Re: create BLOB question - Mailing list pgsql-jdbc

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@cs.earlham.edu>