1 /*
2 * Copyright (c) 2003, 2013, 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 public class SerialDatalink implements Serializable, Cloneable {
53
54 /**
55 * The extracted URL field retrieved from the DATALINK field.
56 * @serial
57 */
58 private URL url;
59
60 /**
61 * The SQL type of the elements in this <code>SerialDatalink</code>
62 * object. The type is expressed as one of the contants from the
63 * class <code>java.sql.Types</code>.
64 * @serial
65 */
66 private int baseType;
67
68 /**
69 * The type name used by the DBMS for the elements in the SQL
70 * <code>DATALINK</code> value that this SerialDatalink object
71 * represents.
72 * @serial
73 */
74 private String baseTypeName;
75
76 /**
77 * Constructs a new <code>SerialDatalink</code> object from the given
78 * <code>java.net.URL</code> object.
79 * <P>
80 * @param url the {@code URL} to create the {@code SerialDataLink} from
81 * @throws SerialException if url parameter is a null
82 */
83 public SerialDatalink(URL url) throws SerialException {
84 if (url == null) {
85 throw new SerialException("Cannot serialize empty URL instance");
86 }
87 this.url = url;
88 }
89
90 /**
91 * Returns a new URL that is a copy of this <code>SerialDatalink</code>
92 * object.
93 *
94 * @return a copy of this <code>SerialDatalink</code> object as a
95 * <code>URL</code> object in the Java programming language.
96 * @throws SerialException if the <code>URL</code> object cannot be de-serialized
97 */
98 public URL getDatalink() throws SerialException {
99
100 URL aURL = null;
101
102 try {
103 aURL = new URL((this.url).toString());
104 } catch (java.net.MalformedURLException e) {
105 throw new SerialException("MalformedURLException: " + e.getMessage());
106 }
107 return aURL;
108 }
109
110 /**
111 * Compares this {@code SerialDatalink} to the specified object.
112 * The result is {@code true} if and only if the argument is not
113 * {@code null} and is a {@code SerialDatalink} object whose URL is
114 * identical to this object's URL
115 *
116 * @param obj The object to compare this {@code SerialDatalink} against
117 *
118 * @return {@code true} if the given object represents a {@code SerialDatalink}
119 * equivalent to this SerialDatalink, {@code false} otherwise
120 *
121 */
122 public boolean equals(Object obj) {
123 if (this == obj) {
124 return true;
125 }
126 if (obj instanceof SerialDatalink) {
127 SerialDatalink sdl = (SerialDatalink) obj;
128 return url.equals(sdl.url);
129 }
130 return false;
131 }
132
133 /**
134 * Returns a hash code for this {@code SerialDatalink}. The hash code for a
135 * {@code SerialDatalink} object is taken as the hash code of
136 * the {@code URL} it stores
137 *
138 * @return a hash code value for this object.
139 */
140 public int hashCode() {
141 return 31 + url.hashCode();
142 }
143
144 /**
145 * Returns a clone of this {@code SerialDatalink}.
146 *
147 * @return a clone of this SerialDatalink
148 */
149 public Object clone() {
150 try {
151 SerialDatalink sdl = (SerialDatalink) super.clone();
152 return sdl;
153 } catch (CloneNotSupportedException ex) {
154 // this shouldn't happen, since we are Cloneable
155 throw new InternalError();
156 }
157 }
158
159 /**
160 * readObject and writeObject are called to restore the state
161 * of the {@code SerialDatalink}
162 * from a stream. Note: we leverage the default Serialized form
163 */
164
165 /**
166 * The identifier that assists in the serialization of this
167 * {@code SerialDatalink} object.
168 */
169 static final long serialVersionUID = 2826907821828733626L;
170 }