Springboot2.x集成lettuce连接redis集群报超时异常Command timed out after 6 second(s)

  1 //LettuceConnectionConfiguration
  2 @ConditionalOnClass({RedisClient.class})
  3 class LettuceConnectionConfiguration extends RedisConnectionConfiguration {
  4    ......省略
  5     @Bean
  6     @ConditionalOnMissingBean({RedisConnectionFactory.class})
  7     LettuceConnectionFactory redisConnectionFactory(ObjectProvider<LettuceClientConfigurationBuilderCustomizer> builderCustomizers, ClientResources clientResources) throws UnknownHostException {
  8         LettuceClientConfiguration clientConfig = this.getLettuceClientConfiguration(builderCustomizers, clientResources, this.getProperties().getLettuce().getPool());
  9         return this.createLettuceConnectionFactory(clientConfig);
 10    }
 11 }
 12 //JedisConnectionConfiguration
 13 @ConditionalOnClass({GenericObjectPool.class, JedisConnection.class, Jedis.class})
 14 class JedisConnectionConfiguration extends RedisConnectionConfiguration {
 15    ......省略
 16     @Bean
 17     @ConditionalOnMissingBean({RedisConnectionFactory.class})
 18     JedisConnectionFactory redisConnectionFactory(ObjectProvider<JedisClientConfigurationBuilderCustomizer> builderCustomizers) throws UnknownHostException {
 19         return this.createJedisConnectionFactory(builderCustomizers);
 20    }
 21 }
 22 

可见，LettuceConnectionConfiguration.class与JedisConnectionConfiguration.class当中都有一个相同的注解 @ConditionalOnMissingBean({RedisConnectionFactory.class})，这是说，假如RedisConnectionFactory这个bean已经被注册到容器里，那么与它相似的其他Bean就不会再被加载注册，简单点说，对LettuceConnectionConfiguration与JedisConnectionConfiguration各自加上 @ConditionalOnMissingBean({RedisConnectionFactory.class})注解，两者当中只能加载注册其中一个到容器里，另外一个就不会再进行加载注册。

那么，问题就来了，谁会先被注册呢？

这就回到了上面提到的一句，@Import({LettuceConnectionConfiguration.class, JedisConnectionConfiguration.class})这一句里的先后顺序很关键，LettuceConnectionConfiguration在前面，就意味着，LettuceConnectionConfiguration将会被注册。

可见，Springboot默认是使用lettuce来连接redis的。

当我们引入spring-boot-starter-data-redis依赖包时，其实就相当于引入lettuce包，这时就会使用lettuce驱动，若不想使用该默认的lettuce驱动，直接将lettuce依赖排除即可。

  1 <dependency>
  2     <groupId>org.springframework.boot</groupId>
  3     <artifactId>spring-boot-starter-data-redis</artifactId>
  4     <exclusions>
  5         <exclusion>
  6             <groupId>io.lettuce</groupId>
  7             <artifactId>lettuce-core</artifactId>
  8         </exclusion>
  9     </exclusions>
 10 </dependency>

  1 <dependency>
  2     <groupId>redis.clients</groupId>
  3     <artifactId>jedis</artifactId>
  4 </dependency>

  1 public Boolean zAdd(byte[] key, double score, byte[] value) {
  2     Assert.notNull(key, "Key must not be null!");
  3     Assert.notNull(value, "Value must not be null!");
  4 ​
  5     try {
  6         if (this.isPipelined()) {
  7             this.pipeline(this.connection.newLettuceResult(this.getAsyncConnection().zadd(key, score, value), LettuceConverters.longToBoolean()));
  8             return null;
  9        } else if (this.isQueueing()) {
 10             this.transaction(this.connection.newLettuceResult(this.getAsyncConnection().zadd(key, score, value), LettuceConverters.longToBoolean()));
 11             return null;
 12        } else {
 13             return LettuceConverters.toBoolean(this.getConnection().zadd(key, score, value));
 14        }
 15    } catch (Exception var6) {
 16         throw this.convertLettuceAccessException(var6);
 17    }
 18 }