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.lang.reflect.*;
31 import java.util.Arrays;
32
33
34 /**
35 * A serialized mapping in the Java programming language of an SQL
36 * <code>BLOB</code> value.
37 * <P>
38 * The <code>SerialBlob</code> class provides a constructor for creating
39 * an instance from a <code>Blob</code> object. Note that the
40 * <code>Blob</code>
41 * object should have brought the SQL <code>BLOB</code> value's data over
42 * to the client before a <code>SerialBlob</code> object
43 * is constructed from it. The data of an SQL <code>BLOB</code> value can
44 * be materialized on the client as an array of bytes (using the method
45 * <code>Blob.getBytes</code>) or as a stream of uninterpreted bytes
46 * (using the method <code>Blob.getBinaryStream</code>).
47 * <P>
48 * <code>SerialBlob</code> methods make it possible to make a copy of a
49 * <code>SerialBlob</code> object as an array of bytes or as a stream.
50 * They also make it possible to locate a given pattern of bytes or a
51 * <code>Blob</code> object within a <code>SerialBlob</code> object
52 * and to update or truncate a <code>Blob</code> object.
53 *
54 * <h3> Thread safety </h3>
55 *
56 * <p> A SerialBlob is not safe for use by multiple concurrent threads. If a
57 * SerialBlob is to be used by more than one thread then access to the SerialBlob
58 * should be controlled by appropriate synchronization.
59 *
60 * @author Jonathan Bruce
61 */
62 public class SerialBlob implements Blob, Serializable, Cloneable {
63
64 /**
65 * A serialized array of uninterpreted bytes representing the
66 * value of this <code>SerialBlob</code> object.
67 * @serial
68 */
69 private byte buf[];
70
71 /**
72 * The internal representation of the <code>Blob</code> object on which this
73 * <code>SerialBlob</code> object is based.
74 */
75 private Blob blob;
76
77 /**
78 * The number of bytes in this <code>SerialBlob</code> object's
79 * array of bytes.
80 * @serial
81 */
82 private long len;
83
84 /**
85 * The original number of bytes in this <code>SerialBlob</code> object's
86 * array of bytes when it was first established.
87 * @serial
88 */
89 private long origLen;
90
91 /**
92 * Constructs a <code>SerialBlob</code> object that is a serialized version of
93 * the given <code>byte</code> array.
94 * <p>
95 * The new <code>SerialBlob</code> object is initialized with the data from the
96 * <code>byte</code> array, thus allowing disconnected <code>RowSet</code>
97 * objects to establish serialized <code>Blob</code> objects without
98 * touching the data source.
99 *
100 * @param b the <code>byte</code> array containing the data for the
101 * <code>Blob</code> object to be serialized
102 * @throws SerialException if an error occurs during serialization
103 * @throws SQLException if a SQL errors occurs
104 */
105 public SerialBlob(byte[] b) throws SerialException, SQLException {
106
107 len = b.length;
108 buf = new byte[(int)len];
109 for(int i = 0; i < len; i++) {
110 buf[i] = b[i];
111 }
112 origLen = len;
113 }
114
115
116 /**
117 * Constructs a <code>SerialBlob</code> object that is a serialized
118 * version of the given <code>Blob</code> object.
119 * <P>
120 * The new <code>SerialBlob</code> object is initialized with the
121 * data from the <code>Blob</code> object; therefore, the
122 * <code>Blob</code> object should have previously brought the
123 * SQL <code>BLOB</code> value's data over to the client from
124 * the database. Otherwise, the new <code>SerialBlob</code> object
125 * will contain no data.
126 *
127 * @param blob the <code>Blob</code> object from which this
128 * <code>SerialBlob</code> object is to be constructed;
129 * cannot be null.
130 * @throws SerialException if an error occurs during serialization
131 * @throws SQLException if the <code>Blob</code> passed to this
132 * to this constructor is a <code>null</code>.
133 * @see java.sql.Blob
134 */
135 public SerialBlob (Blob blob) throws SerialException, SQLException {
136
137 if (blob == null) {
138 throw new SQLException("Cannot instantiate a SerialBlob " +
139 "object with a null Blob object");
140 }
141
142 len = blob.length();
143 buf = blob.getBytes(1, (int)len );
144 this.blob = blob;
145
146 //if ( len < 10240000)
147 // len = 10240000;
148 origLen = len;
149 }
150
151 /**
152 * Copies the specified number of bytes, starting at the given
153 * position, from this <code>SerialBlob</code> object to
154 * another array of bytes.
155 * <P>
156 * Note that if the given number of bytes to be copied is larger than
157 * the length of this <code>SerialBlob</code> object's array of
158 * bytes, the given number will be shortened to the array's length.
159 *
160 * @param pos the ordinal position of the first byte in this
161 * <code>SerialBlob</code> object to be copied;
162 * numbering starts at <code>1</code>; must not be less
163 * than <code>1</code> and must be less than or equal
164 * to the length of this <code>SerialBlob</code> object
165 * @param length the number of bytes to be copied
166 * @return an array of bytes that is a copy of a region of this
167 * <code>SerialBlob</code> object, starting at the given
168 * position and containing the given number of consecutive bytes
169 * @throws SerialException if the given starting position is out of bounds;
170 * if {@code free} had previously been called on this object
171 */
172 public byte[] getBytes(long pos, int length) throws SerialException {
173 isValid();
174 if (length > len) {
175 length = (int)len;
176 }
177
178 if (pos < 1 || len - pos < 0 ) {
179 throw new SerialException("Invalid arguments: position cannot be "
180 + "less than 1 or greater than the length of the SerialBlob");
181 }
182
183 pos--; // correct pos to array index
184
185 byte[] b = new byte[length];
186
187 for (int i = 0; i < length; i++) {
188 b[i] = this.buf[(int)pos];
189 pos++;
190 }
191 return b;
192 }
193
194 /**
195 * Retrieves the number of bytes in this <code>SerialBlob</code>
196 * object's array of bytes.
197 *
198 * @return a <code>long</code> indicating the length in bytes of this
199 * <code>SerialBlob</code> object's array of bytes
200 * @throws SerialException if an error occurs;
201 * if {@code free} had previously been called on this object
202 */
203 public long length() throws SerialException {
204 isValid();
205 return len;
206 }
207
208 /**
209 * Returns this <code>SerialBlob</code> object as an input stream.
210 * Unlike the related method, <code>setBinaryStream</code>,
211 * a stream is produced regardless of whether the <code>SerialBlob</code>
212 * was created with a <code>Blob</code> object or a <code>byte</code> array.
213 *
214 * @return a <code>java.io.InputStream</code> object that contains
215 * this <code>SerialBlob</code> object's array of bytes
216 * @throws SerialException if an error occurs;
217 * if {@code free} had previously been called on this object
218 * @see #setBinaryStream
219 */
220 public java.io.InputStream getBinaryStream() throws SerialException {
221 isValid();
222 InputStream stream = new ByteArrayInputStream(buf);
223 return stream;
224 }
225
226 /**
227 * Returns the position in this <code>SerialBlob</code> object where
228 * the given pattern of bytes begins, starting the search at the
229 * specified position.
230 *
231 * @param pattern the pattern of bytes for which to search
232 * @param start the position of the byte in this
233 * <code>SerialBlob</code> object from which to begin
234 * the search; the first position is <code>1</code>;
235 * must not be less than <code>1</code> nor greater than
236 * the length of this <code>SerialBlob</code> object
237 * @return the position in this <code>SerialBlob</code> object
238 * where the given pattern begins, starting at the specified
239 * position; <code>-1</code> if the pattern is not found
240 * or the given starting position is out of bounds; position
241 * numbering for the return value starts at <code>1</code>
242 * @throws SerialException if an error occurs when serializing the blob;
243 * if {@code free} had previously been called on this object
244 * @throws SQLException if there is an error accessing the <code>BLOB</code>
245 * value from the database
246 */
247 public long position(byte[] pattern, long start)
248 throws SerialException, SQLException {
249 isValid();
250 if (start < 1 || start > len) {
251 return -1;
252 }
253
254 int pos = (int)start-1; // internally Blobs are stored as arrays.
255 int i = 0;
256 long patlen = pattern.length;
257
258 while (pos < len) {
259 if (pattern[i] == buf[pos]) {
260 if (i + 1 == patlen) {
261 return (pos + 1) - (patlen - 1);
262 }
263 i++; pos++; // increment pos, and i
264 } else if (pattern[i] != buf[pos]) {
265 pos++; // increment pos only
266 }
267 }
268 return -1; // not found
269 }
270
271 /**
272 * Returns the position in this <code>SerialBlob</code> object where
273 * the given <code>Blob</code> object begins, starting the search at the
274 * specified position.
275 *
276 * @param pattern the <code>Blob</code> object for which to search;
277 * @param start the position of the byte in this
278 * <code>SerialBlob</code> object from which to begin
279 * the search; the first position is <code>1</code>;
280 * must not be less than <code>1</code> nor greater than
281 * the length of this <code>SerialBlob</code> object
282 * @return the position in this <code>SerialBlob</code> object
283 * where the given <code>Blob</code> object begins, starting
284 * at the specified position; <code>-1</code> if the pattern is
285 * not found or the given starting position is out of bounds;
286 * position numbering for the return value starts at <code>1</code>
287 * @throws SerialException if an error occurs when serializing the blob;
288 * if {@code free} had previously been called on this object
289 * @throws SQLException if there is an error accessing the <code>BLOB</code>
290 * value from the database
291 */
292 public long position(Blob pattern, long start)
293 throws SerialException, SQLException {
294 isValid();
295 return position(pattern.getBytes(1, (int)(pattern.length())), start);
296 }
297
298 /**
299 * Writes the given array of bytes to the <code>BLOB</code> value that
300 * this <code>Blob</code> object represents, starting at position
301 * <code>pos</code>, and returns the number of bytes written.
302 *
303 * @param pos the position in the SQL <code>BLOB</code> value at which
304 * to start writing. The first position is <code>1</code>;
305 * must not be less than <code>1</code> nor greater than
306 * the length of this <code>SerialBlob</code> object.
307 * @param bytes the array of bytes to be written to the <code>BLOB</code>
308 * value that this <code>Blob</code> object represents
309 * @return the number of bytes written
310 * @throws SerialException if there is an error accessing the
311 * <code>BLOB</code> value; or if an invalid position is set; if an
312 * invalid offset value is set;
313 * if {@code free} had previously been called on this object
314 * @throws SQLException if there is an error accessing the <code>BLOB</code>
315 * value from the database
316 * @see #getBytes
317 */
318 public int setBytes(long pos, byte[] bytes)
319 throws SerialException, SQLException {
320 return (setBytes(pos, bytes, 0, bytes.length));
321 }
322
323 /**
324 * Writes all or part of the given <code>byte</code> array to the
325 * <code>BLOB</code> value that this <code>Blob</code> object represents
326 * and returns the number of bytes written.
327 * Writing starts at position <code>pos</code> in the <code>BLOB</code>
328 * value; <i>len</i> bytes from the given byte array are written.
329 *
330 * @param pos the position in the <code>BLOB</code> object at which
331 * to start writing. The first position is <code>1</code>;
332 * must not be less than <code>1</code> nor greater than
333 * the length of this <code>SerialBlob</code> object.
334 * @param bytes the array of bytes to be written to the <code>BLOB</code>
335 * value
336 * @param offset the offset in the <code>byte</code> array at which
337 * to start reading the bytes. The first offset position is
338 * <code>0</code>; must not be less than <code>0</code> nor greater
339 * than the length of the <code>byte</code> array
340 * @param length the number of bytes to be written to the
341 * <code>BLOB</code> value from the array of bytes <i>bytes</i>.
342 *
343 * @return the number of bytes written
344 * @throws SerialException if there is an error accessing the
345 * <code>BLOB</code> value; if an invalid position is set; if an
346 * invalid offset value is set; if number of bytes to be written
347 * is greater than the <code>SerialBlob</code> length; or the combined
348 * values of the length and offset is greater than the Blob buffer;
349 * if {@code free} had previously been called on this object
350 * @throws SQLException if there is an error accessing the <code>BLOB</code>
351 * value from the database.
352 * @see #getBytes
353 */
354 public int setBytes(long pos, byte[] bytes, int offset, int length)
355 throws SerialException, SQLException {
356
357 isValid();
358 if (offset < 0 || offset > bytes.length) {
359 throw new SerialException("Invalid offset in byte array set");
360 }
361
362 if (pos < 1 || pos > this.length()) {
363 throw new SerialException("Invalid position in BLOB object set");
364 }
365
366 if ((long)(length) > origLen) {
367 throw new SerialException("Buffer is not sufficient to hold the value");
368 }
369
370 if ((length + offset) > bytes.length) {
371 throw new SerialException("Invalid OffSet. Cannot have combined offset " +
372 "and length that is greater that the Blob buffer");
373 }
374
375 int i = 0;
376 pos--; // correct to array indexing
377 while ( i < length || (offset + i +1) < (bytes.length-offset) ) {
378 this.buf[(int)pos + i] = bytes[offset + i ];
379 i++;
380 }
381 return i;
382 }
383
384 /**
385 * Retrieves a stream that can be used to write to the <code>BLOB</code>
386 * value that this <code>Blob</code> object represents. The stream begins
387 * at position <code>pos</code>. This method forwards the
388 * <code>setBinaryStream()</code> call to the underlying <code>Blob</code> in
389 * the event that this <code>SerialBlob</code> object is instantiated with a
390 * <code>Blob</code>. If this <code>SerialBlob</code> is instantiated with
391 * a <code>byte</code> array, a <code>SerialException</code> is thrown.
392 *
393 * @param pos the position in the <code>BLOB</code> value at which
394 * to start writing
395 * @return a <code>java.io.OutputStream</code> object to which data can
396 * be written
397 * @throws SQLException if there is an error accessing the
398 * <code>BLOB</code> value
399 * @throws SerialException if the SerialBlob in not instantiated with a
400 * <code>Blob</code> object that supports <code>setBinaryStream()</code>;
401 * if {@code free} had previously been called on this object
402 * @see #getBinaryStream
403 */
404 public java.io.OutputStream setBinaryStream(long pos)
405 throws SerialException, SQLException {
406 isValid();
407 if (this.blob != null) {
408 return this.blob.setBinaryStream(pos);
409 } else {
410 throw new SerialException("Unsupported operation. SerialBlob cannot " +
411 "return a writable binary stream, unless instantiated with a Blob object " +
412 "that provides a setBinaryStream() implementation");
413 }
414 }
415
416 /**
417 * Truncates the <code>BLOB</code> value that this <code>Blob</code>
418 * object represents to be <code>len</code> bytes in length.
419 *
420 * @param length the length, in bytes, to which the <code>BLOB</code>
421 * value that this <code>Blob</code> object represents should be
422 * truncated
423 * @throws SerialException if there is an error accessing the Blob value;
424 * or the length to truncate is greater that the SerialBlob length;
425 * if {@code free} had previously been called on this object
426 */
427 public void truncate(long length) throws SerialException {
428
429 isValid();
430 if (length > len) {
431 throw new SerialException
432 ("Length more than what can be truncated");
433 } else if((int)length == 0) {
434 buf = new byte[0];
435 len = length;
436 } else {
437 len = length;
438 buf = this.getBytes(1, (int)len);
439 }
440 }
441
442
443 /**
444 * Returns an
445 * <code>InputStream</code> object that contains a partial
446 * {@code Blob} value, starting with the byte specified by pos, which is
447 * length bytes in length.
448 *
449 * @param pos the offset to the first byte of the partial value to be
450 * retrieved. The first byte in the {@code Blob} is at position 1
451 * @param length the length in bytes of the partial value to be retrieved
452 * @return
453 * <code>InputStream</code> through which the partial {@code Blob} value can
454 * be read.
455 * @throws SQLException if pos is less than 1 or if pos is greater than the
456 * number of bytes in the {@code Blob} or if pos + length is greater than
457 * the number of bytes in the {@code Blob}
458 * @throws SerialException if the {@code free} method had been previously
459 * called on this object
460 *
461 * @since 1.6
462 */
463 public InputStream getBinaryStream(long pos, long length) throws SQLException {
464 isValid();
465 if (pos < 1 || pos > this.length()) {
466 throw new SerialException("Invalid position in BLOB object set");
467 }
468 if (length < 1 || length > len - pos + 1) {
469 throw new SerialException("length is < 1 or pos + length >"
470 + "total number of bytes");
471 }
472 return new ByteArrayInputStream(buf, (int) pos - 1, (int) length);
473 }
474
475
476 /**
477 * This method frees the {@code SeriableBlob} object and releases the
478 * resources that it holds. The object is invalid once the {@code free}
479 * method is called. <p> If {@code free} is called multiple times, the
480 * subsequent calls to {@code free} are treated as a no-op. </P>
481 *
482 * @throws SQLException if an error occurs releasing the Blob's resources
483 * @since 1.6
484 */
485 public void free() throws SQLException {
486 if (buf != null) {
487 buf = null;
488 if (blob != null) {
489 blob.free();
490 }
491 blob = null;
492 }
493 }
494
495 /**
496 * Compares this SerialBlob to the specified object. The result is {@code
497 * true} if and only if the argument is not {@code null} and is a {@code
498 * SerialBlob} object that represents the same sequence of bytes as this
499 * object.
500 *
501 * @param obj The object to compare this {@code SerialBlob} against
502 *
503 * @return {@code true} if the given object represents a {@code SerialBlob}
504 * equivalent to this SerialBlob, {@code false} otherwise
505 *
506 */
507 public boolean equals(Object obj) {
508 if (this == obj) {
509 return true;
510 }
511 if (obj instanceof SerialBlob) {
512 SerialBlob sb = (SerialBlob)obj;
513 if (this.len == sb.len) {
514 return Arrays.equals(buf, sb.buf);
515 }
516 }
517 return false;
518 }
519
520 /**
521 * Returns a hash code for this {@code SerialBlob}.
522 * @return a hash code value for this object.
523 */
524 public int hashCode() {
525 return ((31 + Arrays.hashCode(buf)) * 31 + (int)len) * 31 + (int)origLen;
526 }
527
528 /**
529 * Returns a clone of this {@code SerialBlob}. The copy will contain a
530 * reference to a clone of the internal byte array, not a reference
531 * to the original internal byte array of this {@code SerialBlob} object.
532 * The underlying {@code Blob} object will be set to null.
533 *
534 * @return a clone of this SerialBlob
535 */
536 public Object clone() {
537 try {
538 SerialBlob sb = (SerialBlob) super.clone();
539 sb.buf = (buf != null) ? Arrays.copyOf(buf, (int)len) : null;
540 sb.blob = null;
541 return sb;
542 } catch (CloneNotSupportedException ex) {
543 // this shouldn't happen, since we are Cloneable
544 throw new InternalError();
545 }
546
547 }
548
549 /**
550 * readObject is called to restore the state of the SerialBlob from
551 * a stream.
552 */
553 private void readObject(ObjectInputStream s)
554 throws IOException, ClassNotFoundException {
555
556 ObjectInputStream.GetField fields = s.readFields();
557 byte[] tmp = (byte[])fields.get("buf", null);
558 if (tmp == null)
559 throw new InvalidObjectException("buf is null and should not be!");
560 buf = tmp.clone();
561 len = fields.get("len", 0L);
562 if (buf.length != len)
563 throw new InvalidObjectException("buf is not the expected size");
564 origLen = fields.get("origLen", 0L);
565 blob = (Blob) fields.get("blob", null);
566 }
567
568 /**
569 * writeObject is called to save the state of the SerialBlob
570 * to a stream.
571 */
572 private void writeObject(ObjectOutputStream s)
573 throws IOException, ClassNotFoundException {
574
575 ObjectOutputStream.PutField fields = s.putFields();
576 fields.put("buf", buf);
577 fields.put("len", len);
578 fields.put("origLen", origLen);
579 // Note: this check to see if it is an instance of Serializable
580 // is for backwards compatibiity
581 fields.put("blob", blob instanceof Serializable ? blob : null);
582 s.writeFields();
583 }
584
585 /**
586 * Check to see if this object had previously had its {@code free} method
587 * called
588 *
589 * @throws SerialException
590 */
591 private void isValid() throws SerialException {
592 if (buf == null) {
593 throw new SerialException("Error: You cannot call a method on a "
594 + "SerialBlob instance once free() has been called.");
595 }
596 }
597
598 /**
599 * The identifier that assists in the serialization of this
600 * {@code SerialBlob} object.
601 */
602 static final long serialVersionUID = -8144641928112860441L;
603 }