JPA查询

Pojo: UserDetails

EntityManager: entityManager

1. Ceate Criteria

CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<UserDetails> criteria = builder.createQuery(UserDetails.class);

2. Compose SQL

    1) table

Root<UserDetails> userDetailsTable = criteria.from(UserDetails.class);

    2) Condition

Path<UserDetails> uId = userDetailsTable.get("userId");
Predicate condition = builder.equal(uId, userId);
criteria.where(condition);

3. result

return entityManager.createQuery(criteria).getSingleResult();