1 /*
2 * Copyright (c) 2003, 2014, Oracle and/or its affiliates. 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. 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
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.sql.rowset.serial;
27
28 import java.sql.*;
29 import java.io.*;
30 import java.net.URL;
31
32
33 /**
34 * A serialized mapping in the Java programming language of an SQL
35 * <code>DATALINK</code> value. A <code>DATALINK</code> value
36 * references a file outside of the underlying data source that the
37 * data source manages.
38 * <P>
39 * <code>RowSet</code> implementations can use the method <code>RowSet.getURL</code>
40 * to retrieve a <code>java.net.URL</code> object, which can be used
41 * to manipulate the external data.
42 * <pre>
43 * java.net.URL url = rowset.getURL(1);
44 * </pre>
45 *
46 * <h3> Thread safety </h3>
47 *
48 * A SerialDatalink is not safe for use by multiple concurrent threads. If a
49 * SerialDatalink is to be used by more than one thread then access to the
50 * SerialDatalink should be controlled by appropriate synchronization.
51 *
52 * @since 1.5
53 */
54 public class SerialDatalink implements Serializable, Cloneable {
55
56 /**
57 * The extracted URL field retrieved from the DATALINK field.
58 * @serial
59 */
60 private URL url;
61
62 /**
63 * The SQL type of the elements in this <code>SerialDatalink</code>
64 * object. The type is expressed as one of the constants from the
65 * class <code>java.sql.Types</code>.
66 * @serial
67 */
68 private int baseType;
69
70 /**
71 * The type name used by the DBMS for the elements in the SQL
72 * <code>DATALINK</code> value that this SerialDatalink object
73 * represents.
74 * @serial
75 */
76 private String baseTypeName;
77
78 /**
79 * Constructs a new <code>SerialDatalink</code> object from the given
80 * <code>java.net.URL</code> object.
81 *
82 * @param url the {@code URL} to create the {@code SerialDataLink} from
83 * @throws SerialException if url parameter is a null
84 */
85 public SerialDatalink(URL url) throws SerialException {
86 if (url == null) {
87 throw new SerialException("Cannot serialize empty URL instance");
88 }
89 this.url = url;
90 }
91
92 /**
93 * Returns a new URL that is a copy of this <code>SerialDatalink</code>
94 * object.
95 *
96 * @return a copy of this <code>SerialDatalink</code> object as a
97 * <code>URL</code> object in the Java programming language.
98 * @throws SerialException if the <code>URL</code> object cannot be de-serialized
99 */
100 public URL getDatalink() throws SerialException {
101
102 URL aURL = null;
103
104 try {
105 aURL = new URL((this.url).toString());
106 } catch (java.net.MalformedURLException e) {
107 throw new SerialException("MalformedURLException: " + e.getMessage());
108 }
109 return aURL;
110 }
111
112 /**
113 * Compares this {@code SerialDatalink} to the specified object.
114 * The result is {@code true} if and only if the argument is not
115 * {@code null} and is a {@code SerialDatalink} object whose URL is
116 * identical to this object's URL
117 *
118 * @param obj The object to compare this {@code SerialDatalink} against
119 *
120 * @return {@code true} if the given object represents a {@code SerialDatalink}
121 * equivalent to this SerialDatalink, {@code false} otherwise
122 *
123 */
124 public boolean equals(Object obj) {
125 if (this == obj) {
126 return true;
127 }
128 if (obj instanceof SerialDatalink) {
129 SerialDatalink sdl = (SerialDatalink) obj;
130 return url.equals(sdl.url);
131 }
132 return false;
133 }
134
135 /**
136 * Returns a hash code for this {@code SerialDatalink}. The hash code for a
137 * {@code SerialDatalink} object is taken as the hash code of
138 * the {@code URL} it stores
139 *
140 * @return a hash code value for this object.
141 */
142 public int hashCode() {
143 return 31 + url.hashCode();
144 }
145
146 /**
147 * Returns a clone of this {@code SerialDatalink}.
148 *
149 * @return a clone of this SerialDatalink
150 */
151 public Object clone() {
152 try {
153 SerialDatalink sdl = (SerialDatalink) super.clone();
154 return sdl;
155 } catch (CloneNotSupportedException ex) {
156 // this shouldn't happen, since we are Cloneable
157 throw new InternalError();
158 }
159 }
160
161 /**
162 * readObject and writeObject are called to restore the state
163 * of the {@code SerialDatalink}
164 * from a stream. Note: we leverage the default Serialized form
165 */
166
167 /**
168 * The identifier that assists in the serialization of this
169 * {@code SerialDatalink} object.
170 */
171 static final long serialVersionUID = 2826907821828733626L;
172 }