SpringBoot jackson 配置localDate、localDateTime日期序列化，反序列化

1、application.yaml

spring.mvc.converters.preferred-json-mapper: jackson
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@Configuration
public class JacksonConfig {

    @Bean
    public Jackson2ObjectMapperBuilderCustomizer customizer() {
        return b ->
            b.simpleDateFormat("yyyy-MM-dd HH:mm:ss")
            	// long类型转string， 前端处理Long类型，数值过大会丢失精度
                .serializerByType(Long.class, ToStringSerializer.instance)
                .serializerByType(Long.TYPE, ToStringSerializer.instance)
                .serializationInclusion(JsonInclude.Include.NON_NULL)
                //指定反序列化类型，也可以使用@JsonFormat(pattern = "yyyy-MM-dd")替代。主要是mvc接收日期时使用
                .deserializerByType(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")))
                .deserializerByType(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")))
                // 日期序列化，主要返回数据时使用
                .serializerByType(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")))
                .serializerByType(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
    }
}
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2、spring boot jackson自动注入流程

JacksonAutoConfiguration

使用我们自定义的 Jackson2ObjectMapperBuilderCustomizer
生成Jackson2ObjectMapperBuilder

根据Jackson2ObjectMapperBuilder生成ObjectMapper

JacksonHttpMessageConvertersConfiguration

springboot mvc默认使用的Jackson，
跟据ObjectMapper生成MappingJackson2HttpMessageConverter

HttpMessageConvertersAutoConfiguration

MappingJackson2HttpMessageConverter 生成HttpMessageConverters

WebMvcAutoConfigurationAdapter

WebMvcAutoConfigurationAdapter里面有

把生成的HttpMessageConverters自动配置到mvc

源码地址 https://github.com/googalAmbition/hello-spring-boot/tree/main/33-jackson

整合Gson：https://blog.csdn.net/qq_23934475/article/details/126796526