byte bytes = /* something */;
String correspondingString = new String(bytes);
Got it now. So BLOB should be a byte in Java, not the String. So either I have to go for CLOB mapped to String in Java, or Go for BLOB and mapped it to byte in Java.
MySQL -- Java
BLOB --> byte
CLOB --> String.
Thanks you all. I can't update the DB now , so I have changed the filed to byte in Java mapping file and then converting it to String using new String(byte) after reading from DB.