JPA 高级使用

lazy=true时，如何自动注入关联属性

例子1 DeaprtEntity  EmployeeEntity 举例说明

 DeaprtEntity  EmployeeEntity  1:n

@Transactional
    public DepartEtity getDepartById(int id) {
        // 1. touch相关懒加载字段
        DepartEntity depart= departRepository.findOne(id);
        Hibernate.initialize(depart.getEmployeeEntityList());
        // 2. 直接修改加载模式
//        DepartEntity depart = departRepository.getById(id);

//        List<EmployeeEntity> employeeList = depart.getEmployeeEntityList();
//        if (null != employeeList && employeeList .size()>0){
//            employeeList .get(0);
//        }
        return depart;
    }

例子2 CompanyEntity   DeaprtEntity  EmployeeEntity 举例说明

CompanyEntity   DeaprtEntity   1:n
 DeaprtEntity  EmployeeEntity  1:n

EmployeeEntity设置为lazy，返回结果DepoyEntity中自动注入employeeList

@Transactional
@Override
public Page<DepartEntity> getSoundSourceEntityList(final Integer companyId,  final String name, Pageable page) {
    Page<DepartEntity> result =  departRepository.findAll(new Specification<DepartEntity>() {
        @Override
        public Predicate toPredicate(Root<DepartEntity> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
            // TODO: 优化
            Predicate conjunction = cb.conjunction();
            // 判断非count(1)查询，设置连接
            if (query.getResultType() == Depart.class)
                root.fetch("employeeList", JoinType.LEFT);
            if (companyId != null) {
               conjunction = cb.and(conjunction, cb.isMember(companyId , root.<Collection<Integer>>get("companyEntities")));
            }
            if (!StringUtils.isEmpty(name)) {
                conjunction = cb.like(root.get("name"), "%" + name + "%");
            }
            query.where(conjunction);
            query.orderBy(cb.desc(root.get("createTime").as(Timestamp.class)));
            return query.getRestriction();
        }
    }, page);

    return result;
}