How does Redis implement verification code sending and limit the number of daily sendings?

1. Function

• Enter your mobile phone number, click Send and a six-digit code will be randomly generated, valid for 2 minutes

• Enter the verification code , click verification, return success or failure

• Each mobile phone number can only be entered 3 times a day

2. Analysis

• Each mobile phone can only be entered 3 times a day: after each incr is sent, it is 1. When the value is 3, it prompts that it cannot be sent. The expiration time is the end of the day

• Randomly generate a 6-digit verification code: RandomUtil (hutool)

• The verification code is valid for 2 minutes: put it in redis and set the expiration time for 2 minutes

• Judge whether the verification code is consistent: get the verification code from redis and compare it with the entered verification code

3. Implementation

package cn.ken.blog.controller.common;

import cn.hutool.core.date.DateUnit;
import cn.hutool.core.date.DateUtil;
import cn.hutool.core.util.RandomUtil;
import cn.ken.blog.common.constant.Constants;
import cn.ken.blog.common.domain.Result;
import cn.ken.blog.common.enums.ErrorCodeEnum;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.util.ObjectUtils;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.Date;
import java.util.concurrent.TimeUnit;

/**
 * 验证码控制器
 * @author Ken-Chy129
 * @date 2022/4/17 20:28
 */
@RestController
@SuppressWarnings(value = { "unchecked", "rawtypes" })
public class CaptureController {
    
    @Autowired
    private RedisTemplate redisTemplate;
    
    // 生成验证码
    @GetMapping("getNumCode")
    public Result<String> getNumCode(String phone) {
        String captureLimitKey = Constants.CAPTCHA_LIMIT_KEY + phone;
        Integer counts = (Integer) redisTemplate.opsForValue().get(captureLimitKey);
        if (ObjectUtils.isEmpty(counts)) {
            // 今天第一次验证，故之前缓存中无该键
            // 距离今天结束剩下多少毫秒
            long expire = DateUtil.endOfDay(new Date()).between(new Date(), DateUnit.MS);
            redisTemplate.opsForValue().set(captureLimitKey, 1, expire, TimeUnit.MILLISECONDS);
        } else if (counts < 3) {
            // 没有超过限制次数
            redisTemplate.opsForValue().increment(captureLimitKey);
        } else {
            // 超过限制次数，不生成验证码，直接返回
            return new Result<String>().error(ErrorCodeEnum.OVER_LIMITS);
        }
        // 生成验证码
        String code = RandomUtil.randomNumbers(6); // 随机生成六位数
        String captureCodeKey = Constants.CAPTCHA_CODE_KEY + phone;
        redisTemplate.opsForValue().set(captureCodeKey, code, Constants.CAPTCHA_EXPIRATION, TimeUnit.MINUTES);
        return new Result<String>().success(captureCodeKey + ":" + code);
    }
    
    // 验证验证码
    @GetMapping("verify")
    public Result<String> verify(String phone, String code) {
        String captureCodeKey = Constants.CAPTCHA_CODE_KEY + phone;
        String realCode = (String) redisTemplate.opsForValue().get(captureCodeKey);
        if (ObjectUtils.isEmpty(realCode)) {
            // redis中不存在该用户生成的验证码，证明验证码以过期销毁
            return new Result<String>().error(ErrorCodeEnum.OVERDUE_CODE);
        }
        if (realCode.equals(code)) {
            return new Result<String>().success("验证成功");
        } else {
            return new Result<String>().error(ErrorCodeEnum.ERROR_CODE);
        }
    }
    
//    @Scheduled(cron = "0 0 12 * * ?")
//    private void clear() {
//        redisTemplate.delete()
//    }
}

// Constants类

/**
 * 验证码 redis key
 */
public static final String CAPTCHA_CODE_KEY = "captcha_codes:";

/**
 * 每日限制 redis key
 */
public static final String CAPTCHA_LIMIT_KEY = "captcha_limits:";
/**
 * 验证码有效期（分钟）
 */
public static final Integer CAPTCHA_EXPIRATION = 2;

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