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25 
26 package javax.sql.rowset.serial;
27 
28 import java.sql.*;
29 import java.io.*;
30 import java.util.Arrays;
31 
32 /**
33  * A serialized mapping in the Java programming language of an SQL
34  * <code>CLOB</code> value.
35  * <P>
36  * The <code>SerialClob</code> class provides a constructor for creating
37  * an instance from a <code>Clob</code> object.  Note that the <code>Clob</code>
38  * object should have brought the SQL <code>CLOB</code> value's data over
39  * to the client before a <code>SerialClob</code> object
40  * is constructed from it.  The data of an SQL <code>CLOB</code> value can
41  * be materialized on the client as a stream of Unicode characters.
42  * <P>
43  * <code>SerialClob</code> methods make it possible to get a substring
44  * from a <code>SerialClob</code> object or to locate the start of
45  * a pattern of characters.
46  *
47  * <h3> Thread safety </h3>
48  *
49  * <p> A SerialClob is not safe for use by multiple concurrent threads.  If a
50  * SerialClob is to be used by more than one thread then access to the SerialClob
51  * should be controlled by appropriate synchronization.
52  *
53  * @author Jonathan Bruce
54  * @since 1.5
55  */
56 public class SerialClob implements Clob, Serializable, Cloneable {
57 
58     /**
59      * A serialized array of characters containing the data of the SQL
60      * <code>CLOB</code> value that this <code>SerialClob</code> object
61      * represents.
62      *
63      * @serial
64      */
65     private char buf[];
66 
67     /**
68      * Internal Clob representation if SerialClob is initialized with a
69      * Clob. Null if SerialClob is initialized with a char[].
70      */
71     private Clob clob;
72 
73     /**
74      * The length in characters of this <code>SerialClob</code> object's
75      * internal array of characters.
76      *
77      * @serial
78      */
79     private long len;
80 
81     /**
82      * The original length in characters of this <code>SerialClob</code>
83      * object's internal array of characters.
84      *
85      * @serial
86      */
87     private long origLen;
88 
89     /**
90      * Constructs a <code>SerialClob</code> object that is a serialized version of
91      * the given <code>char</code> array.
92      * <p>
93      * The new <code>SerialClob</code> object is initialized with the data from the
94      * <code>char</code> array, thus allowing disconnected <code>RowSet</code>
95      * objects to establish a serialized <code>Clob</code> object without touching
96      * the data source.
97      *
98      * @param ch the char array representing the <code>Clob</code> object to be
99      *         serialized
100      * @throws SerialException if an error occurs during serialization
101      * @throws SQLException if a SQL error occurs
102      */
SerialClob(char ch[])103     public SerialClob(char ch[]) throws SerialException, SQLException {
104 
105         // %%% JMB. Agreed. Add code here to throw a SQLException if no
106         // support is available for locatorsUpdateCopy=false
107         // Serializing locators is not supported.
108 
109         len = ch.length;
110         buf = new char[(int)len];
111         for (int i = 0; i < len ; i++){
112            buf[i] = ch[i];
113         }
114         origLen = len;
115         clob = null;
116     }
117 
118     /**
119      * Constructs a <code>SerialClob</code> object that is a serialized
120      * version of the given <code>Clob</code> object.
121      * <P>
122      * The new <code>SerialClob</code> object is initialized with the
123      * data from the <code>Clob</code> object; therefore, the
124      * <code>Clob</code> object should have previously brought the
125      * SQL <code>CLOB</code> value's data over to the client from
126      * the database. Otherwise, the new <code>SerialClob</code> object
127      * object will contain no data.
128      * <p>
129      * Note: The <code>Clob</code> object supplied to this constructor must
130      * return non-null for both the <code>Clob.getCharacterStream()</code>
131      * and <code>Clob.getAsciiStream</code> methods. This <code>SerialClob</code>
132      * constructor cannot serialize a <code>Clob</code> object in this instance
133      * and will throw an <code>SQLException</code> object.
134      *
135      * @param  clob the <code>Clob</code> object from which this
136      *     <code>SerialClob</code> object is to be constructed; cannot be null
137      * @throws SerialException if an error occurs during serialization
138      * @throws SQLException if a SQL error occurs in capturing the CLOB;
139      *     if the <code>Clob</code> object is a null; or if either of the
140      *     <code>Clob.getCharacterStream()</code> and <code>Clob.getAsciiStream()</code>
141      *     methods on the <code>Clob</code> returns a null
142      * @see java.sql.Clob
143      */
SerialClob(Clob clob)144     public SerialClob(Clob clob) throws SerialException, SQLException {
145 
146         if (clob == null) {
147             throw new SQLException("Cannot instantiate a SerialClob " +
148                 "object with a null Clob object");
149         }
150         len = clob.length();
151         this.clob = clob;
152         buf = new char[(int)len];
153         int read = 0;
154         int offset = 0;
155 
156         try (Reader charStream = clob.getCharacterStream()) {
157             if (charStream == null) {
158                 throw new SQLException("Invalid Clob object. The call to getCharacterStream " +
159                     "returned null which cannot be serialized.");
160             }
161 
162             // Note: get an ASCII stream in order to null-check it,
163             // even though we don't do anything with it.
164             try (InputStream asciiStream = clob.getAsciiStream()) {
165                 if (asciiStream == null) {
166                     throw new SQLException("Invalid Clob object. The call to getAsciiStream " +
167                         "returned null which cannot be serialized.");
168                 }
169             }
170 
171             try (Reader reader = new BufferedReader(charStream)) {
172                 do {
173                     read = reader.read(buf, offset, (int)(len - offset));
174                     offset += read;
175                 } while (read > 0);
176             }
177         } catch (java.io.IOException ex) {
178             throw new SerialException("SerialClob: " + ex.getMessage());
179         }
180 
181         origLen = len;
182     }
183 
184     /**
185      * Retrieves the number of characters in this <code>SerialClob</code>
186      * object's array of characters.
187      *
188      * @return a <code>long</code> indicating the length in characters of this
189      *         <code>SerialClob</code> object's array of character
190      * @throws SerialException if an error occurs;
191      * if {@code free} had previously been called on this object
192      */
length()193     public long length() throws SerialException {
194         isValid();
195         return len;
196     }
197 
198     /**
199      * Returns this <code>SerialClob</code> object's data as a stream
200      * of Unicode characters. Unlike the related method, <code>getAsciiStream</code>,
201      * a stream is produced regardless of whether the <code>SerialClob</code> object
202      * was created with a <code>Clob</code> object or a <code>char</code> array.
203      *
204      * @return a <code>java.io.Reader</code> object containing this
205      *         <code>SerialClob</code> object's data
206      * @throws SerialException if an error occurs;
207      * if {@code free} had previously been called on this object
208      */
getCharacterStream()209     public java.io.Reader getCharacterStream() throws SerialException {
210         isValid();
211         return (java.io.Reader) new CharArrayReader(buf);
212     }
213 
214     /**
215      * Retrieves the <code>CLOB</code> value designated by this <code>SerialClob</code>
216      * object as an ascii stream. This method forwards the <code>getAsciiStream</code>
217      * call to the underlying <code>Clob</code> object in the event that this
218      * <code>SerialClob</code> object is instantiated with a <code>Clob</code>
219      * object. If this <code>SerialClob</code> object is instantiated with
220      * a <code>char</code> array, a <code>SerialException</code> object is thrown.
221      *
222      * @return a <code>java.io.InputStream</code> object containing
223      *     this <code>SerialClob</code> object's data
224      * @throws SerialException if this {@code SerialClob} object was not
225      * instantiated with a <code>Clob</code> object;
226      * if {@code free} had previously been called on this object
227      * @throws SQLException if there is an error accessing the
228      *     <code>CLOB</code> value represented by the <code>Clob</code> object
229      * that was used to create this <code>SerialClob</code> object
230      */
getAsciiStream()231     public java.io.InputStream getAsciiStream() throws SerialException, SQLException {
232         isValid();
233         if (this.clob != null) {
234             return this.clob.getAsciiStream();
235         } else {
236             throw new SerialException("Unsupported operation. SerialClob cannot " +
237                 "return a the CLOB value as an ascii stream, unless instantiated " +
238                 "with a fully implemented Clob object.");
239         }
240     }
241 
242     /**
243      * Returns a copy of the substring contained in this
244      * <code>SerialClob</code> object, starting at the given position
245      * and continuing for the specified number or characters.
246      *
247      * @param pos the position of the first character in the substring
248      *            to be copied; the first character of the
249      *            <code>SerialClob</code> object is at position
250      *            <code>1</code>; must not be less than <code>1</code>,
251      *            and the sum of the starting position and the length
252      *            of the substring must be less than the length of this
253      *            <code>SerialClob</code> object
254      * @param length the number of characters in the substring to be
255      *               returned; must not be greater than the length of
256      *               this <code>SerialClob</code> object, and the
257      *               sum of the starting position and the length
258      *               of the substring must be less than the length of this
259      *               <code>SerialClob</code> object
260      * @return a <code>String</code> object containing a substring of
261      *         this <code>SerialClob</code> object beginning at the
262      *         given position and containing the specified number of
263      *         consecutive characters
264      * @throws SerialException if either of the arguments is out of bounds;
265      * if {@code free} had previously been called on this object
266      */
getSubString(long pos, int length)267     public String getSubString(long pos, int length) throws SerialException {
268 
269         isValid();
270         if (pos < 1 || pos > this.length()) {
271             throw new SerialException("Invalid position in SerialClob object set");
272         }
273 
274         if ((pos-1) + length > this.length()) {
275             throw new SerialException("Invalid position and substring length");
276         }
277 
278         try {
279             return new String(buf, (int)pos - 1, length);
280 
281         } catch (StringIndexOutOfBoundsException e) {
282             throw new SerialException("StringIndexOutOfBoundsException: " +
283                 e.getMessage());
284         }
285 
286     }
287 
288     /**
289      * Returns the position in this <code>SerialClob</code> object
290      * where the given <code>String</code> object begins, starting
291      * the search at the specified position. This method returns
292      * <code>-1</code> if the pattern is not found.
293      *
294      * @param searchStr the <code>String</code> object for which to
295      *                  search
296      * @param start the position in this <code>SerialClob</code> object
297      *         at which to start the search; the first position is
298      *         <code>1</code>; must not be less than <code>1</code> nor
299      *         greater than the length of this <code>SerialClob</code> object
300      * @return the position at which the given <code>String</code> object
301      *         begins, starting the search at the specified position;
302      *         <code>-1</code> if the given <code>String</code> object is
303      *         not found or the starting position is out of bounds; position
304      *         numbering for the return value starts at <code>1</code>
305      * @throws SerialException  if the {@code free} method had been
306      * previously called on this object
307      * @throws SQLException if there is an error accessing the Clob value
308      *         from the database.
309      */
position(String searchStr, long start)310     public long position(String searchStr, long start)
311         throws SerialException, SQLException {
312         isValid();
313         if (start < 1 || start > len) {
314             return -1;
315         }
316 
317         char pattern[] = searchStr.toCharArray();
318 
319         int pos = (int)start-1;
320         int i = 0;
321         long patlen = pattern.length;
322 
323         while (pos < len) {
324             if (pattern[i] == buf[pos]) {
325                 if (i + 1 == patlen) {
326                     return (pos + 1) - (patlen - 1);
327                 }
328                 i++; pos++; // increment pos, and i
329 
330             } else if (pattern[i] != buf[pos]) {
331                 pos++; // increment pos only
332             }
333         }
334         return -1; // not found
335     }
336 
337     /**
338      * Returns the position in this <code>SerialClob</code> object
339      * where the given <code>Clob</code> signature begins, starting
340      * the search at the specified position. This method returns
341      * <code>-1</code> if the pattern is not found.
342      *
343      * @param searchStr the <code>Clob</code> object for which to search
344      * @param start the position in this <code>SerialClob</code> object
345      *        at which to begin the search; the first position is
346      *         <code>1</code>; must not be less than <code>1</code> nor
347      *         greater than the length of this <code>SerialClob</code> object
348      * @return the position at which the given <code>Clob</code>
349      *         object begins in this <code>SerialClob</code> object,
350      *         at or after the specified starting position
351      * @throws SerialException if an error occurs locating the Clob signature;
352      * if the {@code free} method had been previously called on this object
353      * @throws SQLException if there is an error accessing the Clob value
354      *         from the database
355      */
position(Clob searchStr, long start)356     public long position(Clob searchStr, long start)
357         throws SerialException, SQLException {
358         isValid();
359         return position(searchStr.getSubString(1,(int)searchStr.length()), start);
360     }
361 
362     /**
363      * Writes the given Java <code>String</code> to the <code>CLOB</code>
364      * value that this <code>SerialClob</code> object represents, at the position
365      * <code>pos</code>.
366      *
367      * @param pos the position at which to start writing to the <code>CLOB</code>
368      *         value that this <code>SerialClob</code> object represents; the first
369      *         position is <code>1</code>; must not be less than <code>1</code> nor
370      *         greater than the length of this <code>SerialClob</code> object
371      * @param str the string to be written to the <code>CLOB</code>
372      *        value that this <code>SerialClob</code> object represents
373      * @return the number of characters written
374      * @throws SerialException if there is an error accessing the
375      *     <code>CLOB</code> value; if an invalid position is set; if an
376      *     invalid offset value is set; if number of bytes to be written
377      *     is greater than the <code>SerialClob</code> length; or the combined
378      *     values of the length and offset is greater than the Clob buffer;
379      * if the {@code free} method had been previously called on this object
380      */
setString(long pos, String str)381     public int setString(long pos, String str) throws SerialException {
382         return (setString(pos, str, 0, str.length()));
383     }
384 
385     /**
386      * Writes <code>len</code> characters of <code>str</code>, starting
387      * at character <code>offset</code>, to the <code>CLOB</code> value
388      * that this <code>Clob</code> represents.
389      *
390      * @param pos the position at which to start writing to the <code>CLOB</code>
391      *         value that this <code>SerialClob</code> object represents; the first
392      *         position is <code>1</code>; must not be less than <code>1</code> nor
393      *         greater than the length of this <code>SerialClob</code> object
394      * @param str the string to be written to the <code>CLOB</code>
395      *        value that this <code>Clob</code> object represents
396      * @param offset the offset into <code>str</code> to start reading
397      *        the characters to be written
398      * @param length the number of characters to be written
399      * @return the number of characters written
400      * @throws SerialException if there is an error accessing the
401      *     <code>CLOB</code> value; if an invalid position is set; if an
402      *     invalid offset value is set; if number of bytes to be written
403      *     is greater than the <code>SerialClob</code> length; or the combined
404      *     values of the length and offset is greater than the Clob buffer;
405      * if the {@code free} method had been previously called on this object
406      */
setString(long pos, String str, int offset, int length)407     public int setString(long pos, String str, int offset, int length)
408         throws SerialException {
409         isValid();
410         String temp = str.substring(offset);
411         char cPattern[] = temp.toCharArray();
412 
413         if (offset < 0 || offset > str.length()) {
414             throw new SerialException("Invalid offset in byte array set");
415         }
416 
417         if (pos < 1 || pos > this.length()) {
418             throw new SerialException("Invalid position in Clob object set");
419         }
420 
421         if ((long)(length) > origLen) {
422             throw new SerialException("Buffer is not sufficient to hold the value");
423         }
424 
425         if ((length + offset) > str.length()) {
426             // need check to ensure length + offset !> bytes.length
427             throw new SerialException("Invalid OffSet. Cannot have combined offset " +
428                 " and length that is greater that the Blob buffer");
429         }
430 
431         int i = 0;
432         pos--;  //values in the array are at position one less
433         while ( i < length || (offset + i +1) < (str.length() - offset ) ) {
434             this.buf[(int)pos + i ] = cPattern[offset + i ];
435             i++;
436         }
437         return i;
438     }
439 
440     /**
441      * Retrieves a stream to be used to write Ascii characters to the
442      * <code>CLOB</code> value that this <code>SerialClob</code> object represents,
443      * starting at position <code>pos</code>. This method forwards the
444      * <code>setAsciiStream()</code> call to the underlying <code>Clob</code> object in
445      * the event that this <code>SerialClob</code> object is instantiated with a
446      * <code>Clob</code> object. If this <code>SerialClob</code> object is instantiated
447      *  with a <code>char</code> array, a <code>SerialException</code> object is thrown.
448      *
449      * @param pos the position at which to start writing to the
450      *        <code>CLOB</code> object
451      * @return the stream to which ASCII encoded characters can be written
452      * @throws SerialException if SerialClob is not instantiated with a
453      *     Clob object;
454      * if the {@code free} method had been previously called on this object
455      * @throws SQLException if there is an error accessing the
456      *     <code>CLOB</code> value
457      * @see #getAsciiStream
458      */
setAsciiStream(long pos)459     public java.io.OutputStream setAsciiStream(long pos)
460         throws SerialException, SQLException {
461         isValid();
462          if (this.clob != null) {
463              return this.clob.setAsciiStream(pos);
464          } else {
465              throw new SerialException("Unsupported operation. SerialClob cannot " +
466                 "return a writable ascii stream\n unless instantiated with a Clob object " +
467                 "that has a setAsciiStream() implementation");
468          }
469     }
470 
471     /**
472      * Retrieves a stream to be used to write a stream of Unicode characters
473      * to the <code>CLOB</code> value that this <code>SerialClob</code> object
474      * represents, at position <code>pos</code>. This method forwards the
475      * <code>setCharacterStream()</code> call to the underlying <code>Clob</code>
476      * object in the event that this <code>SerialClob</code> object is instantiated with a
477      * <code>Clob</code> object. If this <code>SerialClob</code> object is instantiated with
478      * a <code>char</code> array, a <code>SerialException</code> is thrown.
479      *
480      * @param  pos the position at which to start writing to the
481      *        <code>CLOB</code> value
482      *
483      * @return a stream to which Unicode encoded characters can be written
484      * @throws SerialException if the SerialClob is not instantiated with
485      *     a Clob object;
486      * if the {@code free} method had been previously called on this object
487      * @throws SQLException if there is an error accessing the
488      *            <code>CLOB</code> value
489      * @see #getCharacterStream
490      */
setCharacterStream(long pos)491     public java.io.Writer setCharacterStream(long pos)
492         throws SerialException, SQLException {
493         isValid();
494         if (this.clob != null) {
495             return this.clob.setCharacterStream(pos);
496         } else {
497             throw new SerialException("Unsupported operation. SerialClob cannot " +
498                 "return a writable character stream\n unless instantiated with a Clob object " +
499                 "that has a setCharacterStream implementation");
500         }
501     }
502 
503     /**
504      * Truncates the <code>CLOB</code> value that this <code>SerialClob</code>
505      * object represents so that it has a length of <code>len</code>
506      * characters.
507      * <p>
508      * Truncating a <code>SerialClob</code> object to length 0 has the effect of
509      * clearing its contents.
510      *
511      * @param length the length, in bytes, to which the <code>CLOB</code>
512      *        value should be truncated
513      * @throws SerialException if there is an error accessing the
514      *        <code>CLOB</code> value;
515      * if the {@code free} method had been previously called on this object
516      */
truncate(long length)517     public void truncate(long length) throws SerialException {
518         isValid();
519         if (length > len) {
520            throw new SerialException
521               ("Length more than what can be truncated");
522         } else {
523              len = length;
524              // re-size the buffer
525 
526              if (len == 0) {
527                 buf = new char[] {};
528              } else {
529                 buf = (this.getSubString(1, (int)len)).toCharArray();
530              }
531         }
532     }
533 
534 
535     /**
536      * Returns a {@code Reader} object that contains a partial
537      * {@code SerialClob} value, starting
538      * with the character specified by pos, which is length characters in length.
539      *
540      * @param pos the offset to the first character of the partial value to
541      * be retrieved.  The first character in the {@code SerialClob} is at position 1.
542      * @param length the length in characters of the partial value to be retrieved.
543      * @return {@code Reader} through which the partial {@code SerialClob}
544      * value can be read.
545      * @throws SQLException if pos is less than 1 or if pos is greater than the
546      * number of characters in the {@code SerialClob} or if pos + length
547      * is greater than the number of characters in the {@code SerialClob};
548      * @throws SerialException if the {@code free} method had been previously
549      * called on this object
550      * @since 1.6
551      */
getCharacterStream(long pos, long length)552     public Reader getCharacterStream(long pos, long length) throws SQLException {
553         isValid();
554         if (pos < 1 || pos > len) {
555             throw new SerialException("Invalid position in Clob object set");
556         }
557 
558         if ((pos-1) + length > len) {
559             throw new SerialException("Invalid position and substring length");
560         }
561         if (length <= 0) {
562             throw new SerialException("Invalid length specified");
563         }
564         return new CharArrayReader(buf, (int)pos, (int)length);
565     }
566 
567     /**
568      * This method frees the {@code SerialClob} object and releases the
569      * resources that it holds.
570      * The object is invalid once the {@code free} method is called.
571      * <p>
572      * If {@code free} is called multiple times, the subsequent
573      * calls to {@code free} are treated as a no-op.
574      * </P>
575      * @throws SQLException if an error occurs releasing
576      * the Clob's resources
577      * @since 1.6
578      */
free()579     public void free() throws SQLException {
580         if (buf != null) {
581             buf = null;
582             if (clob != null) {
583                 clob.free();
584             }
585             clob = null;
586         }
587     }
588 
589     /**
590      * Compares this SerialClob to the specified object.  The result is {@code
591      * true} if and only if the argument is not {@code null} and is a {@code
592      * SerialClob} object that represents the same sequence of characters as this
593      * object.
594      *
595      * @param  obj The object to compare this {@code SerialClob} against
596      *
597      * @return  {@code true} if the given object represents a {@code SerialClob}
598      *          equivalent to this SerialClob, {@code false} otherwise
599      *
600      */
equals(Object obj)601     public boolean equals(Object obj) {
602         if (this == obj) {
603             return true;
604         }
605         if (obj instanceof SerialClob) {
606             SerialClob sc = (SerialClob)obj;
607             if (this.len == sc.len) {
608                 return Arrays.equals(buf, sc.buf);
609             }
610         }
611         return false;
612     }
613 
614     /**
615      * Returns a hash code for this {@code SerialClob}.
616      * @return  a hash code value for this object.
617      */
hashCode()618     public int hashCode() {
619        return ((31 + Arrays.hashCode(buf)) * 31 + (int)len) * 31 + (int)origLen;
620     }
621 
622     /**
623      * Returns a clone of this {@code SerialClob}. The copy will contain a
624      * reference to a clone of the internal character array, not a reference
625      * to the original internal character array of this {@code SerialClob} object.
626      * The underlying {@code Clob} object will be set to null.
627      *
628      * @return  a clone of this SerialClob
629      */
clone()630     public Object clone() {
631         try {
632             SerialClob sc = (SerialClob) super.clone();
633             sc.buf = (buf != null) ? Arrays.copyOf(buf, (int)len) : null;
634             sc.clob = null;
635             return sc;
636         } catch (CloneNotSupportedException ex) {
637             // this shouldn't happen, since we are Cloneable
638             throw new InternalError();
639         }
640     }
641 
642     /**
643      * readObject is called to restore the state of the SerialClob from
644      * a stream.
645      */
readObject(ObjectInputStream s)646     private void readObject(ObjectInputStream s)
647             throws IOException, ClassNotFoundException {
648 
649         ObjectInputStream.GetField fields = s.readFields();
650        char[] tmp = (char[])fields.get("buf", null);
651        if (tmp == null)
652            throw new InvalidObjectException("buf is null and should not be!");
653        buf = tmp.clone();
654        len = fields.get("len", 0L);
655        if (buf.length != len)
656            throw new InvalidObjectException("buf is not the expected size");
657        origLen = fields.get("origLen", 0L);
658        clob = (Clob) fields.get("clob", null);
659     }
660 
661     /**
662      * writeObject is called to save the state of the SerialClob
663      * to a stream.
664      */
writeObject(ObjectOutputStream s)665     private void writeObject(ObjectOutputStream s)
666             throws IOException, ClassNotFoundException {
667 
668         ObjectOutputStream.PutField fields = s.putFields();
669         fields.put("buf", buf);
670         fields.put("len", len);
671         fields.put("origLen", origLen);
672         // Note: this check to see if it is an instance of Serializable
673         // is for backwards compatibility
674         fields.put("clob", clob instanceof Serializable ? clob : null);
675         s.writeFields();
676     }
677 
678     /**
679      * Check to see if this object had previously had its {@code free} method
680      * called
681      *
682      * @throws SerialException
683      */
isValid()684     private void isValid() throws SerialException {
685         if (buf == null) {
686             throw new SerialException("Error: You cannot call a method on a "
687                     + "SerialClob instance once free() has been called.");
688         }
689     }
690 
691     /**
692      * The identifier that assists in the serialization of this {@code SerialClob}
693      * object.
694      */
695     static final long serialVersionUID = -1662519690087375313L;
696 }
697