return the generated key in the same db connection.

   *

   * @param conn db connection in which the unique id was generated

   * @param tableName the name of table which unique id was generate

   * @exception SQLException any SQLException that can be thrown 

   *            during the db operation

   * @return return the generated unique id as a long type

   */

  public long getUniqueID(Connection conn, String tableName) 

                                         throws SQLException {

    long uniqueid = 0;

    Statement stmt = conn.createStatement();

    stmt.execute("SELECT currval('" + tableName + "_id_seq')");

    ResultSet rs = stmt.getResultSet();

    if ( rs.next() ) 

		{

      uniqueid = rs.getLong(1);

    }

    stmt.close();

    //System.out.println("Unique ID: " + uniqueid);    

    return uniqueid;

  }

  /**

   * The PostgreSQL function name that gets the current date 

   * and time from the database server

   *

   * @return return the current date and time function name: "now()"

   */

  public String getDateTimeFunction() {

    //System.out.println("The date and time function: " + "now()");    

		//to return just the date use now()::date

		//and for the time use now()::time

    return "now()";

  }

  /**

   * The PostgreSQL function name that is used to return non-NULL value

   *

   * @return return the non-NULL function name: "coalesce"

   */

  public String getIsNULLFunction() {

    return "coalesce";

  }

  /**

   * PostgreSQL's string delimiter character: single quote (')

   *

   * @return return the string delimiter: single quote (')

   */

  public String getStringDelimiter() {

    return "'";

  }

}

/**

 *  '$RCSfile$'

 *    Purpose: An adapter class for Oracle RDBMS.

 *  Copyright: 2000 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Jivka Bojilova

 *    Release: @release@

 *

 *   '$Author$'

 *     '$Date$'

 * '$Revision$'

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

package edu.ucsb.nceas.dbadapter;

import java.sql.*;

/**

 * The Oracle db adapter implementation.

 */

public class OracleAdapter extends AbstractDatabase {

  /**

   * The Oracle unique ID generator through use of sequences

   * The name of the sequence used to generate the unique id 

   * is made from the name of the table that uses the id by 

   * appending "_id_seq" to it.

   * When record is inserted in the table and insert trigger gets

   * a nextval from that sequence, select currval of that sequence

   * can return the generated key in the same db connection.

   *

   * @param conn db connection in which the unique id was generated

   * @param tableName the name of table which unique id was generate

   * @exception SQLException <br/> any SQLException that can be thrown 

   *            during the db operation

   * @return return the generated unique id as a long type

   */

  public long getUniqueID(Connection conn, String tableName) 

                                         throws SQLException {

    long uniqueid = 0;

    Statement stmt = conn.createStatement();

    stmt.execute("SELECT " + tableName + "_id_seq.currval FROM dual");

    ResultSet rs = stmt.getResultSet();

    if ( rs.next() ) {

      uniqueid = rs.getLong(1);

    }

    stmt.close();

    //System.out.println("Unique ID: " + uniqueid);    

    return uniqueid;

  }

  /**

   * The Oracle's function name that gets the current date and time

   * from the database server: "sysdate"

   *

   * @return return the current date and time function name: "sysdate"

   */

  public String getDateTimeFunction() {

    //System.out.println("The date and time function: " + "sysdate");    

    return "sysdate";

  }

  /**

   * The Oracle's function name that is used to return non-NULL value

   *

   * @return return the non-NULL function name: "nvl"

   */

  public String getIsNULLFunction() {

    return "nvl";

  }

  /**

   * The Oracles's string delimiter character: single quote (')

   *

   * @return return the string delimiter: single quote (')

   */

  public String getStringDelimiter() {

    return "'";

  }

}

/**

 *  '$RCSfile$'

 *    Purpose: An adapter class for MS SQL Server RDBMS.

 *  Copyright: 2000 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Jivka Bojilova

 *    Release: @release@

 *

 *   '$Author$'

 *     '$Date$'

 * '$Revision$'

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

package edu.ucsb.nceas.dbadapter;

import java.sql.*;

/**

 * The MS SQL Server db adapter implementation.

 */

public class SqlserverAdapter extends AbstractDatabase {

  /**

   * The SQL Server unique ID generator through use of IDENTITY key

   * The IDENTITY key is a column in the table. When record is inserted

   * in the table, SELECT @@IDENTITY can return the key generated in

   * that IDENTITY column in the same db connection.

   * This is the only way to get unique id: let the SQL Server assign

   * a value in IDENTITY column and get it afterwards for use in the 

   * application.

   *

   * @param conn db connection in which to generate the unique id

   * @param tableName the name of table which unique id to generate

   * @exception SQLException <br/> any SQLException that can be thrown 

   *            during the db operation

   * @return return the generated unique id as a long type

   */

  public long getUniqueID(Connection conn, String tableName) 

                                         throws SQLException {

    long uniqueid = 0;

    Statement stmt = conn.createStatement();

    stmt.execute("SELECT @@IDENTITY");

    ResultSet rs = stmt.getResultSet();

    if ( rs.next() ) {

      uniqueid = rs.getLong(1);

    }

    stmt.close();

    //System.out.println("Unique ID: " + uniqueid);    

    return uniqueid;

  }

  /**

   * The SQL Server's function name that gets the current date and time

   * from the database server: "getdate()"

   *

   * @return return the current date and time function name: "getdate()"

   */

  public String getDateTimeFunction() {

    //System.out.println("The date and time function: " + "getdate()");    

    return "getdate()";

  }

  /**

   * The SQL Server's function name that is used to return non-NULL value

   *

   * @return return the non-NULL function name: "isnull"

   */

  public String getIsNULLFunction() {

    return "isnull";

  }

  /**

   * The SQL Server's string delimiter character: single quote (')

   *

   * @return return the string delimiter: single quote (')

   */

  public String getStringDelimiter() {

    return "'";

  }

}

/**

 *  '$RCSfile$'

 *    Purpose: An abstract class that encapsulates access to any RDBMS.

 *             This allows to swap easily between databases without any

 *             modification to the application.

 *  Copyright: 2000 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Jivka Bojilova

 *    Release: @release@

 *

 *   '$Author$'

 *     '$Date$'

 * '$Revision$'

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

package edu.ucsb.nceas.dbadapter;

import java.sql.*;

import edu.ucsb.nceas.metacat.MetaCatUtil;

/**

 * Java offers uniform database access through the use of JDBC.

 * But many databases still use different SQL implementations and 

 * conventions. Thus this class offers extended programming interface

 * that all subclasses should implement to gain access to different

 * databases.

 *

 * To add a new database adapter class you must create a new class 

 * <dbname>Adapter that extends edu.ucsb.nceas.dbadapter.AbstarctDatabase

 * (where dbname is the name of the database or database driver you wish

 * to add to your application). AbstarctDatabase is an abstract class,

 * thus the subclasses need to implement the abstract methods.

 */

public abstract class AbstractDatabase {

  /**

   * Unique ID generator

   *

   * @param conn db connection in which the unique id was generated

   * @param tableName the table which unique id was generate

   * @exception SQLException <br/> any SQLException that can be thrown 

   *            during the db operation

   * @return return the generated unique id as a long type

   */

  public abstract long getUniqueID(Connection conn, String tableName) 

                                                  throws SQLException;

  /**

   * The function name that gets the current date and time

   * from the database server

   *

   * @return return the current date and time function name

   */

  public abstract String getDateTimeFunction();

  /**

   * The function name that is used to return non-NULL value

   *

   * @return return the non-NULL function name

   */

  public abstract String getIsNULLFunction();

  /**

   * The character that the specific database implementation uses to 

   * indicate string literals in SQL. This will usually be a single

   * qoute (').

   *

   * @return return the string delimiter

   */

  public abstract String getStringDelimiter();

  /**

   * Instantiate a class using the name of the class at runtime

   *

   * @param className the fully qualified name of the class to instantiate

   */

  static public Object createObject(String className) throws Exception {

    Object object = null;

    try {

      Class classDefinition = Class.forName(className);

      object = classDefinition.newInstance();

    } catch (InstantiationException e) {

      throw e;

    } catch (IllegalAccessException e) {

      throw e;

    } catch (ClassNotFoundException e) {

      throw e;

    }

    return object;

  }

  /**

   * the main routine used to test the dbadapter utility.

   */

  static public void main(String[] args) {

    // Determine our db adapter class and

    // create an instance of that class

    try {

      MetaCatUtil util = new MetaCatUtil();

      String dbAdapter = util.getOption("dbAdapter");

      AbstractDatabase dbAdapterObj = (AbstractDatabase)createObject(dbAdapter);

      // test if they work correctly

      String date = dbAdapterObj.getDateTimeFunction();

      Connection conn = util.openDBConnection();

      long uniqueid = dbAdapterObj.getUniqueID(conn, "xml_catalog");

      conn.close();

      conn = null;

    } catch (Exception e) {

      System.out.println(e);

    }

  }

}