jedis 保存数字value ERR value is not an integer or out of ra

小咪咪 2022-05-25 07:40 240阅读 0赞

https://blog.csdn.net/wangjun5159/article/details/52387782

# 背景 #

使用spring redis的increment方法时，爆出如上错误，详细异常栈如下

> org.springframework.dao.InvalidDataAccessApiUsageException: ERR value is not an integer or out of range; nested exception is redis.clients.jedis.exceptions.JedisDataException: ERR value is not an integer or out of range   
> at org.springframework.data.redis.connection.jedis.JedisExceptionConverter.convert(JedisExceptionConverter.java:64)   
> at org.springframework.data.redis.connection.jedis.JedisExceptionConverter.convert(JedisExceptionConverter.java:41)   
> at org.springframework.data.redis.PassThroughExceptionTranslationStrategy.translate(PassThroughExceptionTranslationStrategy.java:37)   
> at org.springframework.data.redis.FallbackExceptionTranslationStrategy.translate(FallbackExceptionTranslationStrategy.java:37)   
> at org.springframework.data.redis.connection.jedis.JedisConnection.convertJedisAccessException(JedisConnection.java:212)   
> at org.springframework.data.redis.connection.jedis.JedisConnection.incrBy(JedisConnection.java:1439)   
> at org.springframework.data.redis.core.DefaultValueOperations$3.doInRedis(DefaultValueOperations.java:66)   
> at org.springframework.data.redis.core.DefaultValueOperations$3.doInRedis(DefaultValueOperations.java:63)   
> at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:202)   
> at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:164)   
> at org.springframework.data.redis.core.AbstractOperations.execute(AbstractOperations.java:88)   
> at org.springframework.data.redis.core.DefaultValueOperations.increment(DefaultValueOperations.java:63)

# 分析 #

redis对任何不合法的值，都称为ERR。   
![这里写图片描述][20160831193737636]   
也就是说，上述异常的意思是，增加的值（ERR）不是integer或者超出了integer范围，所以才报的错误。   
根据同事的建议，只有使用StringRedisSerializer序列化器才能使用incrment方法！那么为什么呢，为什么使用了StringRedisSerializer就可以而使用默认序列化器就不行呢？

# 实验 #

我们都知道序列化器是，将key或者value序列化成流，存储到redis。首先看一下RedisSerializer接口   
![这里写图片描述][20160831181505049]

它有两个方法，存储到redis时，使用的是serialize(T t)方法   
为了测试各个序列化器的区别，我做了个测试

@Test
        public void testSerializer(){
    
            RedisTemplate<String, String> template = new RedisTemplate<String, String>();
            template.setConnectionFactory(connectFactory);
            template.afterPropertiesSet();
    
            ValueOperations<String, String>  operations = template.opsForValue();
            template.setKeySerializer(new StringRedisSerializer());
            template.setValueSerializer(new StringRedisSerializer());
            operations.set("StringRedisSerializer", "1");
    
            template.setKeySerializer(new GenericToStringSerializer<String>(String.class));
            template.setValueSerializer(new GenericToStringSerializer<String>(String.class));
            operations.set("GenericToStringSerializer", "1");
    
    
            template.setKeySerializer(new GenericJackson2JsonRedisSerializer());
            template.setValueSerializer(new GenericJackson2JsonRedisSerializer());
            operations.set("GenericJackson2JsonRedisSerializer", "1");
    
            template.setKeySerializer(new Jackson2JsonRedisSerializer<String>(String.class));
            template.setValueSerializer(new Jackson2JsonRedisSerializer<String>(String.class));
            operations.set("Jackson2JsonRedisSerializer", "1");
    
            template.setKeySerializer(new JdkSerializationRedisSerializer());
            template.setValueSerializer(new JdkSerializationRedisSerializer());
            operations.set("JdkSerializationRedisSerializer", "1");
    
    
        }

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结果   
![这里写图片描述][20160831181924941]  
![这里写图片描述][20160831181933019]  
![这里写图片描述][20160831181942207]  
![这里写图片描述][20160831181949160]  
![这里写图片描述][20160831181956066]

# 领悟 #

至此真相大白，

*  GenericJackson2JsonRedisSerializer、Jackson2JsonRedisSerializer是先将对象转为json，然后再保存到redis，所以，1在redis中是字符串1，所以无法进行加1
 *  JdkSerializationRedisSerializer使用的jdk对象序列化，序列化后的值有类信息、版本号等，所以是一个包含很多字母的字符串，所以根本无法加1,这个序列化器跟memcache的序列化规则很像[memcache怎样存储的对象][memcache]
 *  GenericToStringSerializer、StringRedisSerializer将字符串的值直接转为字节数组，所以保存到redis中是数字，所以可以进行加1

最后，看一下StringRedisSerializer的源代码   
![这里写图片描述][20160831182812073]

GenericToStringSerializer serialize方法

public byte[] serialize(T object) {
            if (object == null) {
                return null;
            }
            String string = converter.convert(object, String.class);
            return string.getBytes(charset);
        }

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# 结论 #

使用GenericToStringSerializer、StringRedisSerializer序列化器，都可以使用increment方法

[20160831193737636]: /images/20220525/86401f42e05a40009979c0aeb5ea09fb.png
[20160831181505049]: /images/20220525/d4a632558c254759a1f3660f338db88b.png
[20160831181924941]: /images/20220525/562c5bb306804d2fb3226316771461d8.png
[20160831181933019]: /images/20220525/3dfcccd70f7b4e3ea814d553fdbc0b3f.png
[20160831181942207]: /images/20220525/504d8a889ae144e89b717bfb9bab0aa2.png
[20160831181949160]: /images/20220525/e8d13d0785af4d2c8d57bc055a86b5c5.png
[20160831181956066]: /images/20220525/46a3ca404fa146e7a2daca66f21782b7.png
[memcache]: http://blog.csdn.net/wangjun5159/article/details/51328899
[20160831182812073]: /images/20220525/a5367abfc9e34f41935268920abe4ef6.png