反射（DAO层的设计）<学习随笔>

DAO

public interface BaseDao<T> {

void save(T entity);

void delete(Integer id);

void update(T entity);

T getById(Integer id);

List<T> getByIds(Integer[] ids);

List<T> findAll();

PageBean getPageBean(int pageNum,HqlHelper hqlHelper);//分页

}

DAOIMPL

public abstract class BaseDaoImpl<T> implements BaseDao<T> {

@Resource

private SessionFactory sessionFactory;//session工厂

private Class<T> clazz;

public BaseDaoImpl(){

ParameterizedType pt = (ParameterizedType) this.getClass().getGenericSuperclass(); // 获取父类类名

this.clazz =(Class<T>) pt.getActualTypeArguments()[0]; //取出类

}

/*获取当前可用session*/

protected Session getSession() {

return sessionFactory.getCurrentSession();

}

@Override

public void save(T entity) {

getSession().save(entity);

}

@Override

public void delete(Integer id) {

Object obj = getById(id);

if(obj!=null){

getSession().delete(obj);

}

}

@Override

public void update(T entity) {

getSession().update(entity);

}

@Override

public T getById(Integer id) {

if(id==null){

return null;

}else{

return (T) getSession().get(clazz, id);

}

}

@Override

public List<T> getByIds(Integer[] ids) {

if(ids==null||ids.length==0){

return Collections.EMPTY_LIST;

}else{

return getSession().createQuery(//

"FROM"+clazz.getSimpleName()+"WHERE id IN (:ids)")//

.setParameterList("ids", ids)//

.list();

}

}

@Override

public List<T> findAll() {

return getSession().createQuery(//

"FROM " + clazz.getSimpleName())//

.list();

}