Convert String to Blob

String data = “hello world”;
java.sql.Blob blob = org.hibernate.Hibernate.createBlob(data.getBytes());

Convert Blob to String

byte[] bdata = blob.getBytes(1, (int)blob.length());
String data1 = new String(bdata);

if the length of blob exceeds the maxvalue for the int, then u can use CLOB format.To store large data we can use CLOB format and to store an image, use a BLOB data types.