用springboot将redis点赞数量同步到MySQL写出代码

A：

1. 首先需要添加Redis和MySQL的依赖

<!-- Redis依赖 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

<!-- MySQL依赖 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

2. 在application.properties（或application.yml）中配置Redis和MySQL的连接信息

# Redis配置
spring.redis.host=127.0.0.1
spring.redis.port=6379
spring.redis.password=your-redis-password

# MySQL配置
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/your-database-name?useUnicode=true&characterEncoding=utf-8&allowMultiQueries=true&useSSL=false&serverTimezone=Asia/Shanghai
spring.datasource.username=your-mysql-username
spring.datasource.password=your-mysql-password
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# JPA配置
spring.jpa.hibernate.ddl-auto=create-drop
spring.jpa.generate-ddl=true
spring.jpa.show-sql=true

3. 创建RedisService类，用于操作Redis

@Service
public class RedisService {
    @Autowired
    private RedisTemplate<String, Object> redisTemplate;
    
    // 增加点赞数量
    public void incrLikes(String key) {
        redisTemplate.opsForValue().increment(key);
    }
    
    // 减少点赞数量
    public void decrLikes(String key) {
        redisTemplate.opsForValue().decrement(key);
    }
    
    // 获取点赞数量
    public Integer getLikes(String key) {
        Object value = redisTemplate.opsForValue().get(key);
        if (value != null) {
            return Integer.valueOf(value.toString());
        }
        return null;
    }
}

4. 创建MySQL实体类LikeCount，用于将Redis中的点赞数量同步到MySQL

@Entity
@Table(name = "like_count")
public class LikeCount {
    @Id
    private Long id;
    
    @Column(name = "`key`")
    private String key;
    
    @Column(name = "value")
    private Integer value;

    // getter和setter方法
}

5. 创建LikeCountRepository接口，用于操作MySQL

@Repository
public interface LikeCountRepository extends JpaRepository<LikeCount, Long> {
    LikeCount findByKey(String key);
}

6. 在对应的Controller中，调用RedisService操作Redis，并将结果存储到MySQL

@RestController
@RequestMapping("/like")
public class LikeController {
    @Autowired
    private RedisService redisService;
    
    @Autowired
    private LikeCountRepository likeCountRepository;

    @PostMapping("/{id}")
    public void like(@PathVariable Long id) {
        String key = "like:" + id;
        redisService.incrLikes(key);
        Integer likes = redisService.getLikes(key);
        if (likes != null) {
            LikeCount likeCount = likeCountRepository.findByKey(key);
            if (likeCount == null) {
                likeCount = new LikeCount();
                likeCount.setId(id);
                likeCount.setKey(key);
            }
            likeCount.setValue(likes);
            likeCountRepository.save(likeCount);
        }
    }
}

以上就是将Redis中的点赞数量同步到MySQL的具体实现代码。