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 }
Save This Page