How to manipulate a BLOB in Java?

Question

I have a DB procedure which returns a BLOB. Can anyone tell me how to manipulate the BLOB? Is there any specific API for this?

Answer 1

Is there any specific API for this ?

Sure, the JDBC API.

• Trail: JDBC™ Database Access

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You get hold of the Blob instance just as you get hold of any value from a result set. You should then use the get...- and set... methods on this Blob.

Here you basically have two options:

• Work with a byte-array:

  1. Get hold of a byte[] containing the data through Blob.getBytes
  2. Manipulate this byte-array
  3. Set it back using Blob.setBytes.
     
     
     

• Work with InputStream / OutputStream:

  1. Get hold a an InputStream through Blob.getBinaryStream
  2. Manipulate this stream as you see fit
  3. Use Blob.setBinaryStream.
     
     

An alternative approach is to skip messing with Blob in the first place, and instead use the second approach (with streams) directly through the ResultSet-interface.