uniapp项目微信授权登录，用vue3语言uni-ui组件，后端用springbootCloud分为controller层，service接口，service实现类，mapper接口和mapper配置文件，请写出符合的前后端代码

前端代码：

1. 登录页面的视图组件：

<template>
  <view>
    <button @click="login">微信授权登录</button>
  </view>
</template>

<script>
import { onMounted, ref } from "vue";
import { login } from "@/api/user";

export default {
  setup() {
    const loading = ref(false);

    const login = async () => {
      loading.value = true;
      try {
        const res = await uni.login();
        const code = res.code;
        const userInfo = await uni.getUserInfo();
        const data = {
          code,
          encryptedData: userInfo.encryptedData,
          iv: userInfo.iv,
        };
        await login(data);
        uni.switchTab({
          url: "/pages/index/index",
        });
      } catch (error) {
        console.error(error);
      } finally {
        loading.value = false;
      }
    };

    onMounted(() => {
      uni.showNavigationBarLoading();
    });

    return {
      loading,
      login,
    };
  },
};
</script>

2. 调用后端接口的 API：

import axios from "axios";

const BASE_URL = "http://localhost:8080";

export const login = async (data) => {
  return axios.post(`${BASE_URL}/api/user/login`, data);
};

后端代码：

1. Controller 层：

@RestController
@RequestMapping("/api/user")
public class UserController {
    @Autowired
    private UserService userService;

    @PostMapping("/login")
    public Result login(@RequestBody LoginDTO loginDTO) {
        return Result.success(userService.login(loginDTO));
    }
}

2. Service 接口：

public interface UserService {
    UserDTO login(LoginDTO loginDTO);
}

3. Service 实现类：

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;

    @Override
    public UserDTO login(LoginDTO loginDTO) {
        // TODO: 根据微信授权登录获取的 code、encryptedData 和 iv，调用微信 API 获取用户的 openid 和 session_key
        String openid = "mock openid";
        String sessionKey = "mock session_key";

        User user = userMapper.selectByOpenid(openid);
        if (user == null) {
            // 用户不存在，创建新用户
            user = new User();
            user.setOpenid(openid);
            user.setNickname(loginDTO.getNickname());
            user.setAvatarUrl(loginDTO.getAvatarUrl());
            userMapper.insert(user);
        } else {
            // 更新用户信息
            user.setNickname(loginDTO.getNickname());
            user.setAvatarUrl(loginDTO.getAvatarUrl());
            userMapper.updateByPrimaryKey(user);
        }

        UserDTO userDTO = new UserDTO();
        BeanUtils.copyProperties(user, userDTO);
        userDTO.setSessionKey(sessionKey);
        return userDTO;
    }
}

4. Mapper 接口和 Mapper 配置文件：

@Mapper
public interface UserMapper {
    int deleteByPrimaryKey(Integer id);

    int insert(User record);

    int insertSelective(User record);

    User selectByPrimaryKey(Integer id);

    int updateByPrimaryKeySelective(User record);

    int updateByPrimaryKey(User record);

    User selectByOpenid(String openid);
}

<mapper namespace="com.example.demo.mapper.UserMapper">

    <resultMap id="BaseResultMap" type="com.example.demo.domain.User">
        <id column="id" jdbcType="INTEGER" property="id"/>
        <result column="openid" jdbcType="VARCHAR" property="openid"/>
        <result column="nickname" jdbcType="VARCHAR" property="nickname"/>
        <result column="avatar_url" jdbcType="VARCHAR" property="avatarUrl"/>
    </resultMap>

    <insert id="insert" parameterType="com.example.demo.domain.User">
        insert into user (openid, nickname, avatar_url)
        values (#{openid,jdbcType=VARCHAR}, #{nickname,jdbcType=VARCHAR}, #{avatarUrl,jdbcType=VARCHAR})
    </insert>

    <select id="selectByOpenid" parameterType="String" resultMap="BaseResultMap">
        select *
        from user
        where openid = #{openid,jdbcType=VARCHAR}
    </select>

    <update id="updateByPrimaryKey" parameterType="com.example.demo.domain.User">
        update user
        set openid = #{openid,jdbcType=VARCHAR},
            nickname = #{nickname,jdbcType=VARCHAR},
            avatar_url = #{avatarUrl,jdbcType=VARCHAR}
        where id = #{id,jdbcType=INTEGER}
    </update>
</mapper>