1 /*
2 * Copyright (c) 2003, 2012, 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.io.*;
29 import java.lang.reflect.*;
30 import java.util.Arrays;
31 import java.util.Vector;
32 import javax.sql.rowset.RowSetWarning;
33
34 /**
35 * A serializable mapping in the Java programming language of an SQL
36 * <code>JAVA_OBJECT</code> value. Assuming the Java object
37 * implements the <code>Serializable</code> interface, this class simply wraps the
38 * serialization process.
39 * <P>
40 * If however, the serialization is not possible because
41 * the Java object is not immediately serializable, this class will
42 * attempt to serialize all non-static members to permit the object
43 * state to be serialized.
44 * Static or transient fields cannot be serialized; an attempt to serialize
45 * them will result in a <code>SerialException</code> object being thrown.
46 *
47 * @author Jonathan Bruce
48 */
49 public class SerialJavaObject implements Serializable, Cloneable {
50
51 /**
52 * Placeholder for object to be serialized.
53 */
54 private Object obj;
55
56
57 /**
58 * Placeholder for all fields in the <code>JavaObject</code> being serialized.
59 */
60 private transient Field[] fields;
61
62 /**
63 * Constructor for <code>SerialJavaObject</code> helper class.
64 * <p>
65 *
66 * @param obj the Java <code>Object</code> to be serialized
67 * @throws SerialException if the object is found not to be serializable
68 */
69 public SerialJavaObject(Object obj) throws SerialException {
70
71 // if any static fields are found, an exception
72 // should be thrown
73
74
75 // get Class. Object instance should always be available
76 Class<?> c = obj.getClass();
77
78 // determine if object implements Serializable i/f
79 if (!(obj instanceof java.io.Serializable)) {
80 setWarning(new RowSetWarning("Warning, the object passed to the constructor does not implement Serializable"));
81 }
82
83 // can only determine public fields (obviously). If
84 // any of these are static, this should invalidate
85 // the action of attempting to persist these fields
86 // in a serialized form
87
88 boolean anyStaticFields = false;
89 fields = c.getFields();
90
91 for (int i = 0; i < fields.length; i++ ) {
92 if ( fields[i].getModifiers() == Modifier.STATIC ) {
93 anyStaticFields = true;
94 }
95 }
96
97
98 if (anyStaticFields) {
99 throw new SerialException("Located static fields in " +
100 "object instance. Cannot serialize");
101 }
102
103 this.obj = obj;
104 }
105
106 /**
107 * Returns an <code>Object</code> that is a copy of this <code>SerialJavaObject</code>
108 * object.
109 *
110 * @return a copy of this <code>SerialJavaObject</code> object as an
111 * <code>Object</code> in the Java programming language
112 * @throws SerialException if the instance is corrupt
113 */
114 public Object getObject() throws SerialException {
115 return this.obj;
116 }
117
118 /**
119 * Returns an array of <code>Field</code> objects that contains each
120 * field of the object that this helper class is serializing.
121 *
122 * @return an array of <code>Field</code> objects
123 * @throws SerialException if an error is encountered accessing
124 * the serialized object
125 */
126 public Field[] getFields() throws SerialException {
127 if (fields != null) {
128 Class<?> c = this.obj.getClass();
129 return c.getFields();
130 } else {
131 throw new SerialException("SerialJavaObject does not contain" +
132 " a serialized object instance");
133 }
134 }
135
136 /**
137 * The identifier that assists in the serialization of this
138 * <code>SerialJavaObject</code> object.
139 */
140 static final long serialVersionUID = -1465795139032831023L;
141
142 /**
143 * A container for the warnings issued on this <code>SerialJavaObject</code>
144 * object. When there are multiple warnings, each warning is chained to the
145 * previous warning.
146 */
147 Vector<RowSetWarning> chain;
148
149 /**
150 * Compares this SerialJavaObject to the specified object.
151 * The result is {@code true} if and only if the argument
152 * is not {@code null} and is a {@code SerialJavaObject}
153 * object that is identical to this object
154 *
155 * @param o The object to compare this {@code SerialJavaObject} against
156 *
157 * @return {@code true} if the given object represents a {@code SerialJavaObject}
158 * equivalent to this SerialJavaObject, {@code false} otherwise
159 *
160 */
161 public boolean equals(Object o) {
162 if (this == o) {
163 return true;
164 }
165 if (o instanceof SerialJavaObject) {
166 if(this.obj.equals( ((SerialJavaObject)o).obj))
167 return true;
168 }
169 return false;
170 }
171
172 /**
173 * Returns a hash code for this SerialJavaObject. The hash code for a
174 * {@code SerialJavaObject} object is taken as the hash code of
175 * the {@code Object} it stores
176 *
177 * @return a hash code value for this object.
178 */
179 public int hashCode() {
180 return 31 + obj.hashCode();
181 }
182
183 /**
184 * Returns a clone of this {@code SerialJavaObject}.
185 *
186 * @return a clone of this SerialJavaObject
187 */
188
189 public Object clone() {
190 try {
191 SerialJavaObject sjo = (SerialJavaObject) super.clone();
192 sjo.fields = Arrays.copyOf(fields, fields.length);
193 if (chain != null)
194 sjo.chain = new Vector<RowSetWarning>(chain);
195 return sjo;
196 } catch (CloneNotSupportedException ex) {
197 // this shouldn't happen, since we are Cloneable
198 throw new InternalError();
199 }
200 }
201
202 /**
203 * Registers the given warning.
204 */
205 private void setWarning(RowSetWarning e) {
206 if (chain == null) {
207 chain = new Vector<RowSetWarning>();
208 }
209 chain.add(e);
210 }
211
212 /**
213 * readObject is called to restore the state of the {@code SerialJavaObject}
214 * from a stream.
215 */
216 private void readObject(ObjectInputStream s)
217 throws IOException, ClassNotFoundException {
218
219 ObjectInputStream.GetField fields1 = s.readFields();
220 @SuppressWarnings("unchecked")
221 Vector<RowSetWarning> tmp = (Vector<RowSetWarning>)fields1.get("chain", null);
222 if (tmp != null)
223 chain = new Vector<RowSetWarning>(tmp);
224 obj = fields1.get("obj", null);
225 fields = obj.getClass().getFields();
226 }
227
228 /**
229 * writeObject is called to save the state of the {@code SerialJavaObject}
230 * to a stream.
231 */
232 private void writeObject(ObjectOutputStream s)
233 throws IOException {
234 ObjectOutputStream.PutField fields = s.putFields();
235 fields.put("obj", obj);
236 fields.put("chain", chain);
237 s.writeFields();
238 }
239 }