Springboot 接入Redis后发现隔一段时间连接会超时 command timed out，看了网上很多文章，都说设置超时时间，但其实不管你设置多久都还是会超时，后面想想应该跟超时时间没关系，感觉像是连接通道关闭了。
后来了解到，原来springboot2.x之后，默认使用的client是lettuce，而不是jedis了，关于二者的区别，大家可以自行百度，先贴错误信息

org.springframework.dao.QueryTimeoutException: Redis command timed out; nested exception is io.lettuce.core.RedisCommandTimeoutException: Command timed
 out after 5 second(s)
    at org.springframework.data.redis.connection.lettuce.LettuceExceptionConverter.convert(LettuceExceptionConverter.java:70)
    at org.springframework.data.redis.connection.lettuce.LettuceExceptionConverter.convert(LettuceExceptionConverter.java:41)
    at org.springframework.data.redis.PassThroughExceptionTranslationStrategy.translate(PassThroughExceptionTranslationStrategy.java:44)
    at org.springframework.data.redis.FallbackExceptionTranslationStrategy.translate(FallbackExceptionTranslationStrategy.java:42)
    at org.springframework.data.redis.connection.lettuce.LettuceConnection.convertLettuceAccessException(LettuceConnection.java:273)
    at org.springframework.data.redis.connection.lettuce.LettuceStringCommands.convertLettuceAccessException(LettuceStringCommands.java:799)
    at org.springframework.data.redis.connection.lettuce.LettuceStringCommands.get(LettuceStringCommands.java:68)
    at org.springframework.data.redis.connection.DefaultedRedisConnection.get(DefaultedRedisConnection.java:266)
    at org.springframework.data.redis.core.DefaultValueOperations$1.inRedis(DefaultValueOperations.java:57)
    at org.springframework.data.redis.core.AbstractOperations$ValueDeserializingRedisCallback.doInRedis(AbstractOperations.java:60)
    at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:228)
    at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:188)
    at org.springframework.data.redis.core.AbstractOperations.execute(AbstractOperations.java:96)
    at org.springframework.data.redis.core.DefaultValueOperations.get(DefaultValueOperations.java:53)

大概了解到是连接池的问题，lettuce的连接池会自动断开，找了很多解决方案都没用，最后还是使用jedis作为redis的client，解决了问题，只需要在pom.xml文件中做如下配置即可

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
    <exclusions>
        <!-- 过滤lettuce，使用jedis作为redis客户端 -->
        <exclusion>
            <groupId>io.lettuce</groupId>
            <artifactId>lettuce-core</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>redis.clients</groupId>
    <artifactId>jedis</artifactId>
</dependency>
<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-pool2</artifactId>
</dependency>