idgeneratorfactory.java

torque服务器源代码

package org.apache.torque.oid;

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import org.apache.torque.adapter.DB;
import org.apache.torque.adapter.IDMethod;

/**
 * A factory which instantiates {@link
 * org.apache.torque.oid.IdGenerator} implementations.
 *
 * @author <a href="mailto:[e-mail]">Daniel Rall</a>
 * @version $Id: IDGeneratorFactory.java,v 1.2 2002/11/26 23:46:56 mpoeschl Exp $
 */
public class IDGeneratorFactory
{
    /**
     * The list of ID generation method types which have associated
     * {@link org.apache.torque.oid.IdGenerator} implementations.
     */
    public static final String[] ID_GENERATOR_METHODS =
    {
        IDMethod.NATIVE, IDMethod.AUTO_INCREMENT, IDMethod.SEQUENCE
    };

    /**
     * Factory method which instantiates {@link
     * org.apache.torque.oid.IdGenerator} implementations based on the
     * return value of the provided adapter's {@link
     * org.apache.torque.adapter.DB#getIDMethodType()} method.
     * Returns <code>null</code> for unknown types.
     *
     * @param dbAdapter The type of adapter to create an ID generator for.
     * @return The appropriate ID generator (possibly <code>null</code>).
     */
    public static IdGenerator create(DB dbAdapter)
    {
        String idMethod = dbAdapter.getIDMethodType();
        if (IDMethod.AUTO_INCREMENT.equals(idMethod))
        {
            return new AutoIncrementIdGenerator(dbAdapter);
        }
        else if (IDMethod.SEQUENCE.equals(idMethod))
        {
            return new SequenceIdGenerator(dbAdapter);
        }
        else
        {
            return null;
        }
    }
}