Why I cannot cast oracle BLOB from native java Blob

Question

I am reading file from ResultSet and it's required to save file into Oracle Database.

...
ResultSet rs = ...
java.sql.Blob myfile = rs.getBlob("field")
java.io.OutputStream os = ((oracle.sql.BLOB) myfile).getBinaryOutputStream();

I get get this error message

java.lang.ClassCastException

Any one have solution to this? Thanks!

netic · Accepted Answer · 2009-07-23 00:13:00Z

4

I have found the solution. I'd like to share with those who has this problem.

The code to get outputstream from oracle blob is:

java.io.OutputStream os = ((oracle.sql.BLOB) myBlob).setBinaryStream(1L);

setBinaryStream() is actually returning java.io.OutputStream object

answered Jul 23, 2009 at 0:13

netic

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1 Comment

admdrew Over a year ago

@ericbn Please do not edit the question in a way that changes its meaning/intent. Instead, add a comment indicating the way in which you think it should be changed.

Community · Accepted Answer · 2020-06-20 09:12:55Z

3

java.sql.Blob is an interface. Presumably the implementation returned in your ResultSet is a different implementation to oracle.sql.BLOB?

What does myfile.getClass() return?

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Dec 18, 2008 at 22:52

Dan Vinton

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1 Comment

netic Over a year ago

I guess you are right. these two Blog are not compatible. I now use weblogic.jdbc.common.OracleBlob, it works fine. Although it is deprecated. But will keep it until we upgrade to Java 5 or higher.

Thilo · Accepted Answer · 2008-12-18 23:00:23Z

3

You seem to not have an oracle.sql.BLOB there (if you did, it should work, BLOB implements Blob). What does the ClassCastException say it is?

What version of Oracle and what version of the JDBC driver are you using?

getBinaryOutputStream is deprecated anyway, you should use setBinaryStream in the JDBC (3.0) interface, which probably removes the need to go to Oracle's internal class at all.

edited Dec 18, 2008 at 23:00

answered Dec 18, 2008 at 22:53

Thilo

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1 Comment

netic Over a year ago

You had a good tip on using "setBinaryStream" defined in JDBC 3.0. Unfortunately my application still using 1.4. Again will wait until we upgrade :)

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