1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package java.sql; 19 20 /** 21 * This class is an actual usage of the wrapper pattern for JDBC classes. 22 * Developers can get the delegate instance when the instance may be a proxy 23 * class. 24 * 25 * @since 1.6 26 */ 27 public interface Wrapper { 28 29 /** 30 * Returns an object that implements the given interface. If the caller is 31 * not a wrapper, a SQLException will be thrown. 32 * 33 * @param iface - 34 * the class that defines the interface 35 * @return - an object that implements the interface 36 * @throws SQLException - 37 * if there is no object implementing the specific interface 38 */ unwrap(Class<T> iface)39 <T> T unwrap(Class<T> iface) throws SQLException; 40 41 /** 42 * If the caller is a wrapper of the class or implements the given 43 * interface, the methods return false and vice versa. 44 * 45 * @param iface - 46 * the class that defines the interface 47 * @return - true if the instance implements the interface 48 * @throws SQLException - 49 * when an error occurs when judges the object 50 */ isWrapperFor(Class<?> iface)51 boolean isWrapperFor(Class<?> iface) throws SQLException; 52 } 53