BLOB Manipulation

From: Aviran Levy <avlevy2k_at_hotmail.com>
Date: Thu, 25 Oct 2001 15:56:06 -0400
Message-ID: <Z7_B7.306$0N4.36721_at_news.shore.net>

Thanks for the help,
[Quoted] First I would like to ask if the book "Oracle8i JDBC Developer's Guide and Reference" is available online.

[Quoted] As for the solution you described in your message, When I try to run it I get an exception thrown from the oracle server saying that the "row containing the lob object is not locked". I know that if I run a stored procedure to manipulate a BLOB object I can lock the row by adding the 'for [Quoted] update' to the select query and the 'commit' after making the modification. [Quoted] That's obviously not the case here. any ideas how to lock a row in java code?

[Quoted] Furthermore, do you happen to know a place when I can get the documentation [Quoted] for the oracle BLOB object since I also need to access the data in the BLOB. [Quoted] in the example you gave in your message I would like also to do the opposite - how is it possible to get data from the BLOB object and store it in a new file ?

Thanks a lot
-- Avi

[Quoted] "Sergey M" <msu_at_pronto.msk.ru> wrote in message news:9r8lnt$116k$1_at_serv2.vsi.ru...
> "Aviran Levy" <avlevy2k_at_hotmail.com> ÓÏÏÂÝÉÌ/ÓÏÏÂÝÉÌÁ × ÎÏ×ÏÓÔÑÈ
ÓÌÅÄÕÀÝÅÅ:
> news:ZfAB7.133$0N4.17635_at_news.shore.net...
> > Hi,
> > From a java application I'm trying to do:
> > ...
> > Blob b = rs.getBlob("ZIP_FILE");
> > b.setBytes(1,byteArray);
> > ...
> > but apparently I get a runtime exception since my oracle jdbc driver
> doesn't
> > have implementation for the setBytes method. I probably need a newer
> oracle
> > jdbc driver. Is anyone know where can I find one?
> > Is anyone having that problem too?
> > My goal is to store a zip file on the Oracle server and manipulate it
from
> > the java application (avoiding calls for store procedures). If anyone
> knows
> > a better way to do that then please... I'll appreciate any help about
it.
> > Note: to use setBytes you have to use JDK1.4
> > Thanks,
> > -- Avi
>
> 1. Begin by using SQL statements to create the BLOB entry in the table.
> Use the empty_blob syntax to create the BLOB locator.
>
> stmt.execute ("INSERT INTO my_blob_table VALUES ('row1',
> empty_blob())");
>
> 2. Get the BLOB locator from the table.
>
> BLOB blob;
> cmd = "SELECT * FROM my_blob_table WHERE X='row1'";
> ResultSet rest = stmt.executeQuery(cmd);
> BLOB blob = ((OracleResultSet)rset).getBLOB(2);
>
> 3. Declare a file handler for the john.gif file, then print the length of
> the file. This value will be used later
> to ensure that the entire file is read into the BLOB. Next, create a
> FileInputStream object to read the
> contents of the GIF file, and an OutputStream object to retrieve the
> BLOB as a stream.
>
> File binaryFile = new File("YOUR_ZIP_FILE");
> System.out.println("john.gif length = " + binaryFile.length());
> FileInputStream instream = new FileInputStream(binaryFile);
> OutputStream outstream = blob.getBinaryOutputStream();
>
>
> 4. Call getBufferSize() to retrieve the ideal buffer size (according to
> calculations by the JDBC driver) to use in
> writing to the BLOB, then create the buffer byte array.
>
> int size = blob.getBufferSize();
> byte[] buffer = new byte[size];
> int length = -1;
>
> 5. Use the read() method to read the GIF file to the byte array buffer,
then
> use the write() method to write it to
> the BLOB. When you finish, close the input and output streams.
>
> while ((length = instream.read(buffer)) != -1)
> outstream.write(buffer, 0, length);
> instream.close();
> outstream.close();
>
> This fragment is from "Oracle8i JDBC Developer's Guide and Reference"
> charpter 7 "Working with LOBs and BFILEs"
>
> Sergey M.
>
> P.S. Knowledge is of two kinds. We know a subject ourselves, or we know
> where we can find information upon it. --Samuel Johnson
>
>
Received on Thu Oct 25 2001 - 21:56:06 CEST