Spring结合JPA设计通用的BaseDao实现完全的面向接口编程

╰+攻爆jí腚メ 2022-05-17 02:07 221阅读 0赞

这是我们团队小项目中设计的通用BaseDao：

public interface BaseDao<T> {
        /**
         * 添加实体类
         * @param t
         * @return
         */
        public T add(T t);
    
        /**
         * 更新实体类
         * @param t
         * @return
         */
        public T update(T t);
    
        /**
         * 根据主键ID删除实体类
         * @param id
         */
        public void delete(Serializable id);
    
        /**
         * 根据JPQL语句更新或删除操作
         * @param jpql
         * @param obj
         */
        public int executeUpdate(String jpql,Object... obj);
    
        /**
         * 根据主键ID查找单个实体类
         * @param id
         * @return
         */
        public T load(Serializable id);
    
        /**
         * 根据JPQL语句查询单个实体类
         * @param jpql
         * @param obj（参数可有可无）
         * @return
         */
        public T load(String jpql,Object... obj);
    
        /**
         * 查找所有的实体类
         * @return
         */
        public List<T> findAll();
    
        /**
         * 根据JPQL语句查询集合实体类
         * @param jpql
         * @param obj（参数可有可无）
         * @return
         */
        public List<T> find(String jpql,Object... obj);
    
        /**
         * 聚合查询
         * @param jpql
         * @param obj
         * @return
         */
        public Object findByAggregate(String jpql,Object... obj);
    
        /**
         * 查找总记录数
         * @return
         */
        public int count();
    
        /**
         * 根据JPQL语句查询记录数
         * @param jpql
         * @param obj
         * @return
         */
        public int count(String jpql,Object... obj);
    
        /**
         * 分页查询集合实体类
         * @param firstIndex
         * @param maxResults
         * @return
         */
        public List<T> findPage(Integer firstIndex, Integer maxResults);
    
        /**
         * 根据JPQL语句查询集合实体类
         * @param firstIndex
         * @param maxResults
         * @param jpql
         * @param obj
         * @return
         */
        public List<T> findPage(Integer firstIndex, Integer maxResults,String jpql,Object... obj);
    
    
        public Page findPage(Page page,String jpql,Object... obj);
    
    }

BaseDao的基础实现类AbstractBaseDao：

public abstract class AbstractBaseDao<T> implements BaseDao<T> {
    
        @PersistenceContext
        private EntityManager em;
    
        private Class<T> clazz = null;
    
        public AbstractBaseDao(){
            ParameterizedType pt = (ParameterizedType) this.getClass().getGenericSuperclass();
            this.clazz = (Class<T>) pt.getActualTypeArguments()[0];
        }
    
    
        @Override
        public T add(T t) {
            em.persist(t);
            return t;
        }
    
        @Override
        public T update(T t) {
            return em.merge(t);
        }
    
    
        @Override
        public void delete(Serializable id) {
            T t = em.getReference(clazz, id);
            em.remove(t);
        }
    
        @Override
        public int executeUpdate(String jpql, Object... obj) {
            Query query = em.createQuery(jpql);
            if(obj.length > 0){
                for (int i = 0; i < obj.length; i++) {
                    query.setParameter((i+1),obj[i]);
                }
            }
            return query.executeUpdate();
        }
    
        @Override
        public T load(Serializable id) {
            return em.find(clazz, id);
        }
    
        @Override
        public T load(String jpql, Object... obj) {
            try{
                Query query = em.createQuery(jpql);
                if(obj.length > 0){
                    for (int i = 0; i < obj.length; i++) {
                        query.setParameter((i+1),obj[i]);
                    }
                }
                return (T) query.getSingleResult();
            }catch (Exception e){
              return null;
            }
        }
    
        @Override
        public List<T> findAll() {
            return em.createQuery("from "+clazz.getSimpleName()).getResultList();
        }
    
        @Override
        public List<T> find(String jpql, Object... obj) {
            try{
                Query query = em.createQuery(jpql);
                if(obj.length > 0){
                    for (int i = 0; i < obj.length; i++) {
                        query.setParameter((i+1),obj[i]);
                    }
                }
               return query.getResultList();
            }catch (Exception e){
                return null;
            }
        }
    
        @Override
        public Object findByAggregate(String jpql, Object... obj) {
            Query query = em.createQuery(jpql);
            if(obj.length > 0){
                for (int i = 0; i < obj.length; i++) {
                    query.setParameter((i+1),obj[i]);
                }
            }
            Object result = query.getSingleResult();
            return result;
        }
    
        @Override
        public int count() {
            Long num = (Long) em.createQuery("select count(*) from "+clazz.getSimpleName()).getSingleResult();
            return num.intValue();
        }
    
        @Override
        public int count(String jpql,Object... obj) {
            try{
                Query query = em.createQuery(jpql);
                if(obj.length > 0){
                    for (int i = 0; i < obj.length; i++) {
                        query.setParameter((i+1),obj[i]);
                    }
                }
                Long num = (Long)query.getSingleResult();
                return num.intValue();
            }catch (Exception e){
                return 0;
            }
        }
    
        @Override
        public List<T> findPage(Integer firstIndex, Integer maxResults) {
            return em.createQuery("from "+clazz.getSimpleName()).setFirstResult(firstIndex).setMaxResults(maxResults).getResultList();
        }
    
        @Override
        public List<T> findPage(Integer firstIndex, Integer maxResults,String jpql,Object... obj) {
            try{
                Query query = em.createQuery(jpql);
                if(obj.length > 0){
                    for (int i = 0; i < obj.length; i++) {
                        query.setParameter((i+1),obj[i]);
                    }
                }
                query.setFirstResult(firstIndex).setMaxResults(maxResults);
                return query.getResultList();
            }catch (Exception e){
                return null;
            }
    
        }
    
        @Override
        public Page<T> findPage(Page page, String jpql, Object... obj) {
            Query query = em.createQuery(jpql);
            if(obj.length > 0){
                for (int i = 0; i < obj.length; i++) {
                    query.setParameter((i+1),obj[i]);
                }
            }
            int total = ((Long)query.getSingleResult()).intValue();
            page.setItemTotal(total);
            query.setFirstResult(page.getFirstIndex()).setMaxResults(page.getPageCount());
            List<T> list = query.getResultList();
            page.setItems(list);
            return page;
        }
    
    }

这里我们AbstractBaseDao设计为abstract ，因为我们不想让他被实例化。IOC作为Spring中的核心技术之一使用它可以实现完全的面向接口编程，所以我们需要设计接口。这样我们就可以在service层中使用接口注入。

现在我们来设计接口，如果我现在想要做一个订单的持久层OrderDao要怎么做。

public interface OrderDao extends BaseDao<Order> {
    
        List<Order> findOrderByStoreId(String storeId);
    
        List<Order> findOrderByStatus(String storeId,Integer status);
    
        int getActiveOrderCount(String storeId);
    
        int getNewOrderCount(String storeId);
    
        int getOrderCount(String storeId);
    
        List<Order> findOrderByStoreId(String storeId,Integer page, Integer pageSize);
    
        List<Order> findOrderByStatus(String storeId, Integer status, Integer page, Integer pageSize);
    
        int getOrderByStatusCount(String storeId, Integer status);
    }

然后写一个实现OrderDao的OrderDaoImpl：

@Repository
    public class OrderDaoImpl extends AbstractBaseDao<Order> implements OrderDao {
    
        public List<Order> findOrderByStoreId(String storeId){
            List<Order> orders = this.find("SELECT o FROM Order o WHERE o.storeId = ? order by o.createTime desc", storeId);
            return orders;
        }
    
        @Override
        public List<Order> findOrderByStatus(String storeId,Integer status) {
            List<Order> orders = this.find("SELECT o FROM Order o WHERE o.storeId = ? and o.status = ? order by o.createTime desc", storeId, status);
            return orders;
        }
    
        @Override
        public int getActiveOrderCount(String storeId) {
            return this.count("SELECT count(o) FROM Order o WHERE o.storeId = ? and o.status in (1,2)", storeId);
        }
    
        @Override
        public int getNewOrderCount(String storeId) {
            return this.count("SELECT count(o) FROM Order o WHERE o.storeId = ? and o.status = 0", storeId);
        }
    
        @Override
        public int getOrderCount(String storeId) {
            return this.count("SELECT count(o) FROM Order o WHERE o.storeId = ?", storeId);
        }
    
        @Override
        public List<Order> findOrderByStoreId(String storeId, Integer page, Integer pageSize) {
            return this.findPage((page -1) * pageSize, pageSize, "SELECT o FROM Order o WHERE o.storeId = ? order by o.createTime desc, o.id", storeId);
        }
    
        @Override
        public List<Order> findOrderByStatus(String storeId, Integer status, Integer page, Integer pageSize) {
            return this.findPage((page -1) * pageSize, pageSize, "SELECT o FROM Order o WHERE o.storeId = ? and o.status = ? order by o.createTime desc, o.id", storeId, status);
        }
    
        @Override
        public int getOrderByStatusCount(String storeId, Integer status) {
            return this.count("SELECT count(o) FROM Order o WHERE o.storeId = ? and o.status = ?", storeId, status);
        }
    }

然后我们在service层中就可以直接注入。

@Service
    public class OrderServiceImpl implements OrderService {
    
        @Autowired
        private OrderDao orderDao;
      
        //.....
    
    }

这样就可以完全实现面向接口编程。