ObjectMapper序列化轉換，日期時間戳互轉

案例：

import cn.hutool.core.date.DateUtil;
import cn.hutool.core.date.LocalDateTimeUtil;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import java.io.IOException;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneId;

/**
 * @author qhong
 * @date 2021/11/5 12:20
 **/
@Configuration
public class LocalDateTimeSerializerConfig {

    /**
     * 序列化LocalDateTime
     *
     * @return
     */
    @Bean
    @Primary
    public ObjectMapper serializingObjectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();

        // 通過該方法對mapper對象進行設置，所有序列化的對象都將按改規則進行系列化
        // Include.Include.ALWAYS 默認
        // Include.NON_DEFAULT 屬性爲默認值不序列化
        // Include.NON_EMPTY 屬性爲 空（""） 或者爲 NULL 都不序列化，則返回的json是沒有這個字段的。這樣對移動端會更省流量
        // Include.NON_NULL 屬性爲NULL 不序列化
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
        // 允許忽略多傳入的字段，直接忽略
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        // 允許出現特殊字符和轉義符
        objectMapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true);
        // 允許出現單引號
        objectMapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);

        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer());
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer());
        objectMapper.registerModule(javaTimeModule);
        return objectMapper;
    }

    /**
     * 序列化實現
     */
    public static class LocalDateTimeSerializer extends JsonSerializer<LocalDateTime> {
        @Override
        public void serialize(LocalDateTime value, JsonGenerator gen, SerializerProvider serializers)
                throws IOException {
            if (value != null) {
                long timestamp = value.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();
                gen.writeNumber(timestamp);
            }
        }
    }

    /**
     * 反序列化實現
     */
    public static class LocalDateTimeDeserializer extends JsonDeserializer<LocalDateTime> {
        @Override
        public LocalDateTime deserialize(JsonParser p, DeserializationContext deserializationContext)
                throws IOException {
            long timestamp = p.getValueAsLong();
            if (timestamp > 0) {
                return LocalDateTime.ofInstant(Instant.ofEpochMilli(timestamp), ZoneId.systemDefault());
            } else {
                //兼容字符串格式時間傳入
                String value = p.getValueAsString();
                return LocalDateTimeUtil.of(DateUtil.parse(value));
            }
        }
    }
}

參考：