一、BaseDao模板

public interface BaseDao<T> {
    
    public Serializable save(T entity); 

    public void delete(T entity);

    public void update(T entity);
    
    public List<T> find(T condition);
    
    public T findById(Serializable id);

    // 参数1：hqlString = from Users u where u.name like ? and u.telephone=?
    // 参数2：new Object[]{name,telephone,...}
    public List<T> getListByHQL(String hqlString, Object... values);

    public List<T> queryListObjectAllForPage(int pageSize, int page,
            String hqlString, Object... values);

    //单值查询   select count()
    public Object uniqueResult(String sqlString, Object... values);
    
    public Object uniqueResultForPages(String hqlString,int pageSize,int page, Object... values);
}

二、BaseDaoImpl模板

@Repository
public class BaseDaoImpl<T> implements BaseDao<T> {
    
    //@Resource   //官方的注解
    @Autowired
    private SessionFactory sessionFactory;
    
    protected Class<T> entityClass;

    public Session getCurrentSession() {
        return this.sessionFactory.getCurrentSession();
    }

    protected Class getEntityClass() {
        if (entityClass == null) {
            entityClass = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass())
                    .getActualTypeArguments()[0];
        }
        return entityClass;
    }

    public Serializable save(T entity) {
        return this.getCurrentSession().save(entity);

    }

    public void delete(T entity) {
        this.getCurrentSession().delete(entity);
    }

    public void update(T entity) {
        this.getCurrentSession().update(entity);
    }   

    public List<T> find(T condition) {
        Criteria criteria = this.getCurrentSession().createCriteria(getEntityClass());
        criteria.add(Example.create(condition));
        return criteria.list();
    }

    public T findById(Serializable id) {
        T load = (T) this.getCurrentSession().get(getEntityClass(), id);
        return load;
    }
    

    /**
     * <根据HQL语句，得到对应的list>
     * 
     * @param hqlString
     *            HQL语句
     * @param values
     *            不定参数的Object数组
     * @return 查询多个实体的List集合
     * @see com.itv.launcher.util.IBaseDao#getListByHQL(java.lang.String,
     *      java.lang.Object[])
     */
    public List<T> getListByHQL(String hqlString, Object... values) {
        Query query = this.getCurrentSession().createQuery(hqlString);
        if (values != null) {
            for (int i = 0; i < values.length; i++) {
                query.setParameter(i, values[i]);  //设置占位符的参数
            }
        }
        return query.list();
    }

    public List<T> queryListObjectAllForPage(int pageSize, int page, String hqlString, Object... values) {

        Query query = this.getCurrentSession().createQuery(hqlString);
        if (values != null) {
            for (int i = 0; i < values.length; i++) {
                query.setParameter(i, values[i]);
            }
        }
        query.setFirstResult((page - 1) * pageSize);
        query.setMaxResults(pageSize);
        return query.list();
    }

    public Object uniqueResult(String hqlString, Object... values) {
        Query query = this.getCurrentSession().createQuery(hqlString);
        if (values != null) {
            for (int i = 0; i < values.length; i++) {
                query.setParameter(i, values[i]);
            }
        }
        return query.uniqueResult();
    }
    
    public Object uniqueResultForPages(String hqlString, int pageSize,
            int page, Object... values) {
        Query query = this.getCurrentSession().createQuery(hqlString);
        if (values != null) {
            for (int i = 0; i < values.length; i++) {
                query.setParameter(i, values[i]);
            }
        }
        query.setFirstResult((page - 1) * pageSize);
        query.setMaxResults(pageSize);
        
        return query.uniqueResult();
    }
}

三、继承

public interface UserDao extends BaseDao<User> {}

public class UserDaoImpl extends BaseDaoImpl<User> implements UserDao {}