Java tutorial
/** * Copyright (c) 2016, WSO2 Inc. (http://www.wso2.org) All Rights Reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.wso2.intcloud.core; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.wso2.carbon.context.PrivilegedCarbonContext; import org.wso2.carbon.utils.multitenancy.MultitenantConstants; import org.wso2.intcloud.common.IntCloudException; import org.wso2.intcloud.common.util.IntCloudUtil; import javax.naming.InitialContext; import javax.naming.NamingException; import javax.sql.DataSource; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class DBUtil { private static Log log = LogFactory.getLog(DBUtil.class); private static DataSource dataSource; private static final String DATASOURCE_NAME = "DataSourceName"; public static void initDatasource() { try { PrivilegedCarbonContext.startTenantFlow(); PrivilegedCarbonContext threadLocalCarbonContext = PrivilegedCarbonContext .getThreadLocalCarbonContext(); threadLocalCarbonContext.setTenantId(MultitenantConstants.SUPER_TENANT_ID, true); try { String datasourceName = IntCloudUtil.getPropertyValue(DATASOURCE_NAME); InitialContext context = new InitialContext(); dataSource = (DataSource) context.lookup(datasourceName); if (log.isDebugEnabled()) { log.debug("Initialized datasource : " + datasourceName + " successfully"); } } catch (NamingException e) { log.error("Error while initializing datasource : " + DATASOURCE_NAME, e); throw new ExceptionInInitializerError(e); } } finally { PrivilegedCarbonContext.endTenantFlow(); } } public static Connection getDBConnection() throws IntCloudException { Connection connection; try { connection = getDataSource().getConnection(); connection.setAutoCommit(false); } catch (SQLException e) { String msg = "Error while getting database connection"; throw new IntCloudException(msg, e); } return connection; } private static DataSource getDataSource() { if (dataSource == null) { initDatasource(); } return dataSource; } public static void closeConnection(Connection dbConnection) { if (dbConnection != null) { try { dbConnection.close(); } catch (SQLException e) { String msg = "Error while closing the database connection"; log.error(msg, e); } } } public static void closePreparedStatement(PreparedStatement preparedStatement) { if (preparedStatement != null) { try { preparedStatement.close(); } catch (SQLException e) { String msg = "Error while closing prepared statement"; log.error(msg, e); } } } /** * This method is used to close the database result set. * The intended use of this method is within a finally block. * This method will log any exceptions that is occurred while closing the database result set. * * @param resultSet The database result set that needs to be closed. */ public static void closeResultSet(ResultSet resultSet) { try { if (resultSet != null) { resultSet.close(); } } catch (SQLException e) { // This method is called within a finally block. Hence we do not throw an error from here String msg = "Could not close resultSet"; log.error(msg, e); } } public static void rollbackTransaction(Connection dbConnection) { if (dbConnection != null) { try { dbConnection.rollback(); } catch (SQLException e1) { log.error("Error while rolling back the failed transaction", e1); } } } }