"Morphia is a lightweight type-safe library for mapping Java objects to/from MongoDB:
Easy to use, and very lightweight; reflection is used once per type and cached for good performance.
Datastore and DAO access abstractions, or roll your own...
Type-safe, and Fluent Query support with (runtime) validation
Annotations based mapping behavior; there are no XML files.
Extensions: Validation (jsr303), and SLF4J Logging"