jdbccategorydataset.java

来自「JfreeChart 常用图表例子」· Java 代码 · 共 307 行

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2005, 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
 * in the United States and other countries.]
 *
 * ------------------------
 * JDBCCategoryDataset.java
 * ------------------------
 * (C) Copyright 2002-2005, 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);
 *
 */

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 executeQuery 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.
 * executeQuery can be called a number of times.
 * <p>
 * The database connection is read-only and no write back facility exists.
 */
public class JDBCCategoryDataset extends DefaultCategoryDataset {

    /** 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();
            for (; i > 0; --i) {
                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?
                }
            }
        }
    }

}