Oracle BLOB Writes the Bytes Twice to Output Stream

Question

Hi,
I have a very strange problem when working with oracle.sql.BLOB; I cannot figure out what it's causing my BLOB stream output to double the amount of data inserted into the Oracle database. I have a table that contains two BLOB objects(image files) and the goal is to insert two images into each row by BLOB stream.
For example, if the image_bin size is 800k and image_thumbnail size is 100k, this code actually writes 1600k (double) and 200k (double) the amount of bytes to each BLOB column, respectively. The print method in insertBlob() indicates a correct number of bytes being written to the output stream (800k and 100k).
I know for the fact the retrieval method (not mentioned here) doesn't duplicate the bytes when it's read because I have written another test program that does not utilize oracle.sql.BLOB but instead uses PreparedStatement's setBinaryStream(index, InputStream, size_of_file) and it accurately writes the exact image size (no double sizing) to the database -- but not with BLOB. Here's a snippet of my code, note that the actual writing occurs in insertBlob():
private void insertBlob(java.sql.Blob lobImage, String imgName)
throws SQLException, IOException {
File imgFile = null;
FileInputStream imgOnDisk = null;
OutputStream imgToDB = null;
int bufferSize = 0;
oracle.sql.BLOB blobImage = (oracle.sql.BLOB) lobImage;
try {
int bytesRead = 0;
long bytesWritten = 0L;
byte[] byteBuffer = null;
bufferSize = blobImage.getBufferSize();
byteBuffer = new byte[bufferSize];
imgFile = new File(imgName);
// Stream to read the file from the local disk
imgOnDisk = new FileInputStream(imgFile);
// Stream to write to the Oracle database
imgToDB = blobImage.setBinaryStream(imgFile.length());
// Read from the disk file and write to the database
while ((bytesRead = imgOnDisk.read(byteBuffer)) != -1 ) {
imgToDB.write(byteBuffer, 0, bytesRead);
bytesWritten += bytesRead;
} // end of while
System.out.print("Done. " + bytesWritten + "-bytes inserted, buffer size: " +
bufferSize + "-bytes, chunk size: " +
blobImage.getChunkSize() + ".\n");
} catch (SQLException sqlEx) {
System.out.println("SQLException caught: JDBCOracleLOBBinaryStream.processBlob()");
connRollback();
throw sqlEx;
} catch (IOException ioe) {
System.out.println("IOException caught: JDBCOracleLOBBinaryStream.processBlob()");
throw ioe;
} finally {
try {
if (imgOnDisk != null ) {
imgOnDisk.close();
if (imgToDB != null ) {
imgToDB.close();
} catch (IOException ioeClosing) {
System.out.println("IOException caught: JDBCOracleLOBBinaryStream.processBlob() " +
"on closing stream.");
ioeClosing.printStackTrace();
} // end of finally
public void insertImageIntoOracleDB() throws SQLException, IOException {
PreparedStatement pstmt = null;
Statement stmt = null;
ResultSet rset = null;
try {
this.getConnection(_driver, host, port, database, user, _pass);
pstmt = conn.prepareStatement("INSERT INTO " +
" gallery_v (picture_id, picture_title, image_bin, image_thumbnail) " +
" VALUES (?, ?, EMPTY_BLOB(), EMPTY_BLOB())");
pstmt.setInt(1, picID);
pstmt.setString(2, picTitle);
pstmt.executeUpdate();
stmt = conn.createStatement();
rset = stmt.executeQuery("SELECT image_bin, image_thumbnail FROM gallery_v " +
" WHERE picture_id = " + picID + " FOR UPDATE");
int rsetCount = 0;
oracle.sql.BLOB imgBlob = null;
oracle.sql.BLOB imgThumbBlob = null;
while (rset.next()) {
imgBlob = ((OracleResultSet) rset).getBLOB("image_bin");
System.out.print("Inserting " + img + "... ");
insertBlob(imgBlob, img);
imgThumbBlob = ((OracleResultSet) rset).getBLOB("image_thumbnail");
System.out.print("Inserting " + imgThumb + "... ");
insertBlob(imgThumbBlob, imgThumb);
rsetCount++;
System.out.println("\nNumber of rows updated: " + rsetCount);
conn.commit();
} catch (SQLException sqlEx) {
System.out.println("SQLException caught: JDBCOracleLOBBinaryStream.insertImageIntoOracleDB()");
connRollback();
throw sqlEx;
} catch (IOException ioe) {
throw ioe;
} finally {
try {
if (rset != null) {
rset.close();
if (pstmt != null) {
pstmt.close();
if (stmt != null) {
stmt.close();
closeConnection();
} catch (SQLException closingSqlEx) {
System.out.println("SQLException caught: JDBCOracleLOBBinaryStream.insertImageIntoOracleDB() " +
"on closing ResultSet or PreparedStatement.");
closingSqlEx.printStackTrace();
} // end of finally
}

Answer 1

Make a lumpy mistake; the new BLOB#setBinaryStream() method takes a position of where the data is read from in the stream given to it. So the following code:
imgToDB = blobImage.setBinaryStream(imgFile.length());
Starts off from the end of the file. Now I don't understand how this position would result in the duplicated amount of bytes read from the binary file (an image here) to the output stream! The correct line should be:
imgToDB = blobImage.setBinaryStream(0L);
ARGH!!! Now everything works as it expected. I gotta read the API's more carefully as I was expecting the same semantic parameter as PreparedStatement#setBinaryStream() which takes the length of the stream as one of its parameters.