SpringBoot2.0 預設使用Lettuce作為Redis客戶端，在使用Lettuce時，需要額外引入commons-pool2包。建立一個SpringBoot2.x 專案之後，引入commons-pool2包。

    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-pool2</artifactId>
        <version>2.6.2</version>
    </dependency>
 

配置Redis和Lettuce

spring:
    host: 127.0.0.1
    port: 6380
    password: test
    timeout: 6000
    lettuce:
      pool:
        # 連線池最大連線數
        max-active: 64
        # 連線池最大空閒連線
        max-idle: 32
        # 連線池最小空閒連線
        min-idle: 16
        # 最大阻塞時間
        max-wait: 3000
    sentinel:
      master: master-redis
      nodes: 127.0.0.1:26379,127.0.0.1:26380,127.0.0.1:26381
 

Spring容器啟動時，由於spring-boot-autoconfigure包中spring.factories檔案中的配置，會自動裝配RedisAutoConfiguration類。
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration\

RedisAutoConfiguration類原始碼比較簡單，只是在自動注入時，先將Redis配置注入RedisProperties類，再例項化LettuceConnectionConfiguration類，最後在Miss RedisTemplate時建立兩個RedisTemplate例項。

@Configuration(
    proxyBeanMethods = false
)
//spring-boot-starter-redis中已引入
@ConditionalOnClass({RedisOperations.class})
//將配置注入Properties類
@EnableConfigurationProperties({RedisProperties.class})
//預設僅建立LettuceConnectionConfiguration Bean，Jedis缺少包
@Import({LettuceConnectionConfiguration.class, JedisConnectionConfiguration.class})
public class RedisAutoConfiguration {
    public RedisAutoConfiguration() {
    }

    @Bean
    @ConditionalOnMissingBean(
        name = {"redisTemplate"}
    )
    public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {
        RedisTemplate<Object, Object> template = new RedisTemplate();
        template.setConnectionFactory(redisConnectionFactory);
        return template;
    }

    @Bean
    @ConditionalOnMissingBean
    public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {
        StringRedisTemplate template = new StringRedisTemplate();
        template.setConnectionFactory(redisConnectionFactory);
        return template;
    }
}

在沒有自定義Redis連線池時，建立RedisConnectionFactory

	@Bean
	@ConditionalOnMissingBean(RedisConnectionFactory.class)
	LettuceConnectionFactory redisConnectionFactory(
			ObjectProvider<LettuceClientConfigurationBuilderCustomizer> builderCustomizers,
			ClientResources clientResources) throws UnknownHostException {
		LettuceClientConfiguration clientConfig = getLettuceClientConfiguration(builderCustomizers, clientResources,
				getProperties().getLettuce().getPool());
		return createLettuceConnectionFactory(clientConfig);
	}

LettuceClient裝配時，readFrom預設為空，若需要配置讀寫分離，則需要將其重寫設定為readFrom = REPLICA_PREFERRED，表明讀取從從庫中操作。

	private LettuceClientConfiguration getLettuceClientConfiguration(
			ObjectProvider<LettuceClientConfigurationBuilderCustomizer> builderCustomizers,
			ClientResources clientResources, Pool pool) {
		LettuceClientConfigurationBuilder builder = createBuilder(pool);
		applyProperties(builder);
		if (StringUtils.hasText(getProperties().getUrl())) {
			customizeConfigurationFromUrl(builder);
		}
		builder.clientOptions(initializeClientOptionsBuilder().timeoutOptions(TimeoutOptions.enabled()).build());
		builder.clientResources(clientResources);
		builderCustomizers.orderedStream().forEach((customizer) -> customizer.customize(builder));
		return builder.build();
	}

根據配置決定為Standalone、Sentinel、Cluster模式

	private LettuceConnectionFactory createLettuceConnectionFactory(LettuceClientConfiguration clientConfiguration) {
		if (getSentinelConfig() != null) {
			return new LettuceConnectionFactory(getSentinelConfig(), clientConfiguration);
		}
		if (getClusterConfiguration() != null) {
			return new LettuceConnectionFactory(getClusterConfiguration(), clientConfiguration);
		}
		return new LettuceConnectionFactory(getStandaloneConfig(), clientConfiguration);
	}

參考自：https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.0-Migration-Guide#redis