Re: create BLOB question

So does setBytes() insert or overwrite the data starting at a position?

On Mon, 2003-02-10 at 15:28, David Wall wrote:
> > does some9one out there know how to create a new oid from scratch.
> > setBytes on 7.2 worked fine for me, but with the change to 7.3 I can't
> > seem to get a new oid number. I want to avoid any postgres specific
> > stuff. Correct me if I'm wrong, but It seems to me that the setBytes
> > goes with the bytea stuff and the BLOB stuff goes with the oid stuff. I
> > just can't seem to figure out how to insert a new oid/BLOB.
> >
> > any help would be great,
>
> You will need to use the setBlob() call on prepared statement. The trick is
> that you'll need a wrapper that can take your byte array and pretend it's a
> java.sql.Blob interface so that the driver can use it. In my code, Oracle
> does it different, with an empty_blob() being first created, and then
> updated with the blob data (why, I'll never know!).
>
> Below is a utility class that we use so that our mainline call, which has a
> byte array, can just do the following:
> YoByteBlob myBlob = new YoByteBlob( myByteArray );
> if ( ! isOracle )
> stmt.setBlob(1,myBlob);
>
>
> // Copyright (c) 2002 Yozons, Inc. All rights reserved.
> // This file is proprietary.
> //
> package com.yozons.jdbc;
>
> import java.sql.SQLException;
>
> /**
> * Screwy wrapper class so that we can insert a Blob into the database from
> a byte array.
> * Includes more screwy stuff for Oracle specific updating of a blob (the
> only way to insert a new blob).
> *
> * @author David Wall
> */
> public class YoByteBlob
> implements java.sql.Blob
> {
> byte[] bytes = null;
>
> /**
> * Creates a YoByteBlob using the specified byte array.
> */
> public YoByteBlob(byte[] b)
> {
> bytes = b;
> }
>
> // My own constructor for taking a Blob of input and returning as an
> array
> public YoByteBlob(java.sql.Blob b)
> {
> java.io.InputStream is = null;
> try
> {
> is = b.getBinaryStream();
> bytes = new byte[(int)b.length()];
> is.read(bytes);
> }
> catch( java.sql.SQLException e )
> {
> bytes = null;
> }
> catch( java.io.IOException e )
> {
> bytes = null;
> }
> finally
> {
> try
> {
> if ( is != null )
> is.close();
> }
> catch( Exception e ) {}
> }
> }
>
> public long length()
> throws java.sql.SQLException
> {
> return bytes.length;
> }
>
> // My own API call for simplicity
> public byte[] getBytes()
> {
> return bytes;
> }
>
> public byte[] getBytes(long pos, int length)
> throws java.sql.SQLException
> {
> if ( pos == 0 && length == bytes.length )
> return bytes;
>
> try
> {
> byte[] newbytes = new byte[length];
> System.arraycopy(bytes, (int)pos, newbytes, 0, length);
> return newbytes;
> }
> catch( Exception e )
> {
> throw new java.sql.SQLException("Could not get subset of
> array");
> }
> }
>
> public java.io.InputStream getBinaryStream()
> throws java.sql.SQLException
> {
> return new java.io.ByteArrayInputStream(bytes);
> }
>
> public long position(byte[] pattern, long start)
> throws java.sql.SQLException
> {
> throw new java.sql.SQLException("Unsupported position() for blob");
> }
>
> public long position(java.sql.Blob pattern, long start)
> throws java.sql.SQLException
> {
> throw new java.sql.SQLException("Unsupported position() for blob");
> }
>
>
> /**
> * Routine used to put the "real" object into an Oracle database, which
> requires
> * creating an empty blob, then retrieving it again and updating it from
> there.
> */
> public void updateOracleBlob(java.sql.Blob b)
> throws java.sql.SQLException
> {
> java.io.OutputStream outstream = null;
>
> try
> {
> if ( b == null )
> throw new SQLException("YoByteBlob.updateOracleBlob() blob
> was null");
> if ( ! (b instanceof oracle.sql.BLOB) )
> throw new SQLException("YoByteBlob.updateOracleBlob() blob
> not an oracle.sql.BLOB object; is: " +
> b.getClass().getName() );
> if ( bytes == null )
> throw new SQLException("YoByteBlob.updateOracleBlob() no
> blob bytes to write");
>
> oracle.sql.BLOB blob = (oracle.sql.BLOB)b;
> outstream = blob.getBinaryOutputStream();
>
> int bufSize = blob.getBufferSize();
> int pos = 0;
> int remaining = bytes.length;
> while ( remaining > 0 )
> {
> int numOut = Math.min(bufSize,remaining);
> outstream.write(bytes, pos, numOut);
> pos += numOut;
> remaining -= numOut;
> }
> }
> catch( java.io.IOException e )
> {
> throw new java.sql.SQLException("YoByteBlob.updateOracleBlob()
> I/O failure: " + e.getMessage());
> }
> finally
> {
> try
> {
> if ( outstream != null )
> outstream.close();
> }
> catch( java.io.IOException e )
> {
> throw new
> java.sql.SQLException("YoByteBlob.updateOracleBlob() close I/O failure: " +
> e.getMessage());
> }
> }
> }
> }
>
>
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--
Jeremiah Jahn <jeremiah(at)cs(dot)earlham(dot)edu>