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jfreechart example source code file (JDBCCategoryDataset.java)

This example jfreechart source code file (JDBCCategoryDataset.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - jfreechart tags/keywords

a, comparable, date, defaultcategorydataset, exception, jdbc, jdbccategorydataset, jdbccategorydataset, number, number, resultsetmetadata, sql, sqlexception, sqlexception, string, string

The jfreechart JDBCCategoryDataset.java source code

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2008, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * ------------------------
 * JDBCCategoryDataset.java
 * ------------------------
 * (C) Copyright 2002-2008, by Bryan Scott and Contributors.
 *
 * Original Author:  Bryan Scott; Andy;
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *                   Thomas Morgner;
 *
 * Changes
 * -------
 * 26-Apr-2002 : Creation based on JdbcXYDataSet, using code contributed from
 *               Andy;
 * 13-Aug-2002 : Updated Javadocs, import statements and formatting (DG);
 * 03-Sep-2002 : Added fix for bug 591385 (DG);
 * 18-Sep-2002 : Updated to support BIGINT (BS);
 * 16-Oct-2002 : Added fix for bug 586667 (DG);
 * 03-Feb-2003 : Added Types.DECIMAL (see bug report 677814) (DG);
 * 13-Jun-2003 : Added Types.TIME as suggest by Bryan Scott in the forum (DG);
 * 30-Jun-2003 : CVS Write test (BS);
 * 30-Jul-2003 : Added empty contructor and executeQuery(connection,string)
 *               method (BS);
 * 29-Aug-2003 : Added a 'transpose' flag, so that data can be easily
 *               transposed if required (DG);
 * 10-Sep-2003 : Added support for additional JDBC types (DG);
 * 24-Sep-2003 : Added clearing results from previous queries to executeQuery
 *               following being highlighted on online forum (BS);
 * 02-Dec-2003 : Throwing exceptions allows to handle errors, removed default
 *               constructor, as without a connection, a query can never be
 *               executed (TM);
 * 04-Dec-2003 : Added missing Javadocs (DG);
 * ------------- JFREECHART 1.0.0 ---------------------------------------------
 * 08-Mar-2006 : Fixed bug 1445748 where an exception is thrown if
 *               executeQuery() is called more than once (DG);
 *
 */

package org.jfree.data.jdbc;

import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Types;

import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;

/**
 * A {@link CategoryDataset} implementation over a database JDBC result set.
 * The dataset is populated via a call to {@link #executeQuery(String)} with
 * the string SQL query.  The SQL query must return at least two columns.  The
 * first column will be the category name and remaining columns values (each
 * column represents a series).  Subsequent calls to
 * {@link #executeQuery(String)} will refresh the dataset.
 * <p>
 * The database connection is read-only and no write back facility exists.
 * <p>
 * NOTE: Many people have found this class too restrictive in general use.
 * For the greatest flexibility, please consider writing your own code to read
 * data from a <code>ResultSet and populate a
 * {@link DefaultCategoryDataset} directly.
 */
public class JDBCCategoryDataset extends DefaultCategoryDataset {

    /** For serialization. */
    static final long serialVersionUID = -3080395327918844965L;

    /** The database connection. */
    private transient Connection connection;

    /**
     * A flag the controls whether or not the table is transposed.  The default
     * is 'true' because this provides the behaviour described in the
     * documentation.
     */
    private boolean transpose = true;


    /**
     * Creates a new dataset with a database connection.
     *
     * @param  url  the URL of the database connection.
     * @param  driverName  the database driver class name.
     * @param  user  the database user.
     * @param  passwd  the database user's password.
     *
     * @throws ClassNotFoundException if the driver cannot be found.
     * @throws SQLException if there is an error obtaining a connection to the
     *                      database.
     */
    public JDBCCategoryDataset(String url,
                               String driverName,
                               String user,
                               String passwd)
        throws ClassNotFoundException, SQLException {

        Class.forName(driverName);
        this.connection = DriverManager.getConnection(url, user, passwd);
    }

    /**
     * Create a new dataset with the given database connection.
     *
     * @param connection  the database connection.
     */
    public JDBCCategoryDataset(Connection connection) {
        if (connection == null) {
            throw new NullPointerException("A connection must be supplied.");
        }
        this.connection = connection;
    }

    /**
     * Creates a new dataset with the given database connection, and executes
     * the supplied query to populate the dataset.
     *
     * @param connection  the connection.
     * @param query  the query.
     *
     * @throws SQLException if there is a problem executing the query.
     */
    public JDBCCategoryDataset(Connection connection, String query)
        throws SQLException {
        this(connection);
        executeQuery(query);
    }

    /**
     * Returns a flag that controls whether or not the table values are
     * transposed when added to the dataset.
     *
     * @return A boolean.
     */
    public boolean getTranspose() {
        return this.transpose;
    }

    /**
     * Sets a flag that controls whether or not the table values are transposed
     * when added to the dataset.
     *
     * @param transpose  the flag.
     */
    public void setTranspose(boolean transpose) {
        this.transpose = transpose;
    }

    /**
     * Populates the dataset by executing the supplied query against the
     * existing database connection.  If no connection exists then no action
     * is taken.
     * <p>
     * The results from the query are extracted and cached locally, thus
     * applying an upper limit on how many rows can be retrieved successfully.
     *
     * @param query  the query.
     *
     * @throws SQLException if there is a problem executing the query.
     */
    public void executeQuery(String query) throws SQLException {
        executeQuery(this.connection, query);
    }

    /**
     * Populates the dataset by executing the supplied query against the
     * existing database connection.  If no connection exists then no action
     * is taken.
     * <p>
     * The results from the query are extracted and cached locally, thus
     * applying an upper limit on how many rows can be retrieved successfully.
     *
     * @param con  the connection.
     * @param query  the query.
     *
     * @throws SQLException if there is a problem executing the query.
     */
    public void executeQuery(Connection con, String query) throws SQLException {

        Statement statement = null;
        ResultSet resultSet = null;
        try {
            statement = con.createStatement();
            resultSet = statement.executeQuery(query);
            ResultSetMetaData metaData = resultSet.getMetaData();

            int columnCount = metaData.getColumnCount();

            if (columnCount < 2) {
                throw new SQLException(
                    "JDBCCategoryDataset.executeQuery() : insufficient columns "
                    + "returned from the database.");
            }

            // Remove any previous old data
            int i = getRowCount();
            while (--i >= 0) {
                removeRow(i);
            }

            while (resultSet.next()) {
                // first column contains the row key...
                Comparable rowKey = resultSet.getString(1);
                for (int column = 2; column <= columnCount; column++) {

                    Comparable columnKey = metaData.getColumnName(column);
                    int columnType = metaData.getColumnType(column);

                    switch (columnType) {
                        case Types.TINYINT:
                        case Types.SMALLINT:
                        case Types.INTEGER:
                        case Types.BIGINT:
                        case Types.FLOAT:
                        case Types.DOUBLE:
                        case Types.DECIMAL:
                        case Types.NUMERIC:
                        case Types.REAL: {
                            Number value = (Number) resultSet.getObject(column);
                            if (this.transpose) {
                                setValue(value, columnKey, rowKey);
                            }
                            else {
                                setValue(value, rowKey, columnKey);
                            }
                            break;
                        }
                        case Types.DATE:
                        case Types.TIME:
                        case Types.TIMESTAMP: {
                            Date date = (Date) resultSet.getObject(column);
                            Number value = new Long(date.getTime());
                            if (this.transpose) {
                                setValue(value, columnKey, rowKey);
                            }
                            else {
                                setValue(value, rowKey, columnKey);
                            }
                            break;
                        }
                        case Types.CHAR:
                        case Types.VARCHAR:
                        case Types.LONGVARCHAR: {
                            String string
                                = (String) resultSet.getObject(column);
                            try {
                                Number value = Double.valueOf(string);
                                if (this.transpose) {
                                    setValue(value, columnKey, rowKey);
                                }
                                else {
                                    setValue(value, rowKey, columnKey);
                                }
                            }
                            catch (NumberFormatException e) {
                                // suppress (value defaults to null)
                            }
                            break;
                        }
                        default:
                            // not a value, can't use it (defaults to null)
                            break;
                    }
                }
            }

            fireDatasetChanged();
        }
        finally {
            if (resultSet != null) {
                try {
                    resultSet.close();
                }
                catch (Exception e) {
                    // report this?
                }
            }
            if (statement != null) {
                try {
                    statement.close();
                }
                catch (Exception e) {
                    // report this?
                }
            }
        }
    }

}

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