拿到某个用户的全部信息, 如果这个用户还有其他的相关内容都会被抓出来发给手机端
String jpql = "select admin from Admin admin where lower(admin.username) = lower(:username)";
考虑到和手机端的交互用JSON当然内容越少越好,提供二种解决办法:
1. 使用Tuple, 并将结果放入自己定义的AdminWrapper
public List<AdminWrapper> getAdminListByTuple() { //1: CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder(); //2: One of the JPA ways for getting only particular columns is to ask for a Tuple object. CriteriaQuery<Tuple> criteriaQuery = criteriaBuilder.createTupleQuery(); //3: Root<Admin> root = criteriaQuery.from(Admin.class); //4: criteriaQuery.multiselect( root.get("id"), root.get("username"), root.get("name") ); //5:条件 Predicate restrictions = criteriaBuilder.conjunction(); restrictions = criteriaBuilder.and(restrictions, criteriaBuilder.equal(root.get("id"), 1)); criteriaQuery.where(restrictions); criteriaQuery.orderBy(criteriaBuilder.desc(root.get("id"))); //5: TypedQuery<Tuple> query = entityManager.createQuery(criteriaQuery).setFlushMode(FlushModeType.COMMIT); //6 List<Tuple> tuples = query.getResultList(); AdminWrapper adminWrapper = null; List<AdminWrapper> lists = new ArrayList<AdminWrapper>(); for (Tuple t : tuples) { adminWrapper = new AdminWrapper(); adminWrapper.setId((Long)t.get(0)); adminWrapper.setUsername((String)t.get(1)); adminWrapper.setName((String)t.get(2)); lists.add(adminWrapper); } return lists; }
2. 直接使用AdminWrapper,前提是有构造方法
public AdminWrapper() { } public AdminWrapper (Long id, String username, String name) { this.id = id; this.username = username; this.name = name; } 然后 public List<AdminWrapper> getAdminListByT() { //1: CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder(); //2: One of the JPA ways for getting only particular columns is to ask for a Tuple object. CriteriaQuery<AdminWrapper> criteriaQuery = criteriaBuilder.createQuery(AdminWrapper.class); //3 Root<Admin> root = criteriaQuery.from(Admin.class); //4 criteriaQuery.multiselect( root.get("id"), root.get("username"), root.get("name") ); //5 TypedQuery<AdminWrapper> query = entityManager.createQuery(criteriaQuery).setFlushMode(FlushModeType.COMMIT); List<AdminWrapper> lists = query.getResultList(); return lists; }