Springboot 接入Redis後發現隔一段時間連線會超時 command timed out，看了網上很多文章，都說設定超時時間，但其實不管你設定多久都還是會超時，後面想想應該跟超時時間沒關係，感覺像是連線通道關閉了。
後來瞭解到，原來springboot2.x之後，預設使用的client是lettuce，而不是jedis了，關於二者的區別，大家可以自行百度，先貼錯誤資訊

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)

大概瞭解到是連線池的問題，lettuce的連線池會自動斷開，找了很多解決方案都沒用，最後還是使用jedis作為redis的client，解決了問題，只需要在pom.xml檔案中做如下配置即可

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
    <exclusions>
        <!-- 過濾lettuce，使用jedis作為redis客戶端 -->
        <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>