J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1998-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.sql; |
| 27 | |
| 28 | /** |
| 29 | * The interface used for the custom mapping of an SQL user-defined type (UDT) to |
| 30 | * a class in the Java programming language. The class object for a class |
| 31 | * implementing the <code>SQLData</code> interface will be entered in the |
| 32 | * appropriate <code>Connection</code> object's type map along with the SQL |
| 33 | * name of the UDT for which it is a custom mapping. |
| 34 | * <P> |
| 35 | * Typically, a <code>SQLData</code> implementation |
| 36 | * will define a field for each attribute of an SQL structured type or a |
| 37 | * single field for an SQL <code>DISTINCT</code> type. When the UDT is |
| 38 | * retrieved from a data source with the <code>ResultSet.getObject</code> |
| 39 | * method, it will be mapped as an instance of this class. A programmer |
| 40 | * can operate on this class instance just as on any other object in the |
| 41 | * Java programming language and then store any changes made to it by |
| 42 | * calling the <code>PreparedStatement.setObject</code> method, |
| 43 | * which will map it back to the SQL type. |
| 44 | * <p> |
| 45 | * It is expected that the implementation of the class for a custom |
| 46 | * mapping will be done by a tool. In a typical implementation, the |
| 47 | * programmer would simply supply the name of the SQL UDT, the name of |
| 48 | * the class to which it is being mapped, and the names of the fields to |
| 49 | * which each of the attributes of the UDT is to be mapped. The tool will use |
| 50 | * this information to implement the <code>SQLData.readSQL</code> and |
| 51 | * <code>SQLData.writeSQL</code> methods. The <code>readSQL</code> method |
| 52 | * calls the appropriate <code>SQLInput</code> methods to read |
| 53 | * each attribute from an <code>SQLInput</code> object, and the |
| 54 | * <code>writeSQL</code> method calls <code>SQLOutput</code> methods |
| 55 | * to write each attribute back to the data source via an |
| 56 | * <code>SQLOutput</code> object. |
| 57 | * <P> |
| 58 | * An application programmer will not normally call <code>SQLData</code> methods |
| 59 | * directly, and the <code>SQLInput</code> and <code>SQLOutput</code> methods |
| 60 | * are called internally by <code>SQLData</code> methods, not by application code. |
| 61 | * |
| 62 | * @since 1.2 |
| 63 | */ |
| 64 | public interface SQLData { |
| 65 | |
| 66 | /** |
| 67 | * Returns the fully-qualified |
| 68 | * name of the SQL user-defined type that this object represents. |
| 69 | * This method is called by the JDBC driver to get the name of the |
| 70 | * UDT instance that is being mapped to this instance of |
| 71 | * <code>SQLData</code>. |
| 72 | * |
| 73 | * @return the type name that was passed to the method <code>readSQL</code> |
| 74 | * when this object was constructed and populated |
| 75 | * @exception SQLException if there is a database access error |
| 76 | * @exception SQLFeatureNotSupportedException if the JDBC driver does not support |
| 77 | * this method |
| 78 | * @since 1.2 |
| 79 | */ |
| 80 | String getSQLTypeName() throws SQLException; |
| 81 | |
| 82 | /** |
| 83 | * Populates this object with data read from the database. |
| 84 | * The implementation of the method must follow this protocol: |
| 85 | * <UL> |
| 86 | * <LI>It must read each of the attributes or elements of the SQL |
| 87 | * type from the given input stream. This is done |
| 88 | * by calling a method of the input stream to read each |
| 89 | * item, in the order that they appear in the SQL definition |
| 90 | * of the type. |
| 91 | * <LI>The method <code>readSQL</code> then |
| 92 | * assigns the data to appropriate fields or |
| 93 | * elements (of this or other objects). |
| 94 | * Specifically, it must call the appropriate <i>reader</i> method |
| 95 | * (<code>SQLInput.readString</code>, <code>SQLInput.readBigDecimal</code>, |
| 96 | * and so on) method(s) to do the following: |
| 97 | * for a distinct type, read its single data element; |
| 98 | * for a structured type, read a value for each attribute of the SQL type. |
| 99 | * </UL> |
| 100 | * The JDBC driver initializes the input stream with a type map |
| 101 | * before calling this method, which is used by the appropriate |
| 102 | * <code>SQLInput</code> reader method on the stream. |
| 103 | * |
| 104 | * @param stream the <code>SQLInput</code> object from which to read the data for |
| 105 | * the value that is being custom mapped |
| 106 | * @param typeName the SQL type name of the value on the data stream |
| 107 | * @exception SQLException if there is a database access error |
| 108 | * @exception SQLFeatureNotSupportedException if the JDBC driver does not support |
| 109 | * this method |
| 110 | * @see SQLInput |
| 111 | * @since 1.2 |
| 112 | */ |
| 113 | void readSQL (SQLInput stream, String typeName) throws SQLException; |
| 114 | |
| 115 | /** |
| 116 | * Writes this object to the given SQL data stream, converting it back to |
| 117 | * its SQL value in the data source. |
| 118 | * The implementation of the method must follow this protocol:<BR> |
| 119 | * It must write each of the attributes of the SQL type |
| 120 | * to the given output stream. This is done by calling a |
| 121 | * method of the output stream to write each item, in the order that |
| 122 | * they appear in the SQL definition of the type. |
| 123 | * Specifically, it must call the appropriate <code>SQLOutput</code> writer |
| 124 | * method(s) (<code>writeInt</code>, <code>writeString</code>, and so on) |
| 125 | * to do the following: for a Distinct Type, write its single data element; |
| 126 | * for a Structured Type, write a value for each attribute of the SQL type. |
| 127 | * |
| 128 | * @param stream the <code>SQLOutput</code> object to which to write the data for |
| 129 | * the value that was custom mapped |
| 130 | * @exception SQLException if there is a database access error |
| 131 | * @exception SQLFeatureNotSupportedException if the JDBC driver does not support |
| 132 | * this method |
| 133 | * @see SQLOutput |
| 134 | * @since 1.2 |
| 135 | */ |
| 136 | void writeSQL (SQLOutput stream) throws SQLException; |
| 137 | } |