maven 里模块拆分时， 我dao层的值传不进去service层

Running com.mycompany.app.service.UserServiceTest
**********service 层testQueryPassword******开始******
Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.081 sec <<< FAILURE!
testQueryPassword(com.mycompany.app.service.UserServiceTest) Time elapsed: 0.022 sec <<< ERROR!
java.lang.NullPointerException

    public String getUserPassword(String userName) {
        String name = "";
        Session session = null;
        try {
            session = HibernateUtils.getSession();
            session.beginTransaction();

            List result =  session.createQuery("select password from User where name = :name").setParameter("name", userName).list();

            if(result !=null && result.size()>0) {
                name = (String) result.get(0);
            } else {
                name = "null";
            }

            System.out.println("****************************");
            System.out.println(name);
            session.getTransaction().commit();
        }catch(Exception e) {
            e.printStackTrace();
            session.getTransaction().rollback();
        }finally {
            HibernateUtils.closeSession(session);
        }
        return "zhanshan";
    }


}



//service层

package com.mycompany.app.service;

import com.mycompany.app.dao.UserDao;

public class UserServiceImpl implements UserService {
    private UserDao userdao;
    public String getUserPassword(String name) {
        // TODO Auto-generated method stub
        return userdao.getUserPassword(name);
    }

}

@Autowired

spring框架，service 里没有注入dao啊@autowired

package com.mycompany.app.service;

import com.mycompany.app.dao.UserDao;
@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserDao userdao;
    public String getUserPassword(String name) {
        // TODO Auto-generated method stub
        return userdao.getUserPassword(name);
    }

}