package example;
import javax.annotation.Resource;
import javax.persistence.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.transaction.NotSupportedException;
import javax.transaction.RollbackException;
import javax.transaction.UserTransaction;
import java.io.*;
public class RegistrationServlet extends HttpServlet {
// This injects the default entity manager factory
@PersistenceUnit
private EntityManagerFactory emf;
// This injects a user transaction object.
@Resource
private UserTransaction utx;
public void service (HttpServletRequest req , HttpServletResponse resp)
throws ServletException, IOException {
try {
// begin a tx using utx b'cos we are using JTA EM.
utx.begin();
} catch (Exception e) {
throw new ServletException(e);
}
// create an entity manager in service() so that only
// this thread uses it.
// More over, we create EM after utx.begin(), so that we don't
// have to call em.joinTransaction().
EntityManager em = emf.createEntityManager();
try {
resp.setContentType("text/html");
PrintWriter out = resp.getWriter();
out.println(" New User Registartion " +
" ");
String name = req.getParameter("name");
String password = req.getParameter("password");
UserCredential credential = new UserCredential(name, password);
// em.persist makes the new object as persistent and managed.
em.persist(credential);
out.println("Successfully created the new user. " +
"Click here to login.");
out.println(" ");
// commit the transaction,
// b'cos web container rollbacks unfinished tx at the end of request
utx.commit();
} catch (Exception e) {
try {
utx.rollback();
} catch (Exception ee) {
// log the exception and continue
}
throw new ServletException(e);
} finally {
// close the em so that provider can release resources.
em.close();
}
}
public void init( ServletConfig config) throws ServletException {
super.init(config);
}
}