redis集群搭建可参考：redis集群搭建-CSDN博客
一、简述
Redis（Remote Dictionary Server）是一个开源的、基于内存的高性能键值对存储系统，通常用作数据库、缓存和消息代理。它支持多种数据结构，包括字符串、哈希、列表、集合和有序集合
1.1 Redis相关问题
1、Redis是单线程模式，但速度很快，原因是：
1.Redis的数据存储在内存中，读写速度极快
2.Redis的单线程避免了多线程的上下文切换
3.采用I/O复用技术，可以同时处理多个请求
4.采用高效的数据结构，例如：哈希表
2、Redis序列化：
Redis的序列化作用是将对象转换为字节流以便存储或传输，在Redis中，所有数据都是以字节的形式存储的，因此当我们需要将对象存储到Redis时，需要先将其序列化为字节数组；
3、Redis序列化的形式：
StringRedisSerializer：将String类型的数据序列化为字节数组，适用于String或数值类型数据。
GenericJackson2JsonRedisSerializer：使用Jackson库将对象序列化为JSON字符串，这种方式适用于复杂的对象数据，因为它可以保留对象的结构和属性。
JdkSerializationRedisSerializer：使用Java内置的序列化机制，将对象转换为字节流。这是Redis的默认序列化方式
二、redis的使用
2.1 redis做数据库
1、添加依赖
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>2、配置连接
# application.yml
spring:redis:host: localhostport: 6379password: yourpassword3、创建配置类
@Configuration
public class RedisConfig {@Beanpublic RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {RedisTemplate<String, Object> template = new RedisTemplate<>();template.setConnectionFactory(redisConnectionFactory);// 使用StringRedisSerializer来序列化和反序列化redis的key值template.setKeySerializer(new StringRedisSerializer());// 使用GenericJackson2JsonRedisSerializer来序列化和反序列化redis的value值template.setValueSerializer(new GenericJackson2JsonRedisSerializer());// 设置hash key 和 value 序列化模式template.setHashKeySerializer(new StringRedisSerializer());template.setHashValueSerializer(new GenericJackson2JsonRedisSerializer());template.afterPropertiesSet();return template;}
}4、服务层和redis交互
@Service
public class RedisService {@Autowiredprivate RedisTemplate<String, Object> redisTemplate;public void setKey(String key, Object value) {redisTemplate.opsForValue().set(key, value);}public Object getKey(String key) {return redisTemplate.opsForValue().get(key);}//hashpublic void setHash(String key, Map<String, Object> values) {HashOperations<String, Object, Object> hashOperations = stringRedisTemplate.opsForHash();hashOperations.putAll(key, values);}public Map<Object, Object> getHash(String key) {HashOperations<String, Object, Object> hashOperations = stringRedisTemplate.opsForHash();return hashOperations.entries(key);}//参数是hash表的键名和字段名public Object getHashField(String key, String field) {HashOperations<String, Object, Object> hashOperations = stringRedisTemplate.opsForHash();return hashOperations.get(key, field);}//listpublic void leftPush(String key, String value) {ListOperations<String, String> listOperations = stringRedisTemplate.opsForList();listOperations.leftPush(key, value);}//key是键 start开始索引，从0开始 end结束索引，如果设为-1，表示获取列表中的所有元素public List<String> getRange(String key, long start, long end) {ListOperations<String, String> listOperations = stringRedisTemplate.opsForList();return listOperations.range(key, start, end);}//Zsetpublic void addZSetMember(String key, String value, double score) {ZSetOperations<String, String> zSetOperations = stringRedisTemplate.opsForZSet();zSetOperations.add(key, value, score);}public Set<String> getZSetMembers(String key) {ZSetOperations<String, String> zSetOperations = stringRedisTemplate.opsForZSet();return zSetOperations.range(key, 0, -1);}
}2.2 redis做缓存
1、添加完依赖后，在启动类添加注解@EnableCaching
@SpringBootApplication
@EnableCaching
public class YourApplication {public static void main(String[] args) {SpringApplication.run(YourApplication.class, args);}
}2、创建缓存的配置类
@Configuration
@EnableCaching
public class RedisConfig extends CachingConfigurerSupport {@Beanpublic RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {RedisTemplate<String, Object> template = new RedisTemplate<>();template.setConnectionFactory(factory);// 设置key和value的序列化器template.setKeySerializer(new StringRedisSerializer());template.setValueSerializer(new GenericJackson2JsonRedisSerializer());return template;}@Beanpublic CacheManager cacheManager(RedisConnectionFactory factory) {RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig().entryTtl(Duration.ofMinutes(10)) // 设置缓存过期时间.serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(new StringRedisSerializer())) // 设置key序列化方式.serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new GenericJackson2JsonRedisSerializer())); // 设置value序列化方式return RedisCacheManager.builder(factory).cacheDefaults(config).build();}
}3、定义mapper和xml文件中的sql
public interface UserMapper {User getUserById(Long id);
}//有多个参数时
public interface UserMapper {User getUserByIdAndName(@Param("id") Long id, @Param("name") String name);
}<!-- UserMapper.xml -->
<mapper namespace="com.example.mapper.UserMapper"><select id="getUserById" resultType="com.example.entity.User">SELECT * FROM user WHERE id = #{id}</select>
</mapper><!-- 多个参数时 -->
<select id="getUserByIdAndName" resultType="User">SELECT * FROM users WHERE id = #{id} AND name = #{name}
</select>4、service层添加缓存注解
@Service
public class UserService {@Autowiredprivate UserMapper userMapper;@Cacheable(value = "userCache", key = "#id")public User getUserById(Long id) {return userMapper.getUserById(id);}//多个参数时@Cacheable(value = "users", key = "#id + '_' + #name")public User getUserByIdAndName(Long id, String name) {return userMapper.getUserByIdAndName(id, name);}
}@Cacheable注解指定了缓存的名称为userCache，并使用用户的ID作为缓存的键。如果缓存中已经存在对应键的数据，则直接从缓存中获取，否则执行方法内的逻辑，并将结果存入缓存
2.3 redis做分布式锁
1、添加依赖
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>2、获取和释放锁的类
@Component
public class RedisLock {@Autowiredprivate StringRedisTemplate stringRedisTemplate;private static final String LOCK_PREFIX = "lock:";private static final long DEFAULT_EXPIRE_TIME = 30; // 锁默认过期时间，单位：秒/*** 尝试获取锁** @param key 锁的键* @param expireTime 锁的过期时间，单位：秒* @return 是否获取锁成功*/public boolean tryLock(String key, long expireTime) {String lockKey = LOCK_PREFIX + key;// 使用SETNX命令尝试获取锁//lockKey是键，"locked"是值，expireTime是过期时间，TimeUnit.SECONDS指定了过期时间的单位为秒Boolean success = stringRedisTemplate.opsForValue().setIfAbsent(lockKey, "locked", expireTime, TimeUnit.SECONDS);return success != null && success;}/*** 释放锁** @param key 锁的键*/public void unlock(String key) {String lockKey = LOCK_PREFIX + key;// 删除锁键来释放锁stringRedisTemplate.delete(lockKey);}
}3、使用
@Service
public class YourService {@Autowiredprivate RedisLock redisLock;public void someMethod() {//key值，可以是业务id，保证唯一性String lockKey = "someResource";boolean lockAcquired = redisLock.tryLock(lockKey, 30); // 尝试获取锁，过期时间30秒if (lockAcquired) {try {// 执行需要同步的代码} finally {// 确保在代码执行完毕后释放锁redisLock.unlock(lockKey);}} else {// 处理获取锁失败的情况，例如重试或返回错误消息}}
}
