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  package org.apache.cayenne.dba.mysql;
  
  import org.apache.cayenne.configuration.runtime.DbAdapterDetector;
  import org.apache.cayenne.dba.DbAdapter;
  import org.apache.cayenne.di.AdhocObjectFactory;
  import org.apache.cayenne.di.Inject;
  
  import java.sql.DatabaseMetaData;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.sql.Statement;
  
  /**
   * Detects MySQL database from JDBC metadata.
   * 
   * @since 1.2
   */
  public class MySQLSniffer implements DbAdapterDetector {
  
  	protected AdhocObjectFactory objectFactory;
  
  	public MySQLSniffer(@Inject AdhocObjectFactory objectFactory) {
  		this.objectFactory = objectFactory;
  	}
  
  	@Override
  	public DbAdapter createAdapter(DatabaseMetaData md) throws SQLException {
  		String dbName = md.getDatabaseProductName();
  		if (dbName == null || !dbName.toUpperCase().contains("MYSQL")) {
  			return null;
  		}
  
  		// if InnoDB is used as a default engine, allow PK
  
  		String adapterStorageEngine = MySQLAdapter.DEFAULT_STORAGE_ENGINE;
  
  		try (Statement statement = md.getConnection().createStatement()) {
  			// http://dev.mysql.com/doc/refman/5.0/en/storage-engines.html
  			// per link above "table type" concept is deprecated in favor of
  			// "storage
  			// engine". Not sure if we should check "storage_engine" variable
  			// and in what
  			// version of MySQL it got introduced...
  
  			try (ResultSet rs = statement.executeQuery("SHOW VARIABLES LIKE 'table_type'")) {
  				if (rs.next()) {
  					String storageEngine = rs.getString(2);
  					if (storageEngine != null) {
  						adapterStorageEngine = storageEngine;
  					}
  				}
  			}
  		}
  
  		MySQLAdapter adapter = objectFactory.newInstance(MySQLAdapter.class, MySQLAdapter.class.getName());
  		adapter.setStorageEngine(adapterStorageEngine);
  
  		return adapter;
  	}
  }
  