databasemanager.java

报表设计软件,很好的

/**
 * ========================================
 * JFreeReport : a free Java report library
 * ========================================
 *
 * Project Info:  http://www.jfree.org/jfreereport/index.html
 * Project Lead:  Thomas Morgner ([e-mail]);
 *
 * (C) Copyright 2000-2003, by Simba Management Limited and Contributors.
 *
 * This library is free software; you can redistribute it and/or modify it under the terms
 * of the GNU Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * ------------------------------
 * DatabaseManager.java
 * ------------------------------
 * (C)opyright 2003, by Thomas Morgner and Contributors.
 *
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Simba Management Limited);
 *
 * $Id: DatabaseManager.java,v 1.2 2004/04/20 18:54:42 taqua Exp $
 *
 * Changes
 * -------------------------
 * 27.09.2003 : Initial version
 *
 */

package org.jfree.designer.db;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import javax.swing.table.TableModel;

import org.jfree.report.util.Log;

public final class DatabaseManager
{
  private final ArrayList dbConnectionDefinitions;
  private ConnectionEntry currentEntry;
  private Connection connection;
  private TableModel lastQueryResult;


  public DatabaseManager ()
  {
    dbConnectionDefinitions = new ArrayList();
  }

  public final void addConnection (final ConnectionEntry ce)
  {
    if (ce == null)
    {
      throw new NullPointerException();
    }
    if (dbConnectionDefinitions.contains(ce) == false)
    {
      dbConnectionDefinitions.add(ce);
    }
  }

  public final boolean removeConnection (final ConnectionEntry ce)
  {
    if (ce == null)
    {
      throw new NullPointerException();
    }
    if (currentEntry.equals(ce))
    {
      setCurrentEntry(null);
    }
    return dbConnectionDefinitions.remove(ce);
  }

  public final Enumeration getDBConnections ()
  {
    return Collections.enumeration(dbConnectionDefinitions);
  }

  public final ConnectionEntry getCurrentEntry ()
  {
    return currentEntry;
  }

  public final void setCurrentEntry (final ConnectionEntry currentEntry)
  {
    if (this.currentEntry != null)
    {
      if (currentEntry.equals(this.currentEntry))
      {
        // do nothing if current entry did not change
        return;
      }

      if (connection != null)
      {
        try
        {
          if (connection.isClosed() == false)
          {
            connection.close();
          }
        }
        catch (SQLException e)
        {
          Log.debug("Failed to close connection.");
        }
      }
    }
    this.connection = null;
    this.currentEntry = currentEntry;
  }

  public final Connection getConnection ()
          throws SQLException
  {
    if (this.connection != null)
    {
      if (this.connection.isClosed() == false)
      {
        return this.connection;
      }
    }
    this.connection = currentEntry.createConnection();
    return connection;
  }

  public final TableModel getLastQueryResult ()
  {
    return lastQueryResult;
  }

  public final void setLastQueryResult (final TableModel lastQueryResult)
  {
    this.lastQueryResult = lastQueryResult;
  }
}