001 /* 002 // $Id: OlapWrapper.java 482 2012-01-05 23:27:27Z jhyde $ 003 // 004 // Licensed to Julian Hyde under one or more contributor license 005 // agreements. See the NOTICE file distributed with this work for 006 // additional information regarding copyright ownership. 007 // 008 // Julian Hyde licenses this file to you under the Apache License, 009 // Version 2.0 (the "License"); you may not use this file except in 010 // compliance with the License. You may obtain a copy of the License at: 011 // 012 // http://www.apache.org/licenses/LICENSE-2.0 013 // 014 // Unless required by applicable law or agreed to in writing, software 015 // distributed under the License is distributed on an "AS IS" BASIS, 016 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 017 // See the License for the specific language governing permissions and 018 // limitations under the License. 019 */ 020 package org.olap4j; 021 022 import java.sql.SQLException; 023 024 /** 025 * Interface for olap4j classes which provide the ability to retrieve the 026 * delegate instance when the instance in question is in fact a proxy class. 027 * 028 * <p><code>OlapWrapper</code> duplicates the functionality of the 029 * <code>java.sql.Wrapper</code> interface (introduced in JDBC 4.0), making 030 * this functionality available to olap4j clients running in a JDBC 3.0 031 * environment. For code which will run only on JDBC 4.0 and later, Wrapper can 032 * be used, and OlapWrapper can be ignored.</p> 033 * 034 * <p>In JDBC 3.0 (JDK 1.5) and earlier, the <code>OlapWrapper</code> interface 035 * is used to convert a JDBC class to the corresponding olap4j class. For 036 * instance, write 037 * 038 * <blockquote> 039 * <pre> 040 * import java.sql.Connection; 041 * import java.sql.DriverManager; 042 * import org.olap4j.OlapConnection; 043 * import org.olap4j.OlapWrapper; 044 * 045 * Connection connection = DriverManager.getConnection("jdbc: ..."); 046 * OlapWrapper wrapper = (OlapWrapper) connection; 047 * OlapConnection olapConnection = wrapper.unwrap(OlapConnection.class); 048 * </pre> 049 * </blockquote> 050 * 051 * to create a JDBC 3.0 connection and convert it to an olap4j connection. 052 * 053 * <p>In JDBC 4.0 (JDK 1.6) and later, you don't need to use this class. All of 054 * the key JDBC classes implement <code>java.sql.Wrapper</code> interface, so 055 * you can use its <code>isWrapper</code> and <code>unwrap</code> methods 056 * without casting. For instance, write 057 * 058 * <blockquote> 059 * <pre> 060 * import java.sql.Connection; 061 * import java.sql.DriverManager; 062 * import org.olap4j.OlapConnection; 063 * 064 * Connection connection = DriverManager.getConnection("jdbc: ..."); 065 * OlapConnection olapConnection = connection.unwrap(OlapConnection.class); 066 * </pre> 067 * </blockquote> 068 * 069 * to create a JDBC 4.0 connection and convert it to an olap4j connection. 070 * 071 * @author jhyde 072 * @version $Id: OlapWrapper.java 482 2012-01-05 23:27:27Z jhyde $ 073 * @since Jun 14, 2007 074 */ 075 public interface OlapWrapper { 076 // duplicate method from java.sql.Wrapper (JDBC 4.0), so method is available 077 // in JDBC 3.0 078 <T> T unwrap(Class<T> iface) throws SQLException; 079 080 // duplicate method from java.sql.Wrapper (JDBC 4.0), so method is available 081 // in JDBC 3.0 082 boolean isWrapperFor(Class<?> iface) throws SQLException; 083 } 084 085 // End OlapWrapper.java