Java tutorial
/* * Copyright (c) 1998, 2006, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.sql; /** * The interface used for the custom mapping of an SQL user-defined type (UDT) to * a class in the Java programming language. The class object for a class * implementing the <code>SQLData</code> interface will be entered in the * appropriate <code>Connection</code> object's type map along with the SQL * name of the UDT for which it is a custom mapping. * <P> * Typically, a <code>SQLData</code> implementation * will define a field for each attribute of an SQL structured type or a * single field for an SQL <code>DISTINCT</code> type. When the UDT is * retrieved from a data source with the <code>ResultSet.getObject</code> * method, it will be mapped as an instance of this class. A programmer * can operate on this class instance just as on any other object in the * Java programming language and then store any changes made to it by * calling the <code>PreparedStatement.setObject</code> method, * which will map it back to the SQL type. * <p> * It is expected that the implementation of the class for a custom * mapping will be done by a tool. In a typical implementation, the * programmer would simply supply the name of the SQL UDT, the name of * the class to which it is being mapped, and the names of the fields to * which each of the attributes of the UDT is to be mapped. The tool will use * this information to implement the <code>SQLData.readSQL</code> and * <code>SQLData.writeSQL</code> methods. The <code>readSQL</code> method * calls the appropriate <code>SQLInput</code> methods to read * each attribute from an <code>SQLInput</code> object, and the * <code>writeSQL</code> method calls <code>SQLOutput</code> methods * to write each attribute back to the data source via an * <code>SQLOutput</code> object. * <P> * An application programmer will not normally call <code>SQLData</code> methods * directly, and the <code>SQLInput</code> and <code>SQLOutput</code> methods * are called internally by <code>SQLData</code> methods, not by application code. * * @since 1.2 */ public interface SQLData { /** * Returns the fully-qualified * name of the SQL user-defined type that this object represents. * This method is called by the JDBC driver to get the name of the * UDT instance that is being mapped to this instance of * <code>SQLData</code>. * * @return the type name that was passed to the method <code>readSQL</code> * when this object was constructed and populated * @exception SQLException if there is a database access error * @exception SQLFeatureNotSupportedException if the JDBC driver does not support * this method * @since 1.2 */ String getSQLTypeName() throws SQLException; /** * Populates this object with data read from the database. * The implementation of the method must follow this protocol: * <UL> * <LI>It must read each of the attributes or elements of the SQL * type from the given input stream. This is done * by calling a method of the input stream to read each * item, in the order that they appear in the SQL definition * of the type. * <LI>The method <code>readSQL</code> then * assigns the data to appropriate fields or * elements (of this or other objects). * Specifically, it must call the appropriate <i>reader</i> method * (<code>SQLInput.readString</code>, <code>SQLInput.readBigDecimal</code>, * and so on) method(s) to do the following: * for a distinct type, read its single data element; * for a structured type, read a value for each attribute of the SQL type. * </UL> * The JDBC driver initializes the input stream with a type map * before calling this method, which is used by the appropriate * <code>SQLInput</code> reader method on the stream. * * @param stream the <code>SQLInput</code> object from which to read the data for * the value that is being custom mapped * @param typeName the SQL type name of the value on the data stream * @exception SQLException if there is a database access error * @exception SQLFeatureNotSupportedException if the JDBC driver does not support * this method * @see SQLInput * @since 1.2 */ void readSQL(SQLInput stream, String typeName) throws SQLException; /** * Writes this object to the given SQL data stream, converting it back to * its SQL value in the data source. * The implementation of the method must follow this protocol:<BR> * It must write each of the attributes of the SQL type * to the given output stream. This is done by calling a * method of the output stream to write each item, in the order that * they appear in the SQL definition of the type. * Specifically, it must call the appropriate <code>SQLOutput</code> writer * method(s) (<code>writeInt</code>, <code>writeString</code>, and so on) * to do the following: for a Distinct Type, write its single data element; * for a Structured Type, write a value for each attribute of the SQL type. * * @param stream the <code>SQLOutput</code> object to which to write the data for * the value that was custom mapped * @exception SQLException if there is a database access error * @exception SQLFeatureNotSupportedException if the JDBC driver does not support * this method * @see SQLOutput * @since 1.2 */ void writeSQL(SQLOutput stream) throws SQLException; }