Solve Jackson 2 deserialization LocalDateTime error

Today, when integrating redis and spring boot, I encountered an error. Record it.

The error is reported as follows:

Could not read JSON: Cannot construct instance of `java.time.LocalDateTime` (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator)

After viewing, it is found that when the data is taken out of redis, Jackson 2 cannot process the LocalDateTime type by deserializing the data. The reason is that when Jackson 2 serializes the LocalDateTime, it is not in the normal time format, but in the format shown in the following figure

{
    "date": {
        "year": 2019,
        "month": "FEBRUARY",
        "day": 27,
        "dayOfMonth": 27,
        "dayOfWeek": "WEDNESDAY",
        "era": [
            "java.time.chrono.IsoEra",
            "CE"
        ],
        "dayOfYear": 58,
        "leapYear": false,
        "chronology": {
            "id": "ISO",
            "calendarType": "iso8601"
        },
        "prolepticMonth": 24229,
        "monthValue": 2
    },
    "time": {
        "hour": 12,
        "minute": 10,
        "second": 17,
        "nano": 0
    },
    "month": "FEBRUARY",
    "year": 2019,
    "dayOfMonth": 27,
    "dayOfWeek": "WEDNESDAY",
    "dayOfYear": 58,
    "hour": 12,
    "minute": 10,
    "nano": 0,
    "second": 17,
    "monthValue": 2,
    "chronology": [
        "java.time.chrono.IsoChronology",
        {
            "id": "ISO",
            "calendarType": "iso8601"
        }
    ]
}

 

Therefore, the serialization of LocalDateTime by Jackson 2 is not consistent with what we expected. Just modify the serialization template registered to redis as follows

 1 @Configuration
 2 public class RedisConfig {
 3 
 4     /**
 5      * Define UserRedisTemplate, specify the processing classes of serialization and deserialization
 6      *
 7      * @param factory redis Connection factory
 8      * @return Template
 9      */
10     @Bean("UserRedisTemplate")
11     public RedisTemplate<String, User> userRedisTemplate(RedisConnectionFactory factory) {
12         RedisTemplate<String, User> template = new RedisTemplate<>();
13         template.setConnectionFactory(factory);
14         Jackson2JsonRedisSerializer<User> j2jrs = new Jackson2JsonRedisSerializer<>(User.class);
15         ObjectMapper om = new ObjectMapper();
16         om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
17         // Solve the problem that jackson2 cannot deserialize LocalDateTime
18         om.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
19         om.registerModule(new JavaTimeModule());
20         om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL, JsonTypeInfo.As.PROPERTY);
21         j2jrs.setObjectMapper(om);
22         // serialize value Use this serialization method when
23         template.setValueSerializer(j2jrs);
24         template.setHashValueSerializer(j2jrs);
25         // serialize key Time
26         StringRedisSerializer srs = new StringRedisSerializer();
27         template.setKeySerializer(srs);
28         template.setHashKeySerializer(srs);
29         template.afterPropertiesSet();
30         return template;
31     }
32 }

Mainly the two sentences marked with red

 

Reference documents:

Deserialization of GenericJackson2JsonRedisSerializer

Tags: Java Redis Spring JSON

Posted on Mon, 02 Dec 2019 01:51:32 -0500 by daneth1712