BaseDao设计思想

BaseDao.java

public interface BaseDao<T> {
    //增
    void save(T t);
    //删
    void delete(T t);
    //删
    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);
    
}

 BaseDaoImpl.java

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
        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) {
        getHibernateTemplate().save(t);
    }
    @Override
    public void delete(T t) {
        getHibernateTemplate().delete(t);
        
    }

    @Override
    //Serializable 对象序列化的接口，八大基本类型的父类
    public void delete(Serializable id) {
        T t = this.getById(id);//先取,再删
        getHibernateTemplate().delete(t);
    }

    @Override
    public void update(T t) {
        getHibernateTemplate().update(t);
    }

    @Override
    public T getById(Serializable id) {
        return (T) getHibernateTemplate().get(clazz, id);
    }

    @Override
    public Integer getTotalCount(DetachedCriteria dc) {
        //设置查询的聚合函数,总记录数
        dc.setProjection(Projections.rowCount());
        List<Long> list = (List<Long>) 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>) getHibernateTemplate().findByCriteria(dc, start, pageSize);
        return list;
    }

}

CustomerDao.java

public interface CustomerDao  extends BaseDao<Customer>{

}

CustomerDaoImpl.java

public class CustomerDaoImpl extends BaseDaoImpl<Customer> implements  CustomerDao{

}