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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 | +} | |