InputStream is = null;
OutputStream os = null;
Connection conn = null;
Blob value = null;

PreparedStatement stmt =
conn.prepareStatement("SELECT attachment FROM user.table WHERE id = 1");
stmt.setBigDecimal(1, idValue);
ResultSet rs2 = stmt.executeQuery();
while(rs2.next()) {
    value = rs2.getBlob("attachment");
}

is = data.getInputStream();
os = value.setBinaryStream(0L);
byte[] buffer = new byte[2048];
int i;
while((i = is.read(buffer)) > -1) {
    os.write(buffer, 0, i);
}