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* Trouble with large objets and jdbc
@ 1999-05-12 11:35 Henri-Pierre CHARLES <hpc@prism.uvsq.fr>
1999-05-13 15:26 ` Re: [INTERFACES] Trouble with large objets and jdbc Brian P Millett <bpm@ec-group.com>
0 siblings, 1 reply; 2+ messages in thread
From: Henri-Pierre CHARLES @ 1999-05-12 11:35 UTC (permalink / raw)
To: pgsql-interfaces@hub.org
Hello,
I want to use large objets to store images in a database with the jdbc
interface. I have try to use PreparedStatement which has
setBinaryStream () but it's not possible with the old version I
usually use (6.4.2). I have download the 6.5b1 and unfortunately
setBinaryStream () is still not implemented.
I have tried to store the uuencoded image in a text field but they are
a strict limitation of 8190 byte for a field, which is too small.
I have tried to use LargeObjects, with no luck. The example.blobtest
fail. I have join the error message at the end of this mail (I use
postgresql 6.5b1 on a FreeBSD 3.0 computer)
example.ImageViewer sometime fail
Somebody can help ?
Thanks
--
% Henri-Pierre.Charles@prism.uvsq.fr PRiSM, Université de Versailles
% Tel: 01 39 25 43 44 45, Av. des États Unis 78000 Versailles
% Il reste 58982399 secondes jusqu'au 01/01/2000
>java -Djdbc.driver=postgresql.Driver example.blobtest jdbc:postgresql:test anonymous ""
PostgreSQL blobtest v6.3 rev 1
Connecting to Database URL = jdbc:postgresql:test
Connected...Now creating a statement
----------------------------------------------------------------------
Testing postgresql large object api
Gaining access to large object api
Test 1 Creating a large object
Creating a large object
Opening test source object
Copying file to large object
Block size=2048 offset=0
Block size=2048 offset=2048
Block size=2048 offset=4096
Block size=413 offset=6144
Closing object
Test 2 Reading a large object and save as a file
Opening large object 18785
Opening test destination object
Copying large object to file
Exception caught.
java.sql.SQLException: IOError while reading from backend: java.io.IOException: The backend has broken the connection. Possibly the action you have attempted has caused it to close.
java.sql.SQLException: IOError while reading from backend: java.io.IOException: The backend has broken the connection. Possibly the action you have attempted has caused it to close.
at postgresql.PG_Stream.ReceiveChar(PG_Stream.java:183)
at postgresql.fastpath.Fastpath.fastpath(Fastpath.java:114)
at postgresql.fastpath.Fastpath.fastpath(Fastpath.java:188)
at postgresql.largeobject.LargeObject.seek(LargeObject.java:207)
at postgresql.largeobject.LargeObject.size(LargeObject.java:250)
at example.blobtest.ownapi_test2(blobtest.java:144)
at example.blobtest.ownapi(blobtest.java:77)
at example.blobtest.<init>(blobtest.java:50)
at example.blobtest.main(blobtest.java:188
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: [INTERFACES] Trouble with large objets and jdbc
1999-05-12 11:35 Trouble with large objets and jdbc Henri-Pierre CHARLES <hpc@prism.uvsq.fr>
@ 1999-05-13 15:26 ` Brian P Millett <bpm@ec-group.com>
0 siblings, 0 replies; 2+ messages in thread
From: Brian P Millett @ 1999-05-13 15:26 UTC (permalink / raw)
To: Henri-Pierre CHARLES <hpc@prism.uvsq.fr>; +Cc: pgsql-interfaces@hub.org
Henri-Pierre CHARLES wrote:
> Hello,
>
> I want to use large objets to store images in a database with the jdbc
> interface. I have try to use PreparedStatement which has
> setBinaryStream () but it's not possible with the old version I
> usually use (6.4.2). I have download the 6.5b1 and unfortunately
> setBinaryStream () is still not implemented.
This bug has been fixed as of Monday. They (Hackers group) have also fixed a big hairy bug with the backend. If you use the anonymous cvs to checkout the latest snapshot, you will
find an ImageViewer.java example that works, the blobtest.java works also.
I also use code such as this to work fine:
// The UPDATE statement to be used for populating the item_picture and
// item_descr columns
String itemUpdateStmt = "UPDATE item SET item_picture = ?, item_descr = ?"+
" WHERE item_num = ?";
// Create a PreparedStatement object & use it to update the item_picture
// and item_descr columns in the item table
PreparedStatement updateStmt = conn.prepareStatement(itemUpdateStmt);
// File names for the image & text files
String itemPictureFileName = ("item_" + new Integer(i).toString()
+ ".gif");
String itemDescrFileName = ("item_" + new Integer(i).toString()
+ ".txt");
// java.io.File objects corresponding to the image & text files
File itemPictureFile = new File(itemPictureFileName);
File itemDescrFile = new File(itemDescrFileName);
// Byte arrays to store text & byte data for the item_picture and
// item_descr columns
byte itemPictureArray [] = new byte[(int)itemPictureFile.length()];
String itemDescrString = "";
// Using java.io.FileInputStream to reading the image & text files
// into byte arrays
FileInputStream itemPictureInputStream = new
FileInputStream(itemPictureFile);
itemPictureInputStream.read(itemPictureArray, 0,
(int)itemPictureFile.length());
FileReader fr = new FileReader(itemDescrFile);
BufferedReader br = new BufferedReader(fr);
String lineIn;
while ((lineIn = br.readLine()) != null)
itemDescrString += lineIn;
// Set the values of the parameters & execute the statement
updateStmt.setBytes(1, itemPictureArray);
updateStmt.setString(2, itemDescrString);
updateStmt.setInt(3, i);
updateStmt.executeUpdate();
Then to read/view the image, I do:
// read the image from the resultset
byte itemPictureArray [] = queryResults.getBytes(2);
Image img = Toolkit.getDefaultToolkit().createImage(itemPictureArray);
itemPictureCanvas.setImage(img);
itemPictureCanvas.repaint();
--
Brian Millett
Enterprise Consulting Group "Heaven can not exist,
(314) 205-9030 If the family is not eternal"
bpm@ec-group.com F. Ballard Washburn
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1999-05-13 15:26 ` Brian P Millett <bpm@ec-group.com>
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