JavaScript在处理long型数据时丢失精度问题

我就是我 2023-10-09 16:04 27阅读 0赞

## 项目场景： ##

员工后台管理系统

![1f7cb4640d2445a4bd4cc2d9e24da93f.png][]

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## 问题描述 ##

> 数据库更新失败

前端点击禁用后，显示修改成功

![8ab4b3cddaae4a8d9cea69fa04136452.png][]

![13c55aeae6714aeaac1780e9c4827714.png][]

但实际数据未被修改

![0e72f57bb649448bb35c0e436e3a006b.png][]

查看后端发现sql语句返回，更新了0条数据

SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@36dca314] was not registered for synchronization because synchronization is not active
    JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@6ff35b75] will not be managed by Spring
    ==>  Preparing: UPDATE employee SET status=?, update_time=?, update_user=? WHERE id=?
    ==> Parameters: 0(Integer), 2023-03-19T23:33:51.947594300(LocalDateTime), 1(Long), 1637477478634987500(Long)
    <==    Updates: 0

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## 原因分析： ##

> JavaScript在处理long型数据时丢失精度问题

![df10ac067f7e4afd9681e9b36f923c23.png][]

前端向后端发送id时，后端接收到的id与实际id后三位不符，说明JavaScript在处理long型数据时，可能会发生丢失精度的情况

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## 解决方案： ##

> 使用JacksonObjectMapper消息转换器，替换Spring框架默认的消息转换器

将JacksonObjectMapper复制进项目

package com.raggie.common;
    
    import com.fasterxml.jackson.databind.DeserializationFeature;
    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.LocalDateDeserializer;
    import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
    import com.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;
    import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;
    import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
    import com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;
    import java.math.BigInteger;
    import java.time.LocalDate;
    import java.time.LocalDateTime;
    import java.time.LocalTime;
    import java.time.format.DateTimeFormatter;
    import static com.fasterxml.jackson.databind.DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES;
    
    /**
     * 对象映射器:基于jackson将Java对象转为json，或者将json转为Java对象
     * 将JSON解析为Java对象的过程称为 [从JSON反序列化Java对象]
     * 从Java对象生成JSON的过程称为 [序列化Java对象到JSON]
     */
    public class JacksonObjectMapper extends ObjectMapper {
    
        public static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
        public static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";
        public static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";
    
        public JacksonObjectMapper() {
            super();
            //收到未知属性时不报异常
            this.configure(FAIL_ON_UNKNOWN_PROPERTIES, false);
    
            //反序列化时，属性不存在的兼容处理
            this.getDeserializationConfig().withoutFeatures(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
    
    
            SimpleModule simpleModule = new SimpleModule()
                    .addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)))
                    .addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)))
                    .addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)))
    
                    .addSerializer(BigInteger.class, ToStringSerializer.instance)
                    .addSerializer(Long.class, ToStringSerializer.instance)
                    .addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)))
                    .addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)))
                    .addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
    
            //注册功能模块 例如，可以添加自定义序列化器和反序列化器
            this.registerModule(simpleModule);
        }
    }

在配置类中添加消息转换器

@Override
        protected void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
            //创建消息转换器对象
            MappingJackson2HttpMessageConverter messageConverter = new MappingJackson2HttpMessageConverter();
            messageConverter.setObjectMapper(new JacksonObjectMapper());
            converters.add(0,messageConverter);
        }

重新运行程序，修改成功

![47f807c6b9534ab49846903635af6610.png][]

[1f7cb4640d2445a4bd4cc2d9e24da93f.png]: https://img-blog.csdnimg.cn/1f7cb4640d2445a4bd4cc2d9e24da93f.png
[8ab4b3cddaae4a8d9cea69fa04136452.png]: https://img-blog.csdnimg.cn/8ab4b3cddaae4a8d9cea69fa04136452.png
[13c55aeae6714aeaac1780e9c4827714.png]: https://img-blog.csdnimg.cn/13c55aeae6714aeaac1780e9c4827714.png
[0e72f57bb649448bb35c0e436e3a006b.png]: https://img-blog.csdnimg.cn/0e72f57bb649448bb35c0e436e3a006b.png
[df10ac067f7e4afd9681e9b36f923c23.png]: https://img-blog.csdnimg.cn/df10ac067f7e4afd9681e9b36f923c23.png
[47f807c6b9534ab49846903635af6610.png]: https://img-blog.csdnimg.cn/47f807c6b9534ab49846903635af6610.png