scrollableresultsettablemodel.java

Java的Web报表库

/**
 * ========================================
 * JFreeReport : a free Java report library
 * ========================================
 *
 * Project Info:  http://www.jfree.org/jfreereport/index.html
 * Project Lead:  Thomas Morgner;
 *
 * (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.
 *
 * ----------------------------------
 * ScrollableResultSetTableModel.java
 * ----------------------------------
 * (C)opyright 2002, 2003, by Thomas Morgner.
 *
 * $Id: ScrollableResultSetTableModel.java,v 1.8.2.1 2003/08/24 14:18:11 taqua Exp $
 *
 * Changes
 * -------
 * 25-Apr-2002 : Initial version
 * 09-Jun-2002 : Implements the CloseableTableModel interface
 * 09-Dec-2002 : Updated error messages.
 */
package com.jrefinery.report.tablemodel;

import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import javax.swing.table.AbstractTableModel;

import com.jrefinery.report.util.CloseableTableModel;
import com.jrefinery.report.util.Log;

/**
 * A tableModel which is backed up by a java.sql.ResultSet. Use this to directly feed your
 * database data into JFreeReport. If you have trouble using this TableModel and you have
 * either enough memory or your query result is not huge, you may want to use
 * <code>ResultSetTableModelFactory.generateDefaultTableModel (ResultSet rs)</code>.
 * That implementation will read all data from the given ResultSet and keep that data in
 * memory.
 * <p>
 * Use the close() function to close the ResultSet contained in this model.
 *
 * @author Thomas Morgner
 */
public class ScrollableResultSetTableModel extends AbstractTableModel implements CloseableTableModel
{
  /**
   * The scrollable ResultSet source.
   */
  private ResultSet resultset;

  /**
   * The ResultSetMetaData object for this result set.
   */
  private ResultSetMetaData dbmd;

  /**
   * The number of rows in the result set.
   */
  private int rowCount;

  /**
   * Constructs the model.
   *
   * @param resultset  the result set.
   *
   * @throws SQLException if there is a problem with the result set.
   */
  public ScrollableResultSetTableModel(final ResultSet resultset) throws SQLException
  {
    if (resultset != null)
    {
      updateResultSet(resultset);
    }
    else
    {
      close();
    }
  }

  /**
   * Default constructor.
   */
  protected ScrollableResultSetTableModel()
  {
  }

  /**
   * Updates the result set in this model with the given ResultSet object.
   *
   * @param resultset the new result set.
   *
   * @throws SQLException if there is a problem with the result set.
   */
  public void updateResultSet(final ResultSet resultset) throws SQLException
  {
    if (this.resultset != null)
    {
      close();
    }

    this.resultset = resultset;
    this.dbmd = resultset.getMetaData();

    if (resultset.last())
    {
      rowCount = resultset.getRow();
    }
    else
    {
      rowCount = 0;
    }

    fireTableStructureChanged();
  }

  /**
   * Clears the model of the current result set. The resultset is closed.
   */
  public void close()
  {
    // Close the old result set if needed.
    if (resultset != null)
    {
      try
      {
        resultset.close();
      }
      catch (SQLException e)
      {
        // Just in case the JDBC driver can't close a result set twice.
        //  e.printStackTrace();
      }
    }
    resultset = null;
    dbmd = null;
    rowCount = 0;
    fireTableStructureChanged();
  }

  /**
   * Get a rowCount. This can be a very expensive operation on large
   * datasets. Returns -1 if the total amount of rows is not known to the result set.
   *
   * @return the row count.
   */
  public int getRowCount()
  {
    if (resultset == null)
    {
      return 0;
    }

    try
    {
      if (resultset.last())
      {
        rowCount = resultset.getRow();
        if (rowCount == -1)
        {
          rowCount = 0;
        }
      }
      else
      {
        rowCount = 0;
      }
    }
    catch (SQLException sqle)
    {
      //Log.debug ("GetRowCount failed, returning 0 rows", sqle);
      return 0;
    }
    return rowCount;
  }

  /**
   * Returns the number of columns in the ResultSet. Returns 0 if no result set is set
   * or the column count could not be retrieved.
   *
   * @return the column count.
   *
   * @see java.sql.ResultSetMetaData#getColumnCount()
   */
  public int getColumnCount()
  {
    if (resultset == null)
    {
      return 0;
    }

    if (dbmd != null)
    {
      try
      {
        return dbmd.getColumnCount();
      }
      catch (SQLException e)
      {
        //Log.debug ("GetColumnCount failed", e);
      }
    }
    return 0;
  }

  /**
   * Returns the columnLabel for the given column.
   *
   * @param column  the column index.
   *
   * @return the column name.
   *
   * @see java.sql.ResultSetMetaData#getColumnLabel(int)
   */
  public String getColumnName(final int column)
  {
    if (dbmd != null)
    {
      try
      {
        return dbmd.getColumnLabel(column + 1);
      }
      catch (SQLException e)
      {
        Log.info("ScrollableResultSetTableModel.getColumnName: SQLException.");
      }
    }
    return null;
  }

  /**
   * Returns the value of the specified row and the specified column from within the resultset.
   *
   * @param row  the row index.
   * @param column  the column index.
   *
   * @return the value.
   */
  public Object getValueAt(final int row, final int column)
  {
    if (resultset != null)
    {
      try
      {
        resultset.absolute(row + 1);
        return resultset.getObject(column + 1);
      }
      catch (SQLException e)
      {
        //Log.debug ("Query failed for [" + row + "," + column + "]", e);
      }
    }
    return null;
  }

  /**
   * Returns the class of the resultset column. Returns Object.class if an error occurred.
   *
   * @param column  the column index.
   *
   * @return the column class.
   */
  public Class getColumnClass(final int column)
  {
    if (dbmd != null)
    {
      try
      {
        return getClass().getClassLoader().loadClass(getColumnClassName(column));
      }
      catch (Exception e)
      {
        //Log.debug ("GetColumnClass failed for " + column, e);
      }
    }
    return Object.class;
  }


  /**
   * Returns the classname of the resultset column. Returns Object.class if an error occurred.
   *
   * @param column  the column index.
   *
   * @return the column class name.
   */
  public String getColumnClassName(final int column)
  {
    if (dbmd != null)
    {
      try
      {
        return mckoiDBFixClassName(dbmd.getColumnClassName(column + 1));
      }
      catch (SQLException e)
      {
        //Log.debug ("GetColumnClassName failed for " + column, e);
      }
    }
    return Object.class.getName();
  }

  /**
   * Just removes the word class from the start of the classname string
   * McKoiDB version 0.92 was not able to properly return classnames of
   * resultset elements.
   *
   * @param classname  the class name.
   *
   * @return the modified class name.
   */
  private String mckoiDBFixClassName(final String classname)
  {
    if (classname.startsWith("class "))
    {
      return classname.substring(6).trim();
    }
    return classname;
  }
}