使用mybatisplus的redis自定义缓存

MybatisPlus提供了自定义Redis缓存的功能，可以通过自定义Redis缓存实现数据的快速查询。

1. 引入Redis依赖

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

2. 自定义缓存

@Component
public class RedisCache implements Cache {

    private final RedisTemplate<Object, Object> redisTemplate;
    private final String cacheName;
    private final long ttl;

    public RedisCache(RedisTemplate<Object, Object> redisTemplate, String cacheName) {
        this.redisTemplate = redisTemplate;
        this.cacheName = cacheName;
        this.ttl = 60 * 5; //默认5分钟过期时间
    }

    public RedisCache(RedisTemplate<Object, Object> redisTemplate, String cacheName, long ttl) {
        this.redisTemplate = redisTemplate;
        this.cacheName = cacheName;
        this.ttl = ttl;
    }

    @Override
    public String getId() {
        return cacheName;
    }

    @Override
    public void putObject(Object key, Object value) {
        redisTemplate.opsForValue().set(key, value, ttl, TimeUnit.SECONDS);
    }

    @Override
    public Object getObject(Object key) {
        return redisTemplate.opsForValue().get(key);
    }

    @Override
    public Object removeObject(Object key) {
        redisTemplate.delete(key);
        return null;
    }

    @Override
    public void clear() {
        redisTemplate.delete(redisTemplate.keys("*" + cacheName + "*"));
    }

    @Override
    public int getSize() {
        return Math.toIntExact(redisTemplate.keys("*" + cacheName + "*").size());
    }

    @Override
    public ReadWriteLock getReadWriteLock() {
        return null;
    }
}

3. 注册自定义缓存

@Configuration
@EnableCaching
public class CacheConfig extends CachingConfigurerSupport {

    private final RedisConnectionFactory redisConnectionFactory;

    public CacheConfig(RedisConnectionFactory redisConnectionFactory) {
        this.redisConnectionFactory = redisConnectionFactory;
    }

    @Bean
    public CacheManager cacheManager() {
        RedisCacheConfiguration defaultCacheConfig = RedisCacheConfiguration.defaultCacheConfig()
                .entryTtl(Duration.ofMinutes(10))
                .disableCachingNullValues();

        RedisCacheConfiguration userCacheConfig = RedisCacheConfiguration.defaultCacheConfig()
                .entryTtl(Duration.ofMinutes(5))
                .disableCachingNullValues()
                .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new GenericJackson2JsonRedisSerializer()));

        Map<String, RedisCacheConfiguration> cacheConfigurations = new HashMap<String, RedisCacheConfiguration>() {{
            put("user", userCacheConfig);
        }};
        RedisCacheManager cacheManager = RedisCacheManager.builder(redisConnectionFactory)
                .cacheDefaults(defaultCacheConfig)
                .withInitialCacheConfigurations(cacheConfigurations)
                .build();

        return cacheManager;
    }

    @Bean
    @Override
    public CacheResolver cacheResolver() {
        return new SimpleCacheResolver(cacheManager());
    }

    @Bean
    @Override
    public CacheErrorHandler errorHandler() {
        return new SimpleCacheErrorHandler();
    }

    @Bean
    public Cache redisCache(RedisTemplate<Object, Object> redisTemplate) {
        return new RedisCache(redisTemplate, "product");
    }
}

4. 使用自定义缓存

在Mapper接口方法上添加@Cacheable注解，指定使用自定义的Redis缓存即可。

@Mapper
public interface UserMapper extends BaseMapper<User> {

    @Cacheable(value = "user", key = "#id")
    User getById(Long id);

}