I have ported earlier XEP-0153: vCard-Based Avatars protocol implementation for Smack 4.2.0-beta. It provides the persistent storage support for avatar; and VCard auto-download option. Attached is the source.
Smack Development Team: You are welcome to include this feature in your future Smack library release. Some of the improvement in this release can be used in earlier release.
avatar_smack_4.2.zip (16722 Bytes)