背景

前两天被面试到这个问题，最初回答的不是很合理，登录次数这方面记录还一直往数据库上面想，后来感觉在数据库中加一个登录日志表，来查询一段时间内用户登录的次数，现在看来，自己还是太年轻了，做个登录限制肯定是为了防止数据库高并发，加一个表来记录登录日志，这就把请求都打到数据库了，后来看了前辈们的解决方案，可以用Redis来实现，包括登录次数和账号锁定，我最开始在回答这个问题的时候只回答到了账号锁定用Redis做管理，前者登录次数回答的比较差劲，后来我也及时复盘了这次面试，就标题的内容做出基本实现

环境

Java8、MySQL8、Redis、IDEA，环境支持的同学可以参考这份代码实现以下

代码实现

0. 项目结构图（供参考）

1. 数据库中的表（供参考）

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;-- ----------------------------
-- Table structure for login_demo_user
-- ----------------------------
DROP TABLE IF EXISTS `login_demo_user`;
CREATE TABLE `login_demo_user`  (`id` bigint NOT NULL COMMENT '主键',`username` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '用户名',`password` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL COMMENT '密码',PRIMARY KEY (`id`, `username`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;-- ----------------------------
-- Records of login_demo_user
-- ----------------------------
INSERT INTO `login_demo_user` VALUES (1, 'hh', 'hh');SET FOREIGN_KEY_CHECKS = 1;

2. 依赖（pom.xml）

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.2.1.RELEASE</version><relativePath/></parent><groupId>com.openallzzz</groupId><artifactId>logindemo</artifactId><version>0.0.1-SNAPSHOT</version><properties><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.2.0</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>1.2.1</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.20</version></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build>
</project>

3. 配置文件（application.yml）

server:port: 8080spring:profiles:active: devmain:allow-circular-references: truedatasource:druid:driver-class-name: ${datasource.driver-class-name}url: jdbc:mysql://${datasource.host}:${datasource.port}/${datasource.database}?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowPublicKeyRetrieval=trueusername: ${datasource.username}password: ${datasource.password}redis:host: ${redis.host}port: ${redis.port}database: ${redis.database}mybatis:#mapper配置文件mapper-locations: classpath:mapper/*.xmltype-aliases-package: com.openallzzz.logindemo.entityconfiguration:#开启驼峰命名map-underscore-to-camel-case: truelogging:level:com:openallzzz:mapper: debugservice: infocontroller: info

4. 配置文件（application-dev.yml）

datasource:driver-class-name: com.mysql.cj.jdbc.Driverhost: localhostport: 3306database: testdbusername: rootpassword: root
redis:host: localhostport: 6379database: 1

5. UserLoginDTO

package com.openallzzz.logindemo.dto;import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;@Data
@AllArgsConstructor
@NoArgsConstructor
public class UserLoginDTO {private String username;private String password;}

6. DemoConstant

package com.openallzzz.logindemo.constant;public class DemoConstant {// 每分钟限制登录的最大次数public static final int MAX_LOGIN_TIMRS_PER_MINUTE = 5;
}

7. User（后来才用的lombok，没有统一写法）

package com.openallzzz.logindemo.entity;public class User {private Long id;private String username;private String password;public Long getId() {return id;}public void setId(Long id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}
}

8. UserMapper

package com.openallzzz.logindemo.mapper;import com.openallzzz.logindemo.entity.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;@Mapper
public interface UserMapper {@Select("select id, username, password from login_demo_user where username = #{username}")User selectByUsername(String username);}

9. UserService（供参考）

package com.openallzzz.logindemo.service;import com.openallzzz.logindemo.constant.DemoConstant;
import com.openallzzz.logindemo.dto.UserLoginDTO;
import com.openallzzz.logindemo.entity.User;
import com.openallzzz.logindemo.mapper.UserMapper;
import com.openallzzz.logindemo.result.Result;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;import java.util.concurrent.TimeUnit;@Service
@Slf4j
public class UserService {@Autowiredprivate UserMapper userMapper;@Autowiredprivate RedisTemplate redisTemplate;public Result<String> login(UserLoginDTO userLoginDTO) {if (userLoginDTO == null || userLoginDTO.getUsername() == null || userLoginDTO.getPassword() == null) {return Result.error("用户信息不完整！");}String username = userLoginDTO.getUsername();String password = userLoginDTO.getPassword();boolean lockStatus = getLockStatus(username);if (lockStatus) {return Result.error("失败次数过多，请稍后重试");}User user = userMapper.selectByUsername(username);if (user.getPassword().equals(password)) {clearLastCount(username);clearLockStatus(username);return Result.success();} else {int lastCount = getLastCount(username);if (lastCount + 1 == DemoConstant.MAX_LOGIN_TIMRS_PER_MINUTE) {setLockStatus(username);return Result.error("失败次数过多，请稍后重试");} else {setLastCount(username);return Result.error("登录失败，请检查用户名或密码，再重试");}}}private void clearLockStatus(String username) {log.info("清除用户锁定状态：{}", username);String key = "Lock" + ":" + username;redisTemplate.delete(key);}private void clearLastCount(String username) {log.info("将用户登录次数还原：{}", username);String key = "Count" + ":" + username;redisTemplate.delete(key);}private int getLastCount(String username) {log.info("获取用户一分钟内已经失败登录了多少次：{}", username);String key = "Count" + ":" + username;Integer count = (Integer) redisTemplate.opsForValue().get(key);return count == null ? 0 : count;}private void setLastCount(String username) {log.info("设置用户一分钟内已经失败登录了多少次：{}", username);String key = "Count" + ":" + username;redisTemplate.opsForValue().set(key, getLastCount(username) + 1, 1, TimeUnit.MINUTES);}private void setLockStatus(String username) {log.info("锁定用户，限制其登录：{}", username);String key = "Lock" + ":" + username;redisTemplate.opsForValue().set(key, "lock", 2, TimeUnit.HOURS);}private boolean getLockStatus(String username) {log.info("获取用户是否被限制其登录：{}", username);String key = "Lock" + ":" + username;String o = (String) redisTemplate.opsForValue().get(key);if ("lock".equals(o)) return true;return false;}}

10. UserController

package com.openallzzz.logindemo.controller;import com.openallzzz.logindemo.dto.UserLoginDTO;
import com.openallzzz.logindemo.result.Result;
import com.openallzzz.logindemo.service.UserService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
@RequestMapping("/user")
@Slf4j
public class UserController {@Autowiredprivate UserService userService;@PostMapping("/login")public Result<String> login(@RequestBody UserLoginDTO userLoginDTO) {log.info("用户登录：{}", userLoginDTO);return userService.login(userLoginDTO);}}

11. RedisConfig

package com.openallzzz.logindemo.config;import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;@Configuration
@EnableCaching
public class RedisConfig {@Bean(name = "redisTemplate")public RedisTemplate<String,Object> redisTemplate(RedisConnectionFactory factory){RedisTemplate<String,Object> template = new RedisTemplate<>();//配置连接工厂template.setConnectionFactory(factory);//使用jackson序列化和反序列value的值，Jackson2JsonRedisSerializer jacksonSerializer = new Jackson2JsonRedisSerializer(Object.class);ObjectMapper mapper = new ObjectMapper();//指定需要序列化的范围，All表示field、get和set，以及修饰符范围，ANY表示所有范围，包括privatemapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);jacksonSerializer.setObjectMapper(mapper);//设置template中value使用Jackson2JsonRedisSerializer序列化template.setValueSerializer(jacksonSerializer);//设置template中key使用StringRedisSerializer序列化template.setKeySerializer(new StringRedisSerializer());//这是hash中key和value的序列化方式,key采用StringRedisSerializer，value采用Jackson2JsonRedisSerializertemplate.setHashKeySerializer(new StringRedisSerializer());template.setHashValueSerializer(jacksonSerializer);//使template属性生效template.afterPropertiesSet();return template;}
}

12. 统一返回结果

package com.openallzzz.logindemo.result;import lombok.Data;import java.io.Serializable;/*** 后端统一返回结果* @param <T>*/
@Data
public class Result<T> implements Serializable {private Integer code; //编码：1成功，0和其它数字为失败private String msg; //错误信息private T data; //数据public static <T> Result<T> success() {Result<T> result = new Result<T>();result.code = 1;return result;}public static <T> Result<T> success(T object) {Result<T> result = new Result<T>();result.data = object;result.code = 1;return result;}public static <T> Result<T> error(String msg) {Result result = new Result();result.msg = msg;result.code = 0;return result;}}

13. 启动类LoginDemoApplication

package com.openallzzz.logindemo;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class LoginDemoApplication {public static void main(String[] args) {SpringApplication.run(LoginDemoApplication.class, args);}}

测试登录接口（一分钟内五次密码全错，触发账号锁定登录权限）

第一次测试（300ms）

第二次测试（32ms）

第三次测试（22ms）

第四次测试（12ms）

第五次测试（8ms）

总结

登录业务预先判断了该账号是否被锁定，如果短期内有大量登录请求（用户不断试错、被恶意攻击），压力只会给到Redis，从而避免DB被大量请求打中。