Java tutorial
/* ************************************************************************ ******************* CANADIAN ASTRONOMY DATA CENTRE ******************* ************** CENTRE CANADIEN DE DONNES ASTRONOMIQUES ************** * * (c) 2009. (c) 2009. * Government of Canada Gouvernement du Canada * National Research Council Conseil national de recherches * Ottawa, Canada, K1A 0R6 Ottawa, Canada, K1A 0R6 * All rights reserved Tous droits rservs * * NRC disclaims any warranties, Le CNRC dnie toute garantie * expressed, implied, or nonce, implicite ou lgale, * statutory, of any kind with de quelque nature que ce * respect to the software, soit, concernant le logiciel, * including without limitation y compris sans restriction * any warranty of merchantability toute garantie de valeur * or fitness for a particular marchande ou de pertinence * purpose. NRC shall not be pour un usage particulier. * liable in any event for any Le CNRC ne pourra en aucun cas * damages, whether direct or tre tenu responsable de tout * indirect, special or general, dommage, direct ou indirect, * consequential or incidental, particulier ou gnral, * arising from the use of the accessoire ou fortuit, rsultant * software. Neither the name de l'utilisation du logiciel. Ni * of the National Research le nom du Conseil National de * Council of Canada nor the Recherches du Canada ni les noms * names of its contributors may de ses participants ne peuvent * be used to endorse or promote tre utiliss pour approuver ou * products derived from this promouvoir les produits drivs * software without specific prior de ce logiciel sans autorisation * written permission. pralable et particulire * par crit. * * This file is part of the Ce fichier fait partie du projet * OpenCADC project. OpenCADC. * * OpenCADC is free software: OpenCADC est un logiciel libre ; * you can redistribute it and/or vous pouvez le redistribuer ou le * modify it under the terms of modifier suivant les termes de * the GNU Affero General Public la GNU Affero General Public * License as published by the License? telle que publie * Free Software Foundation, par la Free Software Foundation * either version 3 of the : soit la version 3 de cette * License, or (at your option) licence, soit ( votre gr) * any later version. toute version ultrieure. * * OpenCADC is distributed in the OpenCADC est distribu * hope that it will be useful, dans lespoir quil vous * but WITHOUT ANY WARRANTY; sera utile, mais SANS AUCUNE * without even the implied GARANTIE : sans mme la garantie * warranty of MERCHANTABILITY implicite de COMMERCIALISABILIT * or FITNESS FOR A PARTICULAR ni dADQUATION UN OBJECTIF * PURPOSE. See the GNU Affero PARTICULIER. Consultez la Licence * General Public License for Gnrale Publique GNU Affero * more details. pour plus de dtails. * * You should have received Vous devriez avoir reu une * a copy of the GNU Affero copie de la Licence Gnrale * General Public License along Publique GNU Affero avec * with OpenCADC. If not, see OpenCADC ; si ce nest * <http://www.gnu.org/licenses/>. pas le cas, consultez : * <http://www.gnu.org/licenses/>. * * $Revision: 4 $ * ************************************************************************ */ package ca.nrc.cadc.db; import java.sql.Connection; import java.sql.DatabaseMetaData; import java.sql.SQLException; import java.util.Properties; import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; import javax.naming.NoInitialContextException; import javax.sql.DataSource; import org.apache.log4j.Level; import org.apache.log4j.Logger; import org.springframework.dao.TransientDataAccessException; import org.springframework.jdbc.CannotGetJdbcConnectionException; import org.springframework.jdbc.datasource.SingleConnectionDataSource; import org.springframework.transaction.CannotCreateTransactionException; /** * Utility class for obtaining JDBC DataSources. * * @author pdowler */ public class DBUtil { private static final Logger log = Logger.getLogger(DBUtil.class); public static String DEFAULT_JNDI_ENV_CONTEXT = "java:/comp/env"; /** * Create a DataSource with a single connection to the server. The DataSource * is tested before return. All failures are thrown as RuntimeException * with a Throwable (cause). * * @param config * @return a connected single connection DataSource * @throws DBConfigException */ public static DataSource getDataSource(ConnectionConfig config) throws DBConfigException { return getDataSource(config, false, true); } /** * Create a DataSource with a single connection to the server. All failures * are thrown as RuntimeException with a Throwable (cause). * * @param config * @param suppressClose suppress close calls on the underlying Connection * @param test test the datasource before return (might throw) * @return a connected single connection DataSource * @throws DBConfigException */ public static DataSource getDataSource(ConnectionConfig config, boolean suppressClose, boolean test) throws DBConfigException { try { log.debug("server: " + config.getServer()); log.debug("driver: " + config.getDriver()); log.debug("url: " + config.getURL()); log.debug("database: " + config.getDatabase()); // load JDBC driver Class.forName(config.getDriver()); SingleConnectionDataSource ds = new SingleConnectionDataSource(config.getURL(), config.getUsername(), config.getPassword(), suppressClose); Properties props = new Properties(); props.setProperty("APPLICATIONNAME", getMainClass()); ds.setConnectionProperties(props); if (test) testDS(ds, true); return ds; } catch (ClassNotFoundException ex) { throw new DBConfigException("failed to load JDBC driver: " + config.getDriver(), ex); } catch (SQLException ex) { throw new DBConfigException("failed to open connection: " + config.getURL(), ex); } } /** * Create a data source with the specified configuration and bind it in a * standalone JNDI context so that a later call to getJNDIDataSource(String) * will return it. This is for use in command-line apps (not application * servers!!!!) and test code. This method uses the default JDNI environment * context that works in Tomcat App server as the name s * * @param dataSourceName * @param config * @throws NamingException */ public static void createJNDIDataSource(String dataSourceName, ConnectionConfig config) throws NamingException { createJNDIDataSource(dataSourceName, DEFAULT_JNDI_ENV_CONTEXT, config); } /** * Create a JNDI DataSOurce resource with the specified name and environment context. * * @param dataSourceName * @param envContextName * @param config * @throws NamingException */ public static void createJNDIDataSource(String dataSourceName, String envContextName, ConnectionConfig config) throws NamingException { log.debug("createDataSource: " + dataSourceName + " START"); StandaloneContextFactory.initJNDI(); Context initContext = new InitialContext(); Context envContext = (Context) initContext.lookup(envContextName); if (envContext == null) { envContext = initContext.createSubcontext(envContextName); } log.debug("env: " + envContext); DataSource ds = getDataSource(config); envContext.bind(dataSourceName, ds); log.debug("createDataSource: " + dataSourceName + " DONE"); } /** * This just calls findJNDIDataSource(String). * * @param dataSource * @return * @throws NamingException * @deprecated */ public static DataSource getDataSource(String dataSource) throws NamingException { return findJNDIDataSource(dataSource); } /** * Find a JNDI DataSource in an application server context. This is a * convenience method for finding a DataSource via the default context * (java:/comp/env) that Tomcat uses. * * @param dataSource JNDI name of the data source * @throws NamingException if the context name cannot be resolved * @return a DataSource found via JNDI */ public static DataSource findJNDIDataSource(String dataSource) throws NamingException { return findJNDIDataSource(dataSource, DEFAULT_JNDI_ENV_CONTEXT); } /** * Find a JNDI DataSource in the specified context. * * @param dataSource * @param envContextName * @return * @throws NamingException */ public static DataSource findJNDIDataSource(String dataSource, String envContextName) throws NamingException { log.debug("getDataSource: " + dataSource); Context initContext = new InitialContext(); Context envContext = (Context) initContext.lookup(envContextName); DataSource ds = (DataSource) envContext.lookup(dataSource); return ds; } /** * Return true if this is a known Spring DAO transient exception. * @param t * @return */ public static boolean isTransientDBException(Throwable t) { if (t instanceof TransientDataAccessException || t instanceof CannotGetJdbcConnectionException || t instanceof CannotCreateTransactionException) { return true; } return false; } private static void testDS(DataSource ds, boolean keepOpen) throws SQLException { Connection con = null; try { con = ds.getConnection(); DatabaseMetaData meta = con.getMetaData(); if (!log.getEffectiveLevel().equals(Level.DEBUG)) return; log.debug("connected to server: " + meta.getDatabaseProductName() + " " + meta.getDatabaseMajorVersion() + "." + meta.getDatabaseMinorVersion() + " driver: " + meta.getDriverName() + " " + meta.getDriverMajorVersion() + "." + meta.getDriverMinorVersion()); } finally { if (!keepOpen && con != null) try { con.close(); } catch (Exception ignore) { } } } /** * Try to infer a suitable application name. * * TODO: make this config more generic and accessible to calling code * * @return */ public static String getMainClass() { String ret = "java"; try { throw new RuntimeException(); } catch (RuntimeException rex) { StackTraceElement[] st = rex.getStackTrace(); for (int i = 0; i < st.length; i++) if (st[i].getClassName().startsWith("ca.nrc.cadc.")) ret = st[i].getClassName(); } ret = shortenClassName(ret); return ret; } private static String shortenClassName(String cname) { String ret = cname; // truncate top-level packages if (ret.startsWith("ca.nrc.cadc.")) ret = ret.substring("ca.nrc.cadc.".length()); while (ret.length() > 30) // sybase program_name limit { // strip off one package name at a time int ii = ret.indexOf('.'); if (ii > 0) ret = ret.substring(ii + 1); else ret = ret.substring(0, 30); } return ret; } }