JaQu
JaQu stands for Java Query and allows to access databases using pure Java. JaQu provides a fluent interface (or internal DSL) for building SQL statements. JaQu replaces SQL, JDBC, and persistence frameworks such as Hibernate. JaQu is something like LINQ for Java (LINQ stands for "language integrated query" and is a Microsoft .NET technology).
http://www.h2database.com/html/jaqu.html
They also have a nice list of similar projects on their website.
Querydsl
Querydsl (spell: query diesel) is a framework which enables the construction of statically typed SQL-like queries. Instead of writing queries as inline strings or externalizing them into XML files they can be constructed via a fluentDSL/API like Querydsl.
http://source.mysema.com/display/querydsl/Querydsl
jPersist
jPersist is an extremely powerful object-relational persistence API that is based on the active-record and data-mapper patterns.
eodsql
EoD SQL Allows for fast, simple binding between a Relation Database Query and Java objects.
EoD SQL stands for Ease of Development, the API's key concerns are being:
Lightweight Designed to be small with a low memory footprint
Very Fast By re-using all of it's data as much as possible.
Easy to work with Annotation based, no setup, config or XML files.
Powerful Write your own SQL rather than hope it generates what you want.
Stable
jlibs DAOPattern
J2EE DAO Pattern made easier
http://code.google.com/p/jlibs/wiki/DAOPattern
jOOQ
A simple and intuitive approach to interface your database with Java: jOOQ is Java Object Oriented Querying. jOOQ brings the relational world to Java without covering up its origins. jOOQ is relational. And object oriented. Just in a different way.
http://sourceforge.net/apps/trac/jooq http://sourceforge.net/projects/jooq
Torpedoquery
Finally you can now use your real classes to construct queries and use the power of your IDE to maintain and validate your queries. http://torpedoquery.org/