Redis服务器宕机时Spring Boot应用启动失败，如何正常运行？

当本地Redis服务器正常时，应用运行无异常，但Redis宕机时启动失败，抛出连接拒绝异常。以下是配置类代码片段：

@Configuration
@EnableCaching
public class RedisCacheConfig extends CachingConfigurerSupport {

    @Bean
    public LettuceConnectionFactory redisConnectionFactory() {
        return new LettuceConnectionFactory(new RedisStandaloneConfiguration(),
                LettuceClientConfiguration.builder()
                        .commandTimeout(Duration.ofMillis(1000))
                        .build());
    }

    @Bean
    public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory connectionFactory) {
        RedisTemplate<Object, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(connectionFactory);
        return template;
    }

    //Cache manager configurations follow here...
}

抛出的异常信息：

org.springframework.data.redis.RedisConnectionFailureException: Unable to connect to Redis; nested exception is io.lettuce.core.RedisConnectionException: Unable to connect to localhost:6379
at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory$ExceptionTranslatingConnectionProvider.translateException(LettuceConnectionFactory.java:1689)
at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory$ExceptionTranslatingConnectionProvider.getConnection(LettuceConnectionFactory.java:1597)
...
14 common frames omitted
Caused by: io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: no further information: localhost/127.0.0.1:6379
Caused by: java.net.ConnectException: Connection refused: no further information
at java.base/sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at java.base/sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:777)

需求：Redis宕机时应用能继续运行，等价于未启用缓存的状态。

1. 禁用启动时的Redis连接校验 #

默认Lettuce连接工厂会在启动时强制校验Redis连接，这是启动失败的核心原因。修改配置关闭该校验：

@Bean
public LettuceConnectionFactory redisConnectionFactory() {
    LettuceClientConfiguration clientConfig = LettuceClientConfiguration.builder()
            .commandTimeout(Duration.ofMillis(1000))
            .validateConnection(false) // 关键：关闭启动阶段的连接校验
            .build();
    return new LettuceConnectionFactory(new RedisStandaloneConfiguration(), clientConfig);
}

2. 自定义缓存异常处理器 #

关闭启动校验后，实际执行缓存操作时仍会抛出连接异常，需通过CacheErrorHandler捕获异常并忽略，让业务逻辑正常执行：

@Override
public CacheErrorHandler errorHandler() {
    return new CacheErrorHandler() {
        @Override
        public void handleCacheGetError(RuntimeException exception, Cache cache, Object key) {
            if (exception instanceof RedisConnectionFailureException) {
                return; // 忽略Redis连接异常，直接走业务逻辑
            }
            throw exception;
        }

        @Override
        public void handleCachePutError(RuntimeException exception, Cache cache, Object key, Object value) {
            if (exception instanceof RedisConnectionFailureException) {
                return;
            }
            throw exception;
        }

        @Override
        public void handleCacheEvictError(RuntimeException exception, Cache cache, Object key) {
            if (exception instanceof RedisConnectionFailureException) {
                return;
            }
            throw exception;
        }

        @Override
        public void handleCacheClearError(RuntimeException exception, Cache cache) {
            if (exception instanceof RedisConnectionFailureException) {
                return;
            }
            throw exception;
        }
    };
}

3. 优化缓存管理器配置（可选） #

结合RedisCacheManager的配置，确保缓存操作的序列化和默认行为符合预期，配合异常处理器实现无缝降级：

@Bean
public CacheManager cacheManager(RedisConnectionFactory connectionFactory) {
    RedisCacheConfiguration cacheConfig = RedisCacheConfiguration.defaultCacheConfig()
            .serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(new StringRedisSerializer()))
            .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new GenericJackson2JsonRedisSerializer()));

    return RedisCacheManager.builder(connectionFactory)
            .cacheDefaults(cacheConfig)
            .build();
}

内容的提问来源于stack exchange，提问作者Tudor Cheregi