/*
* Copyright 2010 the original author or authors.
*
* 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.springframework.jdbc.versioned;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Set;
import java.util.TreeSet;
import javax.sql.DataSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* DatabaseUpgrader implementation that expects to be fully configured programatically.
* Stores version information in a DatabaseVersion table in the database.
* @author Keith Donald
*/
public class GenericDatabaseUpgrader implements DatabaseUpgrader {
private static final Logger logger = LoggerFactory.getLogger(GenericDatabaseUpgrader.class);
private final DataSource dataSource;
private final Set<DatabaseChangeSet> changeSets = new TreeSet<DatabaseChangeSet>();
private DatabaseVersion currentVersion;
/**
* Constructs a database upgrader that upgrades the Database accessed by the provided {@link DataSource}.
* @param dataSource the factory for database connections
*/
public GenericDatabaseUpgrader(DataSource dataSource) {
this.dataSource = dataSource;
currentVersion = findCurrentVersion();
if (logger.isInfoEnabled()) {
logger.info("Database is at Version " + currentVersion);
}
}
/**
* Add a change set to the list of change sets to run through when upgrading the Database.
*/
public void addChangeSet(DatabaseChangeSet changeSet) {
changeSets.add(changeSet);
}
// implementing DatabaseUpgrader
public DatabaseVersion getCurrentDatabaseVersion() {
return currentVersion;
}
public void run() {
for (DatabaseChangeSet changeSet : changeSets) {
if (currentVersion.lessThan(changeSet.getVersion())) {
if (logger.isInfoEnabled()) {
logger.info("Upgrading Database to Version " + changeSet.getVersion());
}
currentVersion = changeSet.apply(dataSource);
if (logger.isInfoEnabled()) {
logger.info("Database is at Version " + currentVersion);
}
}
}
}
// internal helpers
private DatabaseVersion findCurrentVersion() {
Connection connection = null;
try {
connection = dataSource.getConnection();
DatabaseMetaData metadata = connection.getMetaData();
ResultSet result = metadata.getTables(null, null, "DATABASEVERSION", null);
try {
// checks if the table exists, if not, creates it
if (result.next()) {
Statement stmt = connection.createStatement();
try {
stmt.execute("select value from DatabaseVersion");
ResultSet queryResult = stmt.getResultSet();
try {
queryResult.next();
String value = queryResult.getString("value");
queryResult.close();
return DatabaseVersion.valueOf(value);
} finally {
queryResult.close();
}
} finally {
stmt.close();
}
} else {
Statement stmt = connection.createStatement();
try {
stmt.execute("create table DatabaseVersion (value varchar not null)");
stmt.execute("insert into DatabaseVersion (value) values ('0')");
} finally {
stmt.close();
}
return DatabaseVersion.zero();
}
} finally {
result.close();
}
} catch (SQLException e) {
throw new RuntimeException("Unable to determine database version", e);
} finally {
if (connection != null) {
try {
connection.close();
} catch (SQLException e) {
}
}
}
}
}