java/jdbc-dk-driver/src/info/globalcode/sql/dk/jdbc/Driver.java
author František Kučera <franta-hg@frantovo.cz>
Sun, 24 May 2015 19:10:25 +0200
branchv_0
changeset 200 2e351d7c26c4
parent 195 aed11d9107bf
child 235 8ce612cca4d8
permissions -rw-r--r--
InfoLister: new listings: --list-java-properties and --list-environment-variables
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/**
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 * SQL-DK
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 * Copyright © 2015 František Kučera (frantovo.cz)
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 *
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 * This program is free software: you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation, either version 3 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program. If not, see <http://www.gnu.org/licenses/>.
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 */
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package info.globalcode.sql.dk.jdbc;
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import info.globalcode.sql.dk.Constants;
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import info.globalcode.sql.dk.configuration.Configuration;
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import info.globalcode.sql.dk.configuration.ConfigurationException;
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import info.globalcode.sql.dk.configuration.DatabaseDefinition;
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import info.globalcode.sql.dk.configuration.Loader;
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import info.globalcode.sql.dk.configuration.Properties;
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import info.globalcode.sql.dk.configuration.Property;
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import java.sql.Connection;
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import java.sql.DriverManager;
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import java.sql.DriverPropertyInfo;
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import java.sql.SQLException;
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import java.sql.SQLFeatureNotSupportedException;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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/**
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 * <p>
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 * Meta JDBC driver that works as redirector/router. It loads SQL-DK's configuration file and
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 * instantiates a real JDBC connection (PostgreSQL, MariDB etc.) of given name.
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 * </p>
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 *
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 * <p>
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 * Raison d'être: user can define his/her database connections just once (in SQL-DK's configuration)
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 * and use them in many other programs – there is no need to define the connection (hostname,
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 * username, password, properties…) in each application again and again. User will simply connect to
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 * e.g. <code>jdbc:sql-dk://my-connection</code> and this driver reads parameters of
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 * <code>my-connection</code> from SQL-DK's configuration and returns real driver implementation.
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 * </p>
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 *
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 * <p>
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 * Of course, the real JDBC driver for given database is still needed on the class path.
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 * </p>
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 *
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 * <p>
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 * TODO: current version is quite heavy-weight, because it includes whole SQL-DK source tree. Some
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 * refactoring and separation is desired to provide more light-weight JDBC driver. However the
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 * public interface and behavior of this driver should remain unchanged.
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 * </p>
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 *
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 * @author Ing. František Kučera (frantovo.cz)
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 */
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public class Driver implements java.sql.Driver {
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	private static final Logger log = Logger.getLogger(Driver.class.getName());
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	private final Loader loader = new Loader();
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	static {
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		try {
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			DriverManager.registerDriver(new Driver());
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		} catch (SQLException e) {
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			log.log(Level.SEVERE, "Unable to register JDBC driver", e);
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		}
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	}
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	@Override
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	public Connection connect(String url, java.util.Properties info) throws SQLException {
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		if (acceptsURL(url)) {
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			log.log(Level.FINER, "Loading SQL-DK configuration for URL: {0}", url);
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			String name = extractDatabaseName(url);
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			log.log(Level.FINE, "Loading SQL-DK configuration for name: {0}", name);
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			try {
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				return getConnection(name, info);
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			} catch (ConfigurationException e) {
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				log.log(Level.SEVERE, "Unable to load SQL-DK configuration for name: {0}. Is it defined in {1}?", new Object[]{name, Constants.CONFIG_FILE});
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				throw new SQLException("Unable to load SQL-DK configuration for name: " + name, e);
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			}
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		} else {
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			throw new SQLException("Unsupported URL: " + url);
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		}
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	}
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	private Connection getConnection(String connectionName, java.util.Properties info) throws SQLException, ConfigurationException {
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		Configuration c = loader.loadConfiguration();
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		DatabaseDefinition dd = c.getDatabase(connectionName);
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		if (acceptsURL(dd.getUrl())) {
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			log.log(Level.SEVERE, "SQL-DK meta JDBC driver loops to itself: {0} → {1} Please check {2}", new Object[]{connectionName, dd.getUrl(), Constants.CONFIG_FILE});
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			throw new ConfigurationException("SQL-DK meta JDBC driver loops to itself.");
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		} else {
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			return Loader.jdbcConnect(dd, translate(info));
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		}
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	}
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	private String extractDatabaseName(String url) {
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		return url.split("//", 2)[1];
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	}
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	/**
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	 * TODO: refactor/move, reuse
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	 *
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	 * @param info
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	 * @return
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	 */
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	private Properties translate(java.util.Properties info) {
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		Properties properties = new Properties();
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		for (String name : info.stringPropertyNames()) {
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			String value = info.getProperty(name);
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			properties.add(new Property(name, value));
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		}
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		return properties;
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	}
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	@Override
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	public boolean acceptsURL(String url) throws SQLException {
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		return url != null && url.startsWith("jdbc:sql-dk://");
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	}
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	@Override
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	public DriverPropertyInfo[] getPropertyInfo(String url, java.util.Properties info) throws SQLException {
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		return new DriverPropertyInfo[0];
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	}
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	@Override
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	public int getMajorVersion() {
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		return 0;
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	}
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	@Override
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	public int getMinorVersion() {
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		return 1;
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	}
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	@Override
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	public boolean jdbcCompliant() {
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		return false;
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	}
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	@Override
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	public Logger getParentLogger() throws SQLFeatureNotSupportedException {
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		throw new SQLFeatureNotSupportedException("Not supported yet.");
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	}
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}