হোম / Enterprise / EJB versus CDI
Enterprise মধ্যম

EJB versus CDI

Replace heavyweight EJBs with lightweight CDI beans for dependency injection and transactions.

কোড তুলনা
✕ Java EE 
@Stateless
public class OrderEJB {
    @EJB
    private InventoryEJB inventory;

    public void placeOrder(Order order) {
        // container-managed transaction
        inventory.reserve(order.getItem());
    }
}
✓ Jakarta EE 8+ 
@ApplicationScoped
public class OrderService {
    @Inject
    private InventoryService inventory;

    @Transactional
    public void placeOrder(Order order) {
        inventory.reserve(order.getItem());
    }
}
এই কোডে সমস্যা দেখছেন? আমাদের জানান।
কেন আধুনিক পদ্ধতি ভালো
🪶

Lightweight

CDI beans are plain Java classes with no EJB-specific interfaces or descriptors.

💉

Unified injection

@Inject works for every managed bean, JAX-RS resources, and Jakarta EE components alike.

🧪

Easy unit testing

Plain classes without EJB proxy overhead are straightforward to instantiate and mock.

পুরনো পদ্ধতি
EJB
আধুনিক পদ্ধতি
CDI Bean
JDK থেকে
11
কঠিনতা
মধ্যম
JDK সমর্থন
EJB versus CDI
উপলব্ধ

Widely available since Jakarta EE 8 / Java 11

কীভাবে কাজ করে

CDI (Contexts and Dependency Injection) provides the same dependency injection and transaction management as EJBs, but as plain Java classes with no container-specific interfaces or superclasses. Scopes like @ApplicationScoped and @RequestScoped control lifecycle, and @Transactional replaces mandatory EJB transaction semantics.

সম্পর্কিত ডকুমেন্টেশন
Jakarta CDI Specification ↗ Jakarta Transactions — @Transactional ↗
প্রমাণ
প্রমাণ সোর্স দেখুন ↗
সম্পর্কিত প্যাটার্ন
Enterprise মধ্যম

Servlet versus JAX-RS

Java EE
@WebServlet("/users")
public class UserServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req,
                         HttpServletResponse res)
            throws ServletException, IOException {
        String id = req.getParameter("id");
        res.setContentType("application/json");
        res.getWriter().write("{\"id\":\"" + id + "\"}");
    }
}
Jakarta EE 8+
@Path("/users")
public class UserResource {
    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Response getUser(
            @QueryParam("id") String id) {
        return Response.ok(new User(id)).build();
    }
}
আধুনিক দেখতে হোভার করুন ➜
JDK 11+ →
Enterprise মধ্যম

JDBC versus JPA

Java EE
String sql = "SELECT * FROM users WHERE id = ?";
try (Connection con = dataSource.getConnection();
     PreparedStatement ps =
             con.prepareStatement(sql)) {
    ps.setLong(1, id);
    ResultSet rs = ps.executeQuery();
    if (rs.next()) {
        User u = new User();
        u.setId(rs.getLong("id"));
        u.setName(rs.getString("name"));
    }
}
Jakarta EE 8+
@PersistenceContext
EntityManager em;

public User findUser(Long id) {
    return em.find(User.class, id);
}

public List<User> findByName(String name) {
    return em.createQuery(
        "SELECT u FROM User u WHERE u.name = :name",
        User.class)
        .setParameter("name", name)
        .getResultList();
}
আধুনিক দেখতে হোভার করুন ➜
JDK 11+ →
Language প্রাথমিক

Records for data classes

Java 8
public class Point {
    private final int x, y;
    public Point(int x, int y) { ... }
    public int getX() { return x; }
    public int getY() { return y; }
    // equals, hashCode, toString
}
Java 16+
public record Point(int x, int y) {}
আধুনিক দেখতে হোভার করুন ➜
JDK 16+ →