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| 1 | /* | ||
| 2 | * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package java.sql; | ||
| 27 | |||
| 28 | /** | ||
| 29 | * Interface for JDBC classes which provide the ability to retrieve the delegate instance when the instance | ||
| 30 | * in question is in fact a proxy class. | ||
| 31 | * <p> | ||
| 32 | * The wrapper pattern is employed by many JDBC driver implementations to provide extensions beyond | ||
| 33 | * the traditional JDBC API that are specific to a data source. Developers may wish to gain access to | ||
| 34 | * these resources that are wrapped (the delegates) as proxy class instances representing the | ||
| 35 | * the actual resources. This interface describes a standard mechanism to access | ||
| 36 | * these wrapped resources | ||
| 37 | * represented by their proxy, to permit direct access to the resource delegates. | ||
| 38 | * | ||
| 39 | * @since 1.6 | ||
| 40 | */ | ||
| 41 | |||
| 42 | public interface Wrapper { | ||
| 43 | |||
| 44 | /** | ||
| 45 | * Returns an object that implements the given interface to allow access to | ||
| 46 | * non-standard methods, or standard methods not exposed by the proxy. | ||
| 47 | * | ||
| 48 | * If the receiver implements the interface then the result is the receiver | ||
| 49 | * or a proxy for the receiver. If the receiver is a wrapper | ||
| 50 | * and the wrapped object implements the interface then the result is the | ||
| 51 | * wrapped object or a proxy for the wrapped object. Otherwise return the | ||
| 52 | * the result of calling <code>unwrap</code> recursively on the wrapped object | ||
| 53 | * or a proxy for that result. If the receiver is not a | ||
| 54 | * wrapper and does not implement the interface, then an <code>SQLException</code> is thrown. | ||
| 55 | * | ||
| 56 | * @param iface A Class defining an interface that the result must implement. | ||
| 57 | * @return an object that implements the interface. May be a proxy for the actual implementing object. | ||
| 58 | * @throws java.sql.SQLException If no object found that implements the interface | ||
| 59 | * @since 1.6 | ||
| 60 | */ | ||
| 61 | <T> T unwrap(java.lang.Class<T> iface) throws java.sql.SQLException; | ||
| 62 | |||
| 63 | /** | ||
| 64 | * Returns true if this either implements the interface argument or is directly or indirectly a wrapper | ||
| 65 | * for an object that does. Returns false otherwise. If this implements the interface then return true, | ||
| 66 | * else if this is a wrapper then return the result of recursively calling <code>isWrapperFor</code> on the wrapped | ||
| 67 | * object. If this does not implement the interface and is not a wrapper, return false. | ||
| 68 | * This method should be implemented as a low-cost operation compared to <code>unwrap</code> so that | ||
| 69 | * callers can use this method to avoid expensive <code>unwrap</code> calls that may fail. If this method | ||
| 70 | * returns true then calling <code>unwrap</code> with the same argument should succeed. | ||
| 71 | * | ||
| 72 | * @param iface a Class defining an interface. | ||
| 73 | * @return true if this implements the interface or directly or indirectly wraps an object that does. | ||
| 74 | * @throws java.sql.SQLException if an error occurs while determining whether this is a wrapper | ||
| 75 | * for an object with the given interface. | ||
| 76 | * @since 1.6 | ||
| 77 | */ | ||
| 78 | boolean isWrapperFor(java.lang.Class<?> iface) throws java.sql.SQLException; | ||
| 79 | |||
| 80 | } | ||