FileOutputStream Not supporting

Hello , i am trying to upload a file to other server through gxt, i
got a error which telling that

"java.io.FileOutputStream is not supported by Google App Engine's
Java runtime environment" how can i resolve this problem??

or is there any altrnate way ?
please help me :(

Regards
Arun Paul

--
You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group.
To post to this group, send email to google-web-toolkit@googlegroups.com.
To unsubscribe from this group, send email to google-web-toolkit+unsubscribe@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.