Java tutorial
/* * Copyright 2008 - 2009 Eric Fenderbosch * * 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 net.fender.sql; import java.io.PrintWriter; import java.sql.Connection; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.Map; import java.util.Properties; import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; import javax.sql.DataSource; import org.apache.commons.lang.StringUtils; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * @author Eric Fenderbosch */ public abstract class ManagedConnectionDataSource implements DataSource { private static final Log log = LogFactory.getLog(ManagedConnectionDataSource.class); protected boolean validateConnectionOnAquire = false; protected String validationQuery; private String jndiName; private Properties jndiProperties; /** * default is false * * @param validateConnectionOnAquire */ public void setValidateConnectionOnAquire(boolean validateConnectionOnAquire) { this.validateConnectionOnAquire = validateConnectionOnAquire; } /** * If no validationQuery is set, then the validation check returns * !isClosed(). This query should be fast and cheap and return at least one * (ideally only one) row, something like "select 1 from dual" for Oracle or * MySQL. If this DataSource delegates to other * non-ManagedConnectionDataSources (like from a JEE container), they should * have validation turned off to avoid multiple execution of validation * queries. * * @param validationQuery */ public void setValidationQuery(String validationQuery) { this.validationQuery = validationQuery; } /** * If jndiName is set, this DataSource will attempt to bind itself in a JNDI * Context. Tested w/ Resin 3.1. * * @param jndiName */ public void setJndiName(String jndiName) { this.jndiName = jndiName; } /** * This is exposed as a Map as well as Properties because Spring doesn't * allow "ref" in a prop which some users may find restrictive. * * @param jndiProperties */ public void setJndiProperties(Map<String, String> jndiProperties) { this.jndiProperties = new Properties(); for (Map.Entry<String, String> entry : jndiProperties.entrySet()) { this.jndiProperties.setProperty(entry.getKey(), entry.getValue()); } } /** * @param jndiProperties */ public void setJndiProperties(Properties jndiProperties) { this.jndiProperties = jndiProperties; } /** * Sub-classes that implement init() should make sure to call super.init() * to ensure JNDI publication. * * @throws Exception */ public void init() throws Exception { if (jndiName != null) { Context context = null; try { if (jndiProperties == null) { context = new InitialContext(); } else { context = new InitialContext(jndiProperties); } context.rebind(jndiName, this); } finally { if (context != null) { try { context.close(); } catch (NamingException ignore) { // ignore } } } } } public final Connection getConnection() throws SQLException { ManagedConnection managedConnection = getManagedConnection(); if (validateConnectionOnAquire) { validateConnection(managedConnection); } return managedConnection; } /** * throws UnsupportedOperationException */ public final Connection getConnection(String username, String password) throws SQLException { // return getManagedConnection(username, password); throw new UnsupportedOperationException(); } /** * @return * @throws SQLException */ protected abstract ManagedConnection getManagedConnection() throws SQLException; /** * @param managedConnection * @throws SQLException */ protected abstract void close(ManagedConnection managedConnection) throws SQLException; /** * Tests if managedConnection != null, wrappedConnection != null && * !isClosed(), then runs validation query. Closes the connection on * SQLException. * * @param managedConnection * @throws InvalidConnectionException */ protected void validateConnection(ManagedConnection managedConnection) throws InvalidConnectionException { if (managedConnection == null) { throw new InvalidConnectionException("managedConnection is null"); } // only validate the base connection if (managedConnection.isValid()) { return; } managedConnection.setValid(false); Connection connection = managedConnection.getConnection(); if (connection == null) { throw new InvalidConnectionException("wrapped connection is null"); } Statement statement = null; ResultSet resultSet = null; try { if (connection.isClosed()) { throw new InvalidConnectionException("wrapped connection is closed"); } // if no validation query, then assume it is ok if (StringUtils.isBlank(validationQuery)) { managedConnection.setValid(true); return; } statement = connection.createStatement(); resultSet = statement.executeQuery(validationQuery); if (resultSet.next()) { log.debug("connection validation returned " + resultSet.getObject(1)); managedConnection.setValid(true); } } catch (SQLException e) { JdbcUtils.close(connection); throw new InvalidConnectionException(e); } finally { JdbcUtils.close(resultSet, statement); } } /** * throws UnsupportedOperationException */ public PrintWriter getLogWriter() throws SQLException { throw new UnsupportedOperationException(); } /** * throws UnsupportedOperationException */ public int getLoginTimeout() throws SQLException { throw new UnsupportedOperationException(); } /** * throws UnsupportedOperationException */ public void setLogWriter(PrintWriter out) throws SQLException { throw new UnsupportedOperationException(); } /** * throws UnsupportedOperationException */ public void setLoginTimeout(int seconds) throws SQLException { throw new UnsupportedOperationException(); } public boolean isWrapperFor(Class<?> iface) throws SQLException { return false; // throw new UnsupportedOperationException(); } /** * throws UnsupportedOperationException */ public <T> T unwrap(Class<T> iface) throws SQLException { // return null; throw new UnsupportedOperationException(); } }