JBoss : How to unwrap Connections got from DataSource

    /**
     * Reads a file into a BLOB.
     * 
     * @return BLOB
     * @throws IOException
     * @throws SQLException
     */
    private BLOB getBlobData(Connection conn, InputStream is) throws IOException, SQLException {
        BLOB fileData = null;

        if (is == null) {
            final String msg = "Unable to read from InputStream because it is null";
            mLogger.error(msg);
            throw new IOException(msg);
        }
        else {
            ByteArrayOutputStream blobStream = new ByteArrayOutputStream();
            GZIPOutputStream gzipOutStrm = new GZIPOutputStream(blobStream);
            byte[] buffer = new byte[512];
            int length = 0;
            while ((length = is.read(buffer)) != -1) {
                gzipOutStrm.write(buffer, 0, length);
            }

            gzipOutStrm.close();

            /*
             * Although BLOB.createTemporary takes a java.sql.Connection object
             * as a parameter, it ONLY works if the Connection is an
             * oracle.jdbc.driver.OracleConnection object. If it's not an
             * oracle.jdbc.driver.OracleConnection, you get a
             * ClassCastException.
             * 
             * In JBoss, when we get the database connection via a DataSource
             * object looked up via JNDI, the connection is not a real
             * OracleConnection object, but an object that wraps the real
             * OracleConnection.
             * 
             * The JBossNativeJdbcExtractor is used to get the underlying
             * connection from the wrapped connection. Note that this does not
             * tie the code to JBoss - If the given Connection is not a JBoss
             * wrapper, it will be returned as-is.
             */

            JBossNativeJdbcExtractor nativeJdbcExtractor = new JBossNativeJdbcExtractor();

            Connection nativeConnection = nativeJdbcExtractor.getNativeConnection(conn);

            if (mLogger.isDebugEnabled()) {
                StringBuilder msg = new StringBuilder("Retrieved native connection : ");
                msg.append((nativeConnection != null) ? nativeConnection.getClass().getName() : "null");
                msg.append(" from wrapped connection : ");
                msg.append((conn != null) ? conn.getClass().getName() : "null");
                mLogger.debug(msg.toString());
            }

            fileData = BLOB.createTemporary(nativeConnection, false,
                    oracle.sql.BLOB.DURATION_SESSION);
            fileData.setBytes(1, blobStream.toByteArray());
            blobStream.close();
        }
        return fileData;
    }