如何在Jackson2JsonRedisSerializer中反序列化java.time.Instant

问题背景 #

使用Jackson2JsonRedisSerializer操作Redis时，Aircraft类中的Instant类型字段lastSeenTime反序列化失败，报错提示缺少JSR310模块，但已添加对应Maven依赖。

配置代码：

@Bean
public RedisOperations<String , Aircraft> redisOperations(RedisConnectionFactory factory){
    Jackson2JsonRedisSerializer<Aircraft> serializer = new Jackson2JsonRedisSerializer<Aircraft>(Aircraft.class);
    RedisTemplate<String, Aircraft> template = new RedisTemplate<>();
    template.setConnectionFactory(factory);
    template.setDefaultSerializer(serializer);
    template.setKeySerializer(new StringRedisSerializer());
    return template;
}

Aircraft字段定义：

@JsonProperty("last_seen_time")
private Instant lastSeenTime;

错误信息：

默认不支持Java 8日期/时间类型java.time.Instant：请添加模块"com.fasterxml.jackson.datatype:jackson-datatype-jsr310"以启用处理（引用链：com.example.chapter6.sburredis.Aircraft["last_seen_time"]）

已添加的Maven依赖：

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
    <version>2.14.1</version>
</dependency>

对应JSON数据：

{
  "aircraft": [
    {
      "id": 108,
      "callsign": "AMF4263",
      "squawk": "4136",
      "reg": "N49UC",
      "flightno": "",
      "route": "LAN-DFW",
      "type": "B190",
      "category": "A1",
      "altitude": 20000,
      "heading": 235,
      "speed": 248,
      "lat": 38.865905,
      "lon": -90.429382,
      "barometer": 0,
      "vert_rate": 0,
      "selected_altitude": 0,
      "polar_distance": 12.99378,
      "polar_bearing": 345.393951,
      "is_adsb": true,
      "is_on_ground": false,
      "last_seen_time": 1672576769,
      "pos_update_time": 1672576769,
      "bds40_seen_time": null
      }
  ]
}

解决方法 #

1. 手动配置ObjectMapper并注册JavaTimeModule #

Jackson2JsonRedisSerializer默认使用的ObjectMapper不会自动注册JSR310模块，需要手动配置：

@Bean
public RedisOperations<String, Aircraft> redisOperations(RedisConnectionFactory factory) {
    Jackson2JsonRedisSerializer<Aircraft> serializer = new Jackson2JsonRedisSerializer<>(Aircraft.class);
    
    ObjectMapper objectMapper = new ObjectMapper();
    // 注册Java 8时间模块
    objectMapper.registerModule(new JavaTimeModule());
    // 适配秒级时间戳：关闭纳秒级时间戳解析/序列化
    objectMapper.configure(DeserializationFeature.READ_DATE_TIMESTAMPS_AS_NANOSECONDS, false);
    objectMapper.configure(SerializationFeature.WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS, false);
    // 可选：如果需要序列化时输出ISO格式而非时间戳，可开启下面配置
    // objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
    
    serializer.setObjectMapper(objectMapper);
    
    RedisTemplate<String, Aircraft> template = new RedisTemplate<>();
    template.setConnectionFactory(factory);
    template.setDefaultSerializer(serializer);
    template.setKeySerializer(new StringRedisSerializer());
    return template;
}

2. 字段级注解配置（可选） #

如果不想全局配置，可在Instant字段上添加注解指定时间格式：

@JsonProperty("last_seen_time")
@JsonFormat(shape = JsonFormat.Shape.NUMBER, timezone = "UTC")
private Instant lastSeenTime;

核心原因 #

• Jackson的JavaTimeModule不会自动关联到Jackson2JsonRedisSerializer的ObjectMapper实例，必须手动注册。
• 你的JSON中时间戳是秒级，而Jackson默认处理Instant时按毫秒级解析，因此需要关闭READ_DATE_TIMESTAMPS_AS_NANOSECONDS配置，确保秒级时间戳能正确转换为Instant对象。

内容的提问来源于stack exchange，提问作者Hamza