java/jdbc-dk-driver/src/info/globalcode/sql/dk/jdbc/Driver.java
branchv_0
changeset 192 a32bfcbdee51
parent 177 5cc7fdad1452
child 195 aed11d9107bf
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/java/jdbc-dk-driver/src/info/globalcode/sql/dk/jdbc/Driver.java	Sun May 17 00:27:56 2015 +0200
@@ -0,0 +1,156 @@
+/**
+ * SQL-DK
+ * Copyright © 2015 František Kučera (frantovo.cz)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+package info.globalcode.sql.dk.jdbc;
+
+import info.globalcode.sql.dk.Constants;
+import info.globalcode.sql.dk.configuration.Configuration;
+import info.globalcode.sql.dk.configuration.ConfigurationException;
+import info.globalcode.sql.dk.configuration.DatabaseDefinition;
+import info.globalcode.sql.dk.configuration.Loader;
+import info.globalcode.sql.dk.configuration.Properties;
+import info.globalcode.sql.dk.configuration.Property;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.DriverPropertyInfo;
+import java.sql.SQLException;
+import java.sql.SQLFeatureNotSupportedException;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * <p>
+ * Meta JDBC driver that works as redirector/router. It loads SQL-DK's configuration file and
+ * instantiates a real JDBC connection (PostgreSQL, MariDB etc.) of given name.
+ * </p>
+ *
+ * <p>
+ * Raison d'être: user can define his/her database connections just once (in SQL-DK's configuration)
+ * and use them in many other programs – there is no need to define the connection (hostname,
+ * username, password, properties…) in each application again and again. User will simply connect to
+ * e.g. <code>jdbc:sql-dk://my-connection</code> and this driver reads parameters of
+ * <code>my-connection</code> from SQL-DK's configuration and returns real driver implementation.
+ * </p>
+ *
+ * <p>
+ * Of course, the real JDBC driver for given database is still needed on the class path.
+ * </p>
+ *
+ * <p>
+ * TODO: current version is quite heavy-weight, because it includes whole SQL-DK source tree. Some
+ * refactoring and separation is desired to provide more light-weight JDBC driver. Although the
+ * public interface and behavior of this driver should remain same.
+ * </p>
+ *
+ * @author Ing. František Kučera (frantovo.cz)
+ */
+public class Driver implements java.sql.Driver {
+
+	private static final Logger log = Logger.getLogger(Driver.class.getName());
+
+	private final Loader loader = new Loader();
+
+	static {
+		try {
+			DriverManager.registerDriver(new Driver());
+		} catch (SQLException e) {
+			log.log(Level.SEVERE, "Unable to register JDBC driver", e);
+		}
+	}
+
+	@Override
+	public Connection connect(String url, java.util.Properties info) throws SQLException {
+		if (acceptsURL(url)) {
+			log.log(Level.FINER, "Loading SQL-DK configuration for URL: {0}", url);
+			String name = extractDatabaseName(url);
+			log.log(Level.FINE, "Loading SQL-DK configuration for name: {0}", name);
+
+			try {
+				return getConnection(name, info);
+			} catch (ConfigurationException e) {
+				log.log(Level.SEVERE, "Unable to load SQL-DK configuration for name: {0}. Is it defined in {1}?", new Object[]{name, Constants.CONFIG_FILE});
+				throw new SQLException("Unable to load SQL-DK configuration for name: " + name, e);
+			}
+		} else {
+			throw new SQLException("Unsupported URL: " + url);
+		}
+	}
+
+	private Connection getConnection(String connectionName, java.util.Properties info) throws SQLException, ConfigurationException {
+		Configuration c = loader.loadConfiguration();
+		DatabaseDefinition dd = c.getDatabase(connectionName);
+
+		if (acceptsURL(dd.getUrl())) {
+			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});
+			throw new ConfigurationException("SQL-DK meta JDBC driver loops to itself.");
+		} else {
+			return Loader.jdbcConnect(dd, translate(info));
+		}
+	}
+
+	private String extractDatabaseName(String url) {
+		return url.split("//", 2)[1];
+	}
+
+	/**
+	 * TODO: refactor/move, reuse
+	 *
+	 * @param info
+	 * @return
+	 */
+	private Properties translate(java.util.Properties info) {
+		Properties properties = new Properties();
+
+		for (String name : info.stringPropertyNames()) {
+			String value = info.getProperty(name);
+			properties.add(new Property(name, value));
+		}
+
+		return properties;
+	}
+
+	@Override
+	public boolean acceptsURL(String url) throws SQLException {
+		return url != null && url.startsWith("jdbc:sql-dk://");
+	}
+
+	@Override
+	public DriverPropertyInfo[] getPropertyInfo(String url, java.util.Properties info) throws SQLException {
+		return new DriverPropertyInfo[0];
+	}
+
+	@Override
+	public int getMajorVersion() {
+		return 0;
+	}
+
+	@Override
+	public int getMinorVersion() {
+		return 1;
+	}
+
+	@Override
+	public boolean jdbcCompliant() {
+		return false;
+	}
+
+	@Override
+	public Logger getParentLogger() throws SQLFeatureNotSupportedException {
+		throw new SQLFeatureNotSupportedException("Not supported yet.");
+	}
+
+}