SSH查询出现空指针异常

1.noticeDaoImpl.javapackage com.HRM.dao.Impl;import java.util.List;import org.springframework.orm.hibernate3.support.HibernateDaoSupport;import com.HRM.dao.noticeDao;import com.HRM.entity.Notice;public class noticeDaoImpl extends HibernateDaoSupport implements noticeDao {    @Override    public List<Notice> findAllNotice() {        List<Notice> list = getHibernateTemplate().find("from Notice");        return list;    }    }2.noticeServiceImpl.javapackage com.HRM.Service.Impl;import java.util.List;import com.HRM.dao.noticeDao;import com.HRM.entity.Notice;import com.opensymphony.xwork2.ActionSupport;public class noticeServiceImpl extends ActionSupport implements noticeService{    private noticeDao ndao;        @Override    public List<Notice> findAllNotice() {        return ndao.findAllNotice();    }                public noticeDao getNdao() {        return ndao;    }    public void setNdao(noticeDao ndao) {        this.ndao = ndao;    }}3.noticeAction.javapackage com.HRM.action;import java.util.List;import javax.servlet.http.HttpSession;import org.apache.struts2.ServletActionContext;import com.HRM.Service.Impl.noticeService;import com.HRM.entity.Notice;import com.opensymphony.xwork2.ActionSupport;public class noticeAction extends ActionSupport {    private noticeService nser;            HttpSession session = ServletActionContext.getRequest().getSession();    @Override    public String execute() throws Exception {        List<Notice> list = nser.findAllNotice();        if(list.size()>0){            session.setAttribute("notice",list);            return SUCCESS;        }        return ERROR;    }    public noticeService getNser() {        return nser;    }    public void setNser(noticeService nser) {        this.nser = nser;    }}