Current multipart provider stores the whole request in memory which is not good if one has to process large requests. Instead of writing an own temporary storage functionality I suggest using mime4j which already has this. Also makes parsing a lot easier because it does it alone.

The provided patch modifies the multipart provider to build upon mime4j. I run the resteasy tests for multipart provider they succeed with the new implementation.

mime4j - http://james.apache.org/mime4j/
mime4j apidocs - http://james.apache.org/mime4j/apidocs/