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Redis获取缓存异常：java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to XXX

Redis 获取缓存异常：java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to XXX。

出现这种异常，我需要自定义 ObjectMapper，设置一些参数，而不是直接使用 Jackson2JsonRedisSerializer 类中黙认的 ObjectMapper，看源代码可以知道，Jackson2JsonRedisSerializer 中的 ObjectMapper 是直接使用 new ObjectMapper() 创建的，这样 ObjectMapper 会将 Redis 中的字符串反序列化为 java.util.LinkedHashMap 类型，导致后续 Spring 对其进行转换成报错。其实我们只要它返回 Object 类型就可以了。

使用以下方法，构建一个 Jackson2JsonRedisSerializer 对象，将其注入RedisCacheConfiguration即可。

 

 

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private Jackson2JsonRedisSerializer<Object> jackson2JsonRedisSerializer() {
        Jackson2JsonRedisSerializer<Object> jackson2JsonRedisSerializer =
                new Jackson2JsonRedisSerializer<>(Object.class);
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        objectMapper.configure(MapperFeature.USE_ANNOTATIONS, false);
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
        // 此项必须配置，否则会报java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to XXX
        objectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL, JsonTypeInfo.As.PROPERTY);
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        jackson2JsonRedisSerializer.setObjectMapper(objectMapper);
        return jackson2JsonRedisSerializer;
    }
 
    @Bean
    public RedisCacheManager redisCacheManager(RedisConnectionFactory connectionFactory){
        //初始化一个RedisCacheWriter输出流
        RedisCacheWriter redisCacheWriter = RedisCacheWriter.nonLockingRedisCacheWriter(connectionFactory);
        //采用Jackson2JsonRedisSerializer序列化机制
 
//        Jackson2JsonRedisSerializer<Object> serializer = new Jackson2JsonRedisSerializer<Object>(Object.class);
 
        //创建一个RedisSerializationContext.SerializationPair给定的适配器pair
        RedisSerializationContext.SerializationPair<Object> pair = RedisSerializationContext.SerializationPair.fromSerializer(jackson2JsonRedisSerializer());
        //创建CacheConfig
        RedisCacheConfiguration defaultCacheConfig = RedisCacheConfiguration.defaultCacheConfig().serializeValuesWith(pair);
 
        return new RedisCacheManager(redisCacheWriter, defaultCacheConfig);
 
 
    }