如何使用getHibernateTemplate（）从SQL获取count（*）？

Question

我想从表中获取DEVICES的数量并在我的Html页面上显示结果，我有以下代码，当我运行此代码时，我在我的bean中得到Null指针异常：

DashboardDaoImp.java // Dao实现

public int getNumberOfDevices(){

    return DataAccessUtils.intResult(getHibernateTemplate().find("SELECT COUNT(DISTINCT deviceid) from Device"));
}

DashboardDao.java // Dao界面

public interface DashbordDao {

int getNumberOfDevices();

}

DashboardBoImp.java // Bo实现

DashbordDao dashbordDao;

@Override
public int getNumberOfDevices() {

    return dashbordDao.getNumberOfDevices();
}

DashboardBoImp.java // Bo界面

public interface DashbordBo {

int getNumberOfDevices();   
}

DashboardBean.java //我的bean

public int getNumberOfDevices()
    {
    samssnb_device = dashboardBo.getNumberOfDevices();

    return samssnb_device;
    }

//我的Html页面

<h3>#{dashbord.getNumberOfDevices()}<sup style="font-size: 20px"></sup></h3>
              <p>Number of devices </p>

//堆栈跟踪

Stack Trace Image