案例50-crm练习dao层的抽取BaseDao
1 抽取BaseDao
2 BaseDao设计思路
3 BaseDao接口书写
package www.test.dao; import java.io.Serializable; import java.util.List; import org.hibernate.criterion.DetachedCriteria; public interface BaseDao<T> { //增 void save(T t); //删 void delete(T t); //删 Serializable包括了8大包装类型 void delete(Serializable id); //改 void update(T t); //查 根据id查询 T getById(Serializable id); //查 符合条件的总记录数 Integer getTotalCount(DetachedCriteria dc); //查 查询分页列表数据 List<T> getPageList(DetachedCriteria dc,Integer start,Integer pageSize); }
4 BaseDao的实现类
package www.test.dao.impl; import java.io.Serializable; import java.lang.reflect.ParameterizedType; import java.util.List; import org.hibernate.criterion.DetachedCriteria; import org.hibernate.criterion.Projections; import org.springframework.orm.hibernate5.support.HibernateDaoSupport; import www.test.dao.BaseDao; public class BaseDaoImpl<T> extends HibernateDaoSupport implements BaseDao<T> { private Class clazz; // 用于接收运行期泛型类型 public BaseDaoImpl() { // 获得当前类型的带有泛型类型的父类 // this.getClass().getGenericSuperclass();运行在BaseDaoImpl的儿子(谁继承了它) // 所以它的父类就是BaseDaoImpl ParameterizedType ptClass = (ParameterizedType) this.getClass().getGenericSuperclass(); // 获得运行期的泛型类型 clazz = (Class) ptClass.getActualTypeArguments()[0]; } @Override public void save(T t) { super.getHibernateTemplate().save(t); } @Override public void delete(T t) { super.getHibernateTemplate().delete(t); } @Override public void delete(Serializable id) { // 先获取,然后在删除 T t = this.getById(id); super.getHibernateTemplate().delete(t); } @Override public void update(T t) { super.getHibernateTemplate().update(t); } @Override public T getById(Serializable id) { return (T) super.getHibernateTemplate().get(clazz, id); } @Override public Integer getTotalCount(DetachedCriteria dc) { // 设置查询聚合函数,总记录数 dc.setProjection(Projections.rowCount()); List<Long> list = (List<Long>) super.getHibernateTemplate().findByCriteria(dc); // 清空之前设置的聚合函数 dc.setProjection(null); if (list != null && list.size() > 0) { Long count = list.get(0); return count.intValue(); } else { return null; } } @Override public List<T> getPageList(DetachedCriteria dc, Integer start, Integer pageSize) { List<T> list = (List<T>) super.getHibernateTemplate().findByCriteria(dc, start, pageSize); return list; } }
5 业务Dao中的应用
package www.test.dao; import www.test.domain.Customer; public interface CustomerDao extends BaseDao<Customer>{ }
package www.test.dao.impl; import www.test.dao.CustomerDao; import www.test.domain.Customer; public class CustomerDaoImpl extends BaseDaoImpl<Customer> implements CustomerDao{ }