Hibernate stores Calendar as int when using SQLite

I am using Hibernate 4.3.8 along with a SQLite database (sqlite-jdbc-3.8.7.jar). Some of the mapped objects contain Calendar-attributes, e.g. startDate and endDate. After Hibernate got problems with reading dates in the format yyyy-MM-dd (e.g. 2015-01-01), I added the following line to hibernate.cfg.xml:

<property name="connection.date_string_format">yyyy-MM-dd</property>

Reading from the database works now, but when I save an object, Hibernate should save the date in the correct format but saves the time in milliseconds since 1970. After that, reading from the database again results in an error, since the columns now have values like 1427410800105, which are of course not the right format. Btw., I'm using the SQLiteDialect from here, there should be nothing wrong with that.

Are there maybe some annotations that can help me?

Personally, I only want to change some things in the configuration or in the dialect, I don't want to go through all my objects and do changes there.