root/trunk/org.bridgedb.rdb/src/org/bridgedb/rdb/SimpleGdbFactory.java @ 318

// BridgeDb,
// An abstraction layer for identifer mapping services, both local and online.
// Copyright 2006-2009 BridgeDb developers
//
// 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.bridgedb.rdb;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import org.bridgedb.IDMapperException;

/**
 * Factory class that instantiates the correct SimpleGdb implementation
 * for a new / existing gdb,
 * based on the schema version.
 * Use this class for creating / connecting to any SimpleGdb database.
 */
public final class SimpleGdbFactory 
{
        /** private constructor prevents instantiation. */
        private SimpleGdbFactory() {};
        
        /**
         * Opens a connection to the Gene Database located in the given file.
         * <p>
         * Use this instead of constructor to create an instance of SimpleGdb that matches the schema version.
         * @param connectionString a JDBC Connection string 
         * @return a new Gdb
         * @throws IDMapperException on failure
        */
        public static SimpleGdb createInstance(String dbName, String connectionString) throws IDMapperException
        {
                if(connectionString == null) throw new NullPointerException();  

                int version = 0;
                Connection con = null;
                ResultSet r = null;
                Statement stmt = null;
                try 
                {
                        con = DriverManager.getConnection(connectionString);
                        stmt = con.createStatement();
                        r = stmt.executeQuery("SELECT schemaversion FROM info");
                        if(r.next()) version = r.getInt(1);
                } 
                catch (SQLException e) 
                {
                        //Ignore, older db's don't even have schema version
                }
                finally
                {
                        if (r != null) try { r.close(); } catch (SQLException ignore) {}
                        if (stmt != null) try { stmt.close(); } catch (SQLException ignore) {}
                        if (con != null) try { con.close(); } catch (SQLException ignore) {}
                }
                
                switch (version)
                {
                case 2:
                        return new SimpleGdbImpl2(dbName, connectionString);
                case 3:
                        return new SimpleGdbImpl3(dbName, connectionString);
                //NB add future schema versions here
                default:
                        throw new IDMapperException ("Unrecognized schema version '" + version + "', please make sure you have the latest " +
                                        "version of this software and databases");
                }               
        }
}