Exception Translation

@Service
@Transactional
public class UserService {

    @PersistenceContext
    private EntityManager entityManager;

    public User findById(Long id) {
        try {
            User user = entityManager.find(User.class, id);
            if (user == null) {
                throw new EntityNotFoundException("User not found: " + id);
            }
            return user;
        } catch (EntityNotFoundException ex) {
            // Automatically translated to JpaObjectRetrievalFailureException
            throw ex;
        }
    }

    public void updateUser(User user) {
        try {
            entityManager.merge(user);
        } catch (OptimisticLockException ex) {
            // Automatically translated to JpaOptimisticLockingFailureException
            throw ex;
        }
    }
}

// Entity not found
class JpaObjectRetrievalFailureException extends ObjectRetrievalFailureException {
    JpaObjectRetrievalFailureException(EntityNotFoundException ex);
}

// Optimistic locking failure
class JpaOptimisticLockingFailureException extends ObjectOptimisticLockingFailureException {
    JpaOptimisticLockingFailureException(OptimisticLockException ex);
}

// Uncategorized errors
class JpaSystemException extends UncategorizedDataAccessException {
    JpaSystemException(RuntimeException ex);
}

// Optimistic locking violation
class ObjectOptimisticLockingFailureException extends OptimisticLockingFailureException {

    ObjectOptimisticLockingFailureException(Class<?> persistentClass, Object identifier);
    ObjectOptimisticLockingFailureException(String persistentClassName, Object identifier);
    ObjectOptimisticLockingFailureException(
        Class<?> persistentClass, Object identifier, String msg, Throwable cause);

    Class<?> getPersistentClass();
    String getPersistentClassName();
    Object getIdentifier();
}

// Object not found
class ObjectRetrievalFailureException extends DataRetrievalFailureException {

    ObjectRetrievalFailureException(Class<?> persistentClass, Object identifier);
    ObjectRetrievalFailureException(String persistentClassName, Object identifier);
    ObjectRetrievalFailureException(
        Class<?> persistentClass, Object identifier, String msg, Throwable cause);

    Class<?> getPersistentClass();
    String getPersistentClassName();
    Object getIdentifier();
}

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;

@ControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(JpaObjectRetrievalFailureException.class)
    public ResponseEntity<ErrorResponse> handleObjectNotFound(
            JpaObjectRetrievalFailureException ex) {
        ErrorResponse error = new ErrorResponse();
        error.setMessage("Entity not found: " +
            ex.getPersistentClassName() + " with id " + ex.getIdentifier());
        error.setStatus(HttpStatus.NOT_FOUND.value());

        return ResponseEntity.status(HttpStatus.NOT_FOUND).body(error);
    }

    @ExceptionHandler(JpaOptimisticLockingFailureException.class)
    public ResponseEntity<ErrorResponse> handleOptimisticLocking(
            JpaOptimisticLockingFailureException ex) {
        ErrorResponse error = new ErrorResponse();
        error.setMessage("The entity was modified by another transaction. " +
            "Please reload and try again.");
        error.setStatus(HttpStatus.CONFLICT.value());

        return ResponseEntity.status(HttpStatus.CONFLICT).body(error);
    }

    @ExceptionHandler(JpaSystemException.class)
    public ResponseEntity<ErrorResponse> handleJpaSystemException(
            JpaSystemException ex) {
        ErrorResponse error = new ErrorResponse();
        error.setMessage("A system error occurred: " + ex.getMessage());
        error.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());

        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(error);
    }

    @ExceptionHandler(DataAccessException.class)
    public ResponseEntity<ErrorResponse> handleDataAccessException(
            DataAccessException ex) {
        ErrorResponse error = new ErrorResponse();
        error.setMessage("Data access error: " + ex.getMessage());
        error.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());

        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(error);
    }
}

@Service
@Transactional
public class OrderService {

    @PersistenceContext
    private EntityManager entityManager;

    public Order createOrder(OrderRequest request) {
        try {
            // Verify product exists
            Product product = entityManager.find(Product.class, request.getProductId());
            if (product == null) {
                throw new ObjectRetrievalFailureException(
                    Product.class, request.getProductId());
            }

            // Create order
            Order order = new Order();
            order.setProduct(product);
            order.setQuantity(request.getQuantity());

            entityManager.persist(order);
            return order;

        } catch (EntityNotFoundException ex) {
            // Translated to JpaObjectRetrievalFailureException
            throw ex;
        } catch (PersistenceException ex) {
            // Translated to JpaSystemException
            throw ex;
        }
    }

    public void updateOrder(Long orderId, int newQuantity) {
        try {
            Order order = entityManager.find(Order.class, orderId);
            if (order == null) {
                throw new ObjectRetrievalFailureException(Order.class, orderId);
            }

            order.setQuantity(newQuantity);
            entityManager.merge(order);

        } catch (OptimisticLockException ex) {
            // Translated to JpaOptimisticLockingFailureException
            throw new ObjectOptimisticLockingFailureException(
                Order.class, orderId,
                "Order was modified by another user", ex
            );
        }
    }
}

import org.springframework.orm.hibernate5.HibernateExceptionTranslator;
import org.springframework.jdbc.support.SQLErrorCodeSQLExceptionTranslator;
import org.springframework.jdbc.support.SQLExceptionTranslator;

@Configuration
public class HibernateConfig {

    @Bean
    public HibernateExceptionTranslator hibernateExceptionTranslator(
            DataSource dataSource) {
        HibernateExceptionTranslator translator = new HibernateExceptionTranslator();

        // Use custom JDBC exception translator
        SQLExceptionTranslator jdbcTranslator =
            new SQLErrorCodeSQLExceptionTranslator(dataSource);
        translator.setJdbcExceptionTranslator(jdbcTranslator);

        return translator;
    }
}

class HibernateExceptionTranslator implements PersistenceExceptionTranslator {

    // Set JDBC exception translator
    void setJdbcExceptionTranslator(SQLExceptionTranslator translator);

    // Translate exception
    DataAccessException translateExceptionIfPossible(RuntimeException ex);
}

@FunctionalInterface
interface PersistenceExceptionTranslator {

    // Returns null if exception should not be translated
    DataAccessException translateExceptionIfPossible(RuntimeException ex);
}