Firs of all you have to decide which part of j2ee you want to use and why ?for example you can consider the follwing parameter to select possible technology.
1- are your application is going to be a distributed application or not.if it 's not a distributed app I suggest no to use EJB part of J2EE .
2- if it's going to be a web application ,you can use an MVC Framework such as Struts for web application and for Data Access Layer you can use Hibernate for your OR Mapping.
if there is another issue please let me know.