<dependency>
     <groupId>com.aliyun</groupId>
     <artifactId>aliyun-java-sdk-core</artifactId>
     <version>4.6.0</version>
 </dependency>
 <dependency>
      <groupId>com.aliyun</groupId>
      <artifactId>aliyun-java-sdk-dysmsapi</artifactId>
      <version>2.1.0</version>
 </dependency>

public class SMSUtils {
  /**
   * 发送短信
   * @param signName 签名
   * @param templateCode 模板
   * @param phoneNumbers 手机号
   * @param param 参数
   */
  public static void sendMessage(String signName, String templateCode,String phoneNumbers,String param){
    DefaultProfile profile = DefaultProfile.getProfile("cn-hangzhou", "", "");
    IAcsClient client = new DefaultAcsClient(profile);
    SendSmsRequest request = new SendSmsRequest();
    request.setSysRegionId("cn-hangzhou");
    request.setPhoneNumbers(phoneNumbers);
    request.setSignName(signName);
    request.setTemplateCode(templateCode);
    request.setTemplateParam("{\"code\":\""+param+"\"}");
    try {
      SendSmsResponse response = client.getAcsResponse(request);
      System.out.println("短信发送成功");
    }catch (ClientException e) {
      e.printStackTrace();
    } } }

public class ValidateCodeUtils {
    /**
     * 随机生成验证码
     * @param length 长度为4位或者6位
     * @return
     */
    public static Integer generateValidateCode(int length){
        Integer code =null;
        if(length == 4){
            code = new Random().nextInt(9999);//生成随机数，最大为9999
            if(code < 1000){
                code = code + 1000;//保证随机数为4位数字
            }
        }else if(length == 6){
            code = new Random().nextInt(999999);//生成随机数，最大为999999
            if(code < 100000){
                code = code + 100000;//保证随机数为6位数字
            }
        }else{
            throw new RuntimeException("只能生成4位或6位数字验证码");
        }
        return code;
    }
    /**
     * 随机生成指定长度字符串验证码
     * @param length 长度
     * @return
     */
    public static String generateValidateCode4String(int length){
        Random rdm = new Random();
        String hash1 = Integer.toHexString(rdm.nextInt());
        String capstr = hash1.substring(0, length);
        return capstr;
    } }

@RestController
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;
    @PostMapping("/sendMsg")
    public R<String> sendMsg(@RequestBody User user, HttpSession session) {
//获取手机号
        String phone = user.getPhone();
        if (StringUtils.isNotEmpty(phone)) {
//            生成随机的4位验证码
            String code = ValidateCodeUtils.generateValidateCode(4).toString();
//        调用阿里云提供的短信服务API完成发送短信
 SMSUtils.sendMessage("测试名字","",phone,code);      
//        将生成的验证码保存到Session
            session.setAttribute(phone, code);
            return R.success("手机验证码发送成功");
        }
        return R.error("短信发送失败");
    }
    @PostMapping("/login")
    public R<User> login(@RequestBody Map map, HttpSession session) {
//        获取手机号
        String phone = map.get("phone").toString();
//        获取验证码
        String code = map.get("code").toString();
//        从session中获取保存的验证码
        Object codeInSession = session.getAttribute(phone);
//        进行验证码的比对
        if (codeInSession != null && codeInSession.equals(code)) {
//            如果比对成功,说明登录成功
            LambdaQueryWrapper<User> queryWrapper = new LambdaQueryWrapper<>();
            queryWrapper.eq(User::getPhone, phone);
            User user = userService.getOne(queryWrapper);
            if (user == null) {
//            判断当前手机号对应的用户是否为新用户，如果是新用户就自动完成注册
                user = new User();
                user.setPhone(phone);
                user.setStatus(1);
                userService.save(user);
            }
            session.setAttribute("user", user.getId());
            return R.success(user);
        }
        return R.error("登录失败");
    } }