Java tutorial
/* * Copyright (c) 2015, WSO2 Inc. (http://www.wso2.org) All Rights Reserved. * * WSO2 Inc. licenses this file to you 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.coffeeking.connectedcup.plugin.impl.dao; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.coffeeking.connectedcup.plugin.constants.ConnectedCupConstants; import org.coffeeking.connectedcup.plugin.exception.ConnectedCupDeviceMgtPluginException; import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; import javax.sql.DataSource; import java.sql.Connection; import java.sql.SQLException; public class ConnectedCupDAOUtil { private static final Log log = LogFactory.getLog(ConnectedCupDAOUtil.class); static DataSource dataSource; private static ThreadLocal<Connection> currentConnection = new ThreadLocal<Connection>(); public ConnectedCupDAOUtil() { initConnectedCupDAO(); } public static void initConnectedCupDAO() { try { Context ctx = new InitialContext(); dataSource = (DataSource) ctx.lookup(ConnectedCupConstants.DATA_SOURCE_NAME); } catch (NamingException e) { log.error("Error while looking up the data source: " + ConnectedCupConstants.DATA_SOURCE_NAME); } } public ConnectedCupDAO getConnectedCupDeviceDAO() { return new ConnectedCupDAO(); } public static void beginTransaction() throws ConnectedCupDeviceMgtPluginException { try { Connection conn = dataSource.getConnection(); conn.setAutoCommit(false); currentConnection.set(conn); } catch (SQLException e) { throw new ConnectedCupDeviceMgtPluginException("Error occurred while retrieving datasource connection", e); } } public static Connection getConnection() throws ConnectedCupDeviceMgtPluginException { if (currentConnection.get() == null) { try { currentConnection.set(dataSource.getConnection()); } catch (SQLException e) { throw new ConnectedCupDeviceMgtPluginException( "Error occurred while retrieving data source connection", e); } } return currentConnection.get(); } public static void commitTransaction() throws ConnectedCupDeviceMgtPluginException { try { Connection conn = currentConnection.get(); if (conn != null) { conn.commit(); } else { if (log.isDebugEnabled()) { log.debug("Datasource connection associated with the current thread is null, " + "hence commit has not been attempted"); } } } catch (SQLException e) { throw new ConnectedCupDeviceMgtPluginException("Error occurred while committing the transaction", e); } finally { closeConnection(); } } public static void closeConnection() throws ConnectedCupDeviceMgtPluginException { Connection con = currentConnection.get(); if (con != null) { try { con.close(); } catch (SQLException e) { log.error("Error occurred while close the connection"); } } currentConnection.remove(); } public static void rollbackTransaction() throws ConnectedCupDeviceMgtPluginException { try { Connection conn = currentConnection.get(); if (conn != null) { conn.rollback(); } else { if (log.isDebugEnabled()) { log.debug("Datasource connection associated with the current thread is null, " + "hence rollback has not been attempted"); } } } catch (SQLException e) { throw new ConnectedCupDeviceMgtPluginException("Error occurred while rollback the transaction", e); } finally { closeConnection(); } } }