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.io.*;
29 import java.lang.reflect.*;
30 import java.util.Arrays;
31 import java.util.Vector;
32 import javax.sql.rowset.RowSetWarning;
33 import sun.reflect.CallerSensitive;
34 import sun.reflect.Reflection;
35 import sun.reflect.misc.ReflectUtil;
36
37 /**
38 * A serializable mapping in the Java programming language of an SQL
39 * <code>JAVA_OBJECT</code> value. Assuming the Java object
40 * implements the <code>Serializable</code> interface, this class simply wraps the
41 * serialization process.
42 * <P>
43 * If however, the serialization is not possible because
44 * the Java object is not immediately serializable, this class will
45 * attempt to serialize all non-static members to permit the object
46 * state to be serialized.
47 * Static or transient fields cannot be serialized; an attempt to serialize
48 * them will result in a <code>SerialException</code> object being thrown.
49 *
50 * <h3> Thread safety </h3>
51 *
52 * A SerialJavaObject is not safe for use by multiple concurrent threads. If a
53 * SerialJavaObject is to be used by more than one thread then access to the
54 * SerialJavaObject should be controlled by appropriate synchronization.
55 *
56 * @author Jonathan Bruce
57 */
58 public class SerialJavaObject implements Serializable, Cloneable {
59
60 /**
61 * Placeholder for object to be serialized.
62 */
63 private Object obj;
64
65
66 /**
67 * Placeholder for all fields in the <code>JavaObject</code> being serialized.
68 */
69 private transient Field[] fields;
70
71 /**
72 * Constructor for <code>SerialJavaObject</code> helper class.
73 * <p>
74 *
75 * @param obj the Java <code>Object</code> to be serialized
76 * @throws SerialException if the object is found not to be serializable
77 */
78 public SerialJavaObject(Object obj) throws SerialException {
79
80 // if any static fields are found, an exception
81 // should be thrown
82
83
84 // get Class. Object instance should always be available
85 Class<?> c = obj.getClass();
86
87 // determine if object implements Serializable i/f
88 if (!(obj instanceof java.io.Serializable)) {
89 setWarning(new RowSetWarning("Warning, the object passed to the constructor does not implement Serializable"));
90 }
91
92 // can only determine public fields (obviously). If
93 // any of these are static, this should invalidate
94 // the action of attempting to persist these fields
95 // in a serialized form
96 fields = c.getFields();
97
98 if (hasStaticFields(fields)) {
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 * @throws SecurityException If a security manager, <i>s</i>, is present
126 * and the caller's class loader is not the same as or an
127 * ancestor of the class loader for the class of the
128 * {@linkplain #getObject object} being serialized
129 * and invocation of {@link SecurityManager#checkPackageAccess
130 * s.checkPackageAccess()} denies access to the package
131 * of that class.
132 * @see Class#getFields
133 */
134 @CallerSensitive
135 public Field[] getFields() throws SerialException {
136 if (fields != null) {
137 Class<?> c = this.obj.getClass();
138 SecurityManager sm = System.getSecurityManager();
139 if (sm != null) {
140 /*
141 * Check if the caller is allowed to access the specified class's package.
142 * If access is denied, throw a SecurityException.
143 */
144 Class<?> caller = sun.reflect.Reflection.getCallerClass();
145 if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(),
146 c.getClassLoader())) {
147 ReflectUtil.checkPackageAccess(c);
148 }
149 }
150 return c.getFields();
151 } else {
152 throw new SerialException("SerialJavaObject does not contain" +
153 " a serialized object instance");
154 }
155 }
156
157 /**
158 * The identifier that assists in the serialization of this
159 * <code>SerialJavaObject</code> object.
160 */
161 static final long serialVersionUID = -1465795139032831023L;
162
163 /**
164 * A container for the warnings issued on this <code>SerialJavaObject</code>
165 * object. When there are multiple warnings, each warning is chained to the
166 * previous warning.
167 */
168 Vector<RowSetWarning> chain;
169
170 /**
171 * Compares this SerialJavaObject to the specified object.
172 * The result is {@code true} if and only if the argument
173 * is not {@code null} and is a {@code SerialJavaObject}
174 * object that is identical to this object
175 *
176 * @param o The object to compare this {@code SerialJavaObject} against
177 *
178 * @return {@code true} if the given object represents a {@code SerialJavaObject}
179 * equivalent to this SerialJavaObject, {@code false} otherwise
180 *
181 */
182 public boolean equals(Object o) {
183 if (this == o) {
184 return true;
185 }
186 if (o instanceof SerialJavaObject) {
187 SerialJavaObject sjo = (SerialJavaObject) o;
188 return obj.equals(sjo.obj);
189 }
190 return false;
191 }
192
193 /**
194 * Returns a hash code for this SerialJavaObject. The hash code for a
195 * {@code SerialJavaObject} object is taken as the hash code of
196 * the {@code Object} it stores
197 *
198 * @return a hash code value for this object.
199 */
200 public int hashCode() {
201 return 31 + obj.hashCode();
202 }
203
204 /**
205 * Returns a clone of this {@code SerialJavaObject}.
206 *
207 * @return a clone of this SerialJavaObject
208 */
209
210 public Object clone() {
211 try {
212 SerialJavaObject sjo = (SerialJavaObject) super.clone();
213 sjo.fields = Arrays.copyOf(fields, fields.length);
214 if (chain != null)
215 sjo.chain = new Vector<>(chain);
216 return sjo;
217 } catch (CloneNotSupportedException ex) {
218 // this shouldn't happen, since we are Cloneable
219 throw new InternalError();
220 }
221 }
222
223 /**
224 * Registers the given warning.
225 */
226 private void setWarning(RowSetWarning e) {
227 if (chain == null) {
228 chain = new Vector<>();
229 }
230 chain.add(e);
231 }
232
233 /**
234 * readObject is called to restore the state of the {@code SerialJavaObject}
235 * from a stream.
236 */
237 private void readObject(ObjectInputStream s)
238 throws IOException, ClassNotFoundException {
239
240 ObjectInputStream.GetField fields1 = s.readFields();
241 @SuppressWarnings("unchecked")
242 Vector<RowSetWarning> tmp = (Vector<RowSetWarning>)fields1.get("chain", null);
243 if (tmp != null)
244 chain = new Vector<>(tmp);
245
246 obj = fields1.get("obj", null);
247 if (obj != null) {
248 fields = obj.getClass().getFields();
249 if(hasStaticFields(fields))
250 throw new IOException("Located static fields in " +
251 "object instance. Cannot serialize");
252 } else {
253 throw new IOException("Object cannot be null!");
254 }
255
256 }
257
258 /**
259 * writeObject is called to save the state of the {@code SerialJavaObject}
260 * to a stream.
261 */
262 private void writeObject(ObjectOutputStream s)
263 throws IOException {
264 ObjectOutputStream.PutField fields = s.putFields();
265 fields.put("obj", obj);
266 fields.put("chain", chain);
267 s.writeFields();
268 }
269
270 /*
271 * Check to see if there are any Static Fields in this object
272 */
273 private static boolean hasStaticFields(Field[] fields) {
274 for (Field field : fields) {
275 if ( field.getModifiers() == Modifier.STATIC) {
276 return true;
277 }
278 }
279 return false;
280 }
281 }