Blob imageBlob = resultSet.getBlob(yourBlobColumnIndex);
InputStream binaryStream = imageBlob.getBinaryStream(0, imageBlob.length());
Alternatively, you can call:
byte imageBytes = imageBlob.getBytes(1, (int) imageBlob.length());
As BalusC noted in his comment, you'd better use:
InputStream binaryStream = resultSet.getBinaryStream(yourBlobColumnIndex);
And then the code depends on how you are going to read and embed the image.