DataNucleus supports persisting/retrieving objects to/from ODF documents (using the datanucleus-odf plugin, which makes use of the ODFDOM project). Simply specify your "connectionURL" as follows
replacing "myfile.ods" with your filename, which can be absolute or relative. This connects to a file on your local machine. You then create your PMF/EMF as normal and use JDO/JPA as normal.
The jars required to use DataNucleus ODF persistence are datanucleus-core, datanucleus-api-jdo/datanucleus-api-jpa, datanucleus-odf and odftoolkit
Things to bear in mind with ODF usage :-
A typical spreadsheet has many rows of data. It contains no names of columns tying the data back to the input object (field names). DataNucleus allows an extension specified at class level called include-column-headers (should be set to true). When the table is then created it will include an extra row (the first row) with the column names from the metadata (or field names if no column names were defined). For example