JTA Bean Managed Transaction Example

package com.sapient.impl;

import javax.annotation.Resource;
import javax.ejb.Stateless;
import javax.ejb.TransactionManagement;
import javax.ejb.TransactionManagementType;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.transaction.UserTransaction;

import com.sapient.entities.Book;
import com.sapient.spec.BookDAO;

@Stateless
@TransactionManagement(TransactionManagementType.BEAN)
public class BookDAOEJB implements BookDAO{
   
    @PersistenceContext
    private EntityManager em;
   
    @Resource
    private UserTransaction userTransaction;

    @Override
   
    public void saveBook(Book b) {
        System.out.println("---- saveBook of BookDAOEJB called ----");
        try {
            userTransaction.begin();
            System.out.println("---- Begin User Trasanction ----");
            em.persist(b);
            userTransaction.commit();
            System.out.println("---- Commit User Trasanction ----");
        } catch (Exception e) {   
            e.printStackTrace();
            try {
                userTransaction.rollback();
            } catch (Exception e1) {               
                e1.printStackTrace();
            }           
        }        
    }

    @Override
    public Book findBookById(String id) {
        Book bookFromDB = em.find(Book.class, id);
        System.out.println("---- BookDAO EJB Loading book with id "+id);
        return bookFromDB;
    }

}