后端的Long数据在转成json字符串返回给前端的时候，会有精度损失。

此时在我们的后端可以在Long类型的代码加入以下数据：

但是这些太过于麻烦，可以模仿字符串与localdatetime的转化(统一的配置)，写一个配置类，(建议在base过程写）代码如下

package com.xuecheng.base.config;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
@Configuration
public class LocalDateTimeConfig {
    /*
     * 序列化内容
     *   LocalDateTime -> String
     * 服务端返回给客户端内容
     * */
    @Bean
    public LocalDateTimeSerializer localDateTimeSerializer() {
        return new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
    }
    /*
     * 反序列化内容
     *   String -> LocalDateTime
     * 客户端传入服务端数据
     * */
    @Bean
    public LocalDateTimeDeserializer localDateTimeDeserializer() {
        return new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
    }
    //long转string避免精度损失
    @Bean
    public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
        ObjectMapper objectMapper = builder.createXmlMapper(false).build();
        //忽略value为null 时 key的输出
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        SimpleModule module = new SimpleModule();
        module.addSerializer(Long.class, ToStringSerializer.instance);
        module.addSerializer(Long.TYPE, ToStringSerializer.instance);
        objectMapper.registerModule(module);
        return objectMapper;
    }
    // 配置
    @Bean
    public Jackson2ObjectMapperBuilderCustomizer jackson2ObjectMapperBuilderCustomizer() {
        return builder -> {
            builder.serializerByType(LocalDateTime.class, localDateTimeSerializer());
            builder.deserializerByType(LocalDateTime.class, localDateTimeDeserializer());
        };
    }
}