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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
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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
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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 }