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Enterprise Średniozaawansowany

JNDI Lookup vs CDI Injection

Replace fragile JNDI string lookups with type-safe CDI injection for container-managed resources.

Porównanie kodu
✕ Java EE 
public class OrderService {
    private DataSource ds;

    public void init() throws NamingException {
        InitialContext ctx = new InitialContext();
        ds = (DataSource) ctx.lookup(
            "java:comp/env/jdbc/OrderDB");
    }

    public List<Order> findAll()
            throws SQLException {
        try (Connection con = ds.getConnection()) {
            // query orders
        }
    }
}
✓ Jakarta EE 8+ 
@ApplicationScoped
public class OrderService {
    @Inject
    @Resource(name = "jdbc/OrderDB")
    DataSource ds;

    public List<Order> findAll()
            throws SQLException {
        try (Connection con = ds.getConnection()) {
            // query orders
        }
    }
}
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Dlaczego nowoczesne podejście wygrywa
🔒

Type-safe wiring

Injection errors are caught at deployment time, not at runtime via string lookups.

🗑️

No boilerplate

Eliminates InitialContext creation, JNDI name strings, and NamingException handling.

🧪

Testable

Dependencies are injected fields, easily replaced with mocks in unit tests.

Stare podejście
JNDI Lookup
Nowoczesne podejście
CDI @Inject
Od JDK
11
Poziom trudności
Średniozaawansowany
Wsparcie JDK
JNDI Lookup vs CDI Injection
Dostępne

Widely available since Jakarta EE 8 / Java 11

Jak to działa

The traditional JNDI pattern forces you to use string-based resource names, handle NamingException, and manage an InitialContext. CDI injection with @Inject (or @Resource for container resources) lets the container wire dependencies automatically. Typos become compile-time errors, and classes are easier to test because dependencies can be injected directly.

Powiązana dokumentacja
Jakarta CDI Specification ↗ Jakarta Annotations — @Resource ↗
Powiązane wzorce
Enterprise Średniozaawansowany

EJB versus CDI

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());
    }
}
Najedź, aby zobaczyć nową wersję ➜
JDK 11+ →
Enterprise Średniozaawansowany

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();
}
Najedź, aby zobaczyć nową wersję ➜
JDK 11+ →
Enterprise Średniozaawansowany

Singleton EJB vs CDI @ApplicationScoped

Java EE
@Singleton
@Startup
@ConcurrencyManagement(
    ConcurrencyManagementType.CONTAINER)
public class ConfigCache {
    private Map<String, String> cache;

    @PostConstruct
    public void load() {
        cache = loadFromDatabase();
    }

    @Lock(LockType.READ)
    public String get(String key) {
        return cache.get(key);
    }

    @Lock(LockType.WRITE)
    public void refresh() {
        cache = loadFromDatabase();
    }
}
Jakarta EE 8+
@ApplicationScoped
public class ConfigCache {
    private volatile Map<String, String> cache;

    @PostConstruct
    public void load() {
        cache = loadFromDatabase();
    }

    public String get(String key) {
        return cache.get(key);
    }

    public void refresh() {
        cache = loadFromDatabase();
    }
}
Najedź, aby zobaczyć nową wersję ➜
JDK 11+ →
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