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25
26 /**
27 * Provides utility classes to allow serializable mappings between SQL types
28 * and data types in the Java programming language.
29 * <p> Standard JDBC <code>RowSet</code> implementations may use these utility
30 * classes to
31 * assist in the serialization of disconnected <code>RowSet</code> objects.
32 * This is useful
33 * when transmitting a disconnected <code>RowSet</code> object over the wire to
34 * a different VM or across layers within an application.<br>
35 * </p>
36 *
37 * <h3>1.0 SerialArray</h3>
38 * A serializable mapping in the Java programming language of an SQL ARRAY
39 * value. <br>
40 * <br>
41 * The <code>SerialArray</code> class provides a constructor for creating a <code>SerialArray</code>
42 * instance from an Array object, methods for getting the base type and
43 * the SQL name for the base type, and methods for copying all or part of a
44 * <code>SerialArray</code> object. <br>
45 *
46 * <h3>2.0 SerialBlob</h3>
47 * A serializable mapping in the Java programming language of an SQL BLOB
48 * value. <br>
49 * <br>
50 * The <code>SerialBlob</code>class provides a constructor for creating an instance
51 * from a Blob object. Note that the Blob object should have brought the SQL
52 * BLOB value's data over to the client before a <code>SerialBlob</code>object
53 * is constructed from it. The data of an SQL BLOB value can be materialized
54 * on the client as an array of bytes (using the method <code>Blob.getBytes</code>)
55 * or as a stream of uninterpreted bytes (using the method <code>Blob.getBinaryStream</code>).
56 * <br>
57 * <br>
58 * <code>SerialBlob</code> methods make it possible to make a copy of a <code>SerialBlob</code>
59 * object as an array of bytes or as a stream. They also make it possible
60 * to locate a given pattern of bytes or a <code>Blob</code> object within a <code>SerialBlob</code>
61 * object. <br>
62 *
63 * <h3>3.0 SerialClob</h3>
64 * A serializable mapping in the Java programming language of an SQL CLOB
65 * value. <br>
66 * <br>
67 * The <code>SerialClob</code> class provides a constructor for creating an instance
68 * from a <code>Clob</code> object. Note that the <code>Clob</code> object should have
69 * brought the SQL CLOB value's data over to the client before a <code>SerialClob</code>
70 * object is constructed from it. The data of an SQL CLOB value can be
71 * materialized on the client as a stream of Unicode characters. <br>
72 * <br>
73 * <code>SerialClob</code> methods make it possible to get a substring from a
74 * <code>SerialClob</code> object or to locate the start of a pattern of characters.
75 * <br>
76 *
77 * <h3>5.0 SerialDatalink</h3>
78 * A serializable mapping in the Java programming language of an SQL DATALINK
79 * value. A DATALINK value references a file outside of the underlying data source
80 * that the originating data source manages. <br>
81 * <br>
82 * <code>RowSet</code> implementations can use the method <code>RowSet.getURL()</code> to retrieve
83 * a <code>java.net.URL</code> object, which can be used to manipulate the external data.
84 * <br>
85 * <br>
86 * <code> java.net.URL url = rowset.getURL(1);</code><br>
87 *
88 * <h3>6.0 SerialJavaObject</h3>
89 * A serializable mapping in the Java programming language of an SQL JAVA_OBJECT
90 * value. Assuming the Java object instance implements the Serializable interface,
91 * this simply wraps the serialization process. <br>
92 * <br>
93 * If however, the serialization is not possible in the case where the Java
94 * object is not immediately serializable, this class will attempt to serialize
95 * all non static members to permit the object instance state to be serialized.
96 * Static or transient fields cannot be serialized and attempting to do so
97 * will result in a <code>SerialException</code> being thrown. <br>
98 *
99 * <h3>7.0 SerialRef</h3>
100 * A serializable mapping between the SQL REF type and the Java programming
101 * language. <br>
102 * <br>
103 * The <code>SerialRef</code> class provides a constructor for creating a <code>SerialRef</code>
104 * instance from a <code>Ref</code> type and provides methods for getting
105 * and setting the <code>Ref</code> object type. <br>
106 *
107 * <h3>8.0 SerialStruct</h3>
108 * A serializable mapping in the Java programming language of an SQL structured
109 * type. Each attribute that is not already serializable is mapped to a serializable
110 * form, and if an attribute is itself a structured type, each of its attributes
111 * that is not already serializable is mapped to a serializable form. <br>
112 * <br>
113 * In addition, if a <code>Map</code> object is passed to one of the constructors or
114 * to the method <code>getAttributes</code>, the structured type is custom mapped
115 * according to the mapping specified in the <code>Map</code> object.
116 * <br>
117 * The <code>SerialStruct</code> class provides a constructor for creating an
118 * instance from a <code>Struct</code> object, a method for retrieving the SQL
119 * type name of the SQL structured type in the database, and methods for retrieving
120 * its attribute values. <br>
121 *
122 * <h3>9.0 SQLInputImpl</h3>
123 * An input stream used for custom mapping user-defined types (UDTs). An
124 * <code>SQLInputImpl</code> object is an input stream that contains a stream of
125 * values that are
126 * the attributes of a UDT. This class is used by the driver behind the scenes
127 * when the method <code>getObject</code> is called on an SQL structured or distinct
128 * type that has a custom mapping; a programmer never invokes <code>SQLInputImpl</code>
129 * methods directly. <br>
130 * <br>
131 * The <code>SQLInputImpl</code> class provides a set of reader methods
132 * analogous to the <code>ResultSet</code> getter methods. These methods make it
133 * possible to read the values in an <code>SQLInputImpl</code> object. The method
134 * <code>wasNull</code> is used to determine whether the last value read was SQL NULL.
135 * <br>
136 * <br>
137 * When a constructor or getter method that takes a <code>Map</code> object is called,
138 * the JDBC driver calls the method
139 * <code>SQLData.getSQLType</code> to determine the SQL type of the UDT being custom
140 * mapped. The driver creates an instance of <code>SQLInputImpl</code>, populating it with
141 * the attributes of the UDT. The driver then passes the input stream to the
142 * method <code>SQLData.readSQL</code>, which in turn calls the <code>SQLInputImpl</code>
143 * methods to read the attributes from the input stream. <br>
144 *
145 * <h3>10.0 SQLOutputImpl</h3>
146 * The output stream for writing the attributes of a custom mapped user-defined
147 * type (UDT) back to the database. The driver uses this interface internally,
148 * and its methods are never directly invoked by an application programmer.
149 * <br>
150 * <br>
151 * When an application calls the method <code>PreparedStatement.setObject</code>, the
152 * driver checks to see whether the value to be written is a UDT with a custom
153 * mapping. If it is, there will be an entry in a type map containing the Class
154 * object for the class that implements <code>SQLData</code> for this UDT. If the
155 * value to be written is an instance of <code>SQLData</code>, the driver will
156 * create an instance of <code>SQLOutputImpl</code> and pass it to the method
157 * <code>SQLData.writeSQL</code>.
158 * The method <code>writeSQL</code> in turn calls the appropriate <code>SQLOutputImpl</code>
159 * writer methods to write data from the <code>SQLData</code> object to the
160 * <code>SQLOutputImpl</code>
161 * output stream as the representation of an SQL user-defined type.
162 *
163 * <h3>Custom Mapping</h3>
164 * The JDBC API provides mechanisms for mapping an SQL structured type or DISTINCT
165 * type to the Java programming language. Typically, a structured type is mapped
166 * to a class, and its attributes are mapped to fields in the class.
167 * (A DISTINCT type can thought of as having one attribute.) However, there are
168 * many other possibilities, and there may be any number of different mappings.
169 * <P>
170 * A programmer defines the mapping by implementing the interface <code>SQLData</code>.
171 * For example, if an SQL structured type named AUTHORS has the attributes NAME,
172 * TITLE, and PUBLISHER, it could be mapped to a Java class named Authors. The
173 * Authors class could have the fields name, title, and publisher, to which the
174 * attributes of AUTHORS are mapped. In such a case, the implementation of
175 * <code>SQLData</code> could look like the following:
176 * <PRE>
177 * public class Authors implements SQLData {
178 * public String name;
179 * public String title;
180 * public String publisher;
181 *
182 * private String sql_type;
183 * public String getSQLTypeName() {
184 * return sql_type;
185 * }
186 *
187 * public void readSQL(SQLInput stream, String type)
188 * throws SQLException {
189 * sql_type = type;
190 * name = stream.readString();
191 * title = stream.readString();
192 * publisher = stream.readString();
193 * }
194 *
195 * public void writeSQL(SQLOutput stream) throws SQLException {
196 * stream.writeString(name);
197 * stream.writeString(title);
198 * stream.writeString(publisher);
199 * }
200 * }
201 * </PRE>
202 *
203 * A <code>java.util.Map</code> object is used to associate the SQL structured
204 * type with its mapping to the class <code>Authors</code>. The following code fragment shows
205 * how a <code>Map</code> object might be created and given an entry associating
206 * <code>AUTHORS</code> and <code>Authors</code>.
207 * <PRE>
208 * java.util.Map map = new java.util.HashMap();
209 * map.put("SCHEMA_NAME.AUTHORS", Class.forName("Authors");
210 * </PRE>
211 *
212 * The <code>Map</code> object <i>map</i> now contains an entry with the
213 * fully qualified name of the SQL structured type and the <code>Class</code>
214 * object for the class <code>Authors</code>. It can be passed to a method
215 * to tell the driver how to map <code>AUTHORS</code> to <code>Authors</code>.
216 * <P>
217 * For a disconnected <code>RowSet</code> object, custom mapping can be done
218 * only when a <code>Map</code> object is passed to the method or constructor
219 * that will be doing the custom mapping. The situation is different for
220 * connected <code>RowSet</code> objects because they maintain a connection
221 * with the data source. A method that does custom mapping and is called by
222 * a disconnected <code>RowSet</code> object may use the <code>Map</code>
223 * object that is associated with the <code>Connection</code> object being
224 * used. So, in other words, if no map is specified, the connection's type
225 * map can be used by default.
226 */
227 package javax.sql.rowset.serial;