@Autowired是按类型自动装配的，为什么在我这里会出现按名称自动装配的情况

@Repository
public final class UserDao implements IUserDao {
   public UserDao() {
       System.out.println("正在创建UserDao：" + this);
   }
}

@Repository
public class UserOracleDao implements IUserDao {
   public UserOracleDao() {
       System.out.println("正在创建UserOracleDao：" + this);
   }
}

@Service
public final class UserService {

   private IUserDao userDao;
   private IUserDao userOracleDao;
   @Autowired
   public void setUserDao(IUserDao userDao) {
       System.out.println("setUserDao：" + userDao);
       this.userDao = userDao;
   }
   @Autowired
   public void setUserOracleDao(IUserDao userOracleDao) {
       System.out.println("setUserOracleDao：" + userOracleDao);
       this.userOracleDao = userOracleDao;
   }
}