SSM框架实现登录功能 （后台）

<mapper namespace="User">
    <resultMap type="com.zy.music.pojo.User" id="userResult">
        <id property="userId" column="user_id"/>
        <result property="userName" column="user_name"/>
        <result property="userPwd" column="user_pwd"/>
    </resultMap>
    
    <!-- 登录注册 -->
    <!-- 根据用户名查询用户 -->
    <select id="queryUserByUserName" resultMap="userResult">
        select * from zy_user where user_name=#{userName} and user_status=1
    </select>
</mapper>

public interface IUserDao {
    /**
     * 根据用户名查询用户信息
     * @param userName
     * @return
     * @throws Exception
     */
    public User queryUserByUserName(String userName) throws Exception;
}

@Repository
public class UserDaoImpl implements IUserDao {

    @Autowired
    private SqlSession sqlSession;
    
    @Override
    public User queryUserByUserName(String userName) throws Exception {
        return sqlSession.selectOne("User.queryUserByUserName", userName);
    }
}

public interface IUserService {
    /**
     * 根据用户名查询用户信息
     * @param userName
     * @return
     * @throws Exception
     */
    public User queryUserByUserName(String userName) throws Exception;
}

@Service
public class UserServiceImpl implements IUserService {

    @Autowired
    private IUserDao userDao;
    
    @Override
    public User queryUserByUserName(String userName) throws Exception {
        return userDao.queryUserByUserName(userName);
    }
}

@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private IUserService userService;
    
    /*
     * 用户登录
     */
    @RequestMapping(value = "/login", produces = "application/json;charset=utf-8")
    private String login(@RequestParam(value = "userName", required = true) String userName, 
            @RequestParam(value = "userPwd", required = false) String userPwd) {
        Map<String, Object> rtnMap = new HashMap<String, Object>();
        try {
            User user = userService.queryUserByUserName(userName);
            if(null != user) {
                //用户存在
                if(userPwd.equals(user.getUserPwd())) {
                    rtnMap.put("rtnCode", "密码正确，登录成功！");
                    //密码正确
                } else {
                    rtnMap.put("rtnCode", "密码错误，登录失败！");
                    //密码错误
                }
            } else {
                rtnMap.put("rtnCode", "用户名不存在，登录失败！");
                //用户不存在
            }
        } catch (Exception e) {
            rtnMap.put("rtnCode", "程序异常");
            e.printStackTrace();
        }
        return JsonUtil.objToJson(rtnMap);
    }
}