将Criteria API + JPA规范与IN表达式和Spring Boot配合使用

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import javax.persistence.EntityManager;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import java.util.List;

@Service
public class UserService {

    @Autowired
    private EntityManager entityManager;

    public List<User> findUsersByIds(List<Long> ids) {
        CriteriaBuilder cb = entityManager.getCriteriaBuilder();
        CriteriaQuery<User> cq = cb.createQuery(User.class);
        Root<User> user = cq.from(User.class);

        Predicate idPredicate = user.get("id").in(ids);
        cq.where(idPredicate);

        return entityManager.createQuery(cq).getResultList();
    }
}