/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.   See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership. 
 * The ASF licenses this file to You 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 java.sql;

/**
 * This class is an actual usage of the wrapper pattern for JDBC classes. 
 * Developers can get the delegate instance when the instance may be a proxy
 * class. 
 *
 * @since 1.6
 */
public interface Wrapper {

    /**
     * Returns an object that implements the given interface.  If the caller is
     * not a wrapper, a SQLException will be thrown. 
     *
     * @param iface -
     *            the class that defines the interface
     * @return - an object that implements the interface
     * @throws SQLException -
     *             if there is no object implementing the specific interface
     */
    <T> T unwrap(Class<T> iface) throws SQLException;

    /**
     * If the caller is a wrapper of the class or implements the given
     * interface, the methods return false and vice versa. 
     *
     * @param iface -
     *            the class that defines the interface
     * @return - true if the instance implements the interface
     * @throws SQLException -
     *             when an error occurs when judges the object
     */
    boolean isWrapperFor(Class<? > iface) throws SQLException;
}
