如何处理Long类型精度丢失问题

旧城等待， 2024-03-26 12:29 34阅读 0赞

## 问题原因 ##

> 当实体类字段为Long类型且值超过前端js显示的长度范围时会导致前端回显错误，解决方案也很简单，即在后端生成json之前将Long类型数据转成String类型。

### 解决方案如下 ###

1.  使用JsonSerialize注解序列化的时候把Long自动转为String（针对单个属性）

import lombok.Data;
    import lombok.ToString;
    mport com.fasterxml.jackson.databind.annotation.JsonSerialize;
    import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
    
    @Data
    @ToString(callSuper = true)
    public class AirOrderInfo {
        
        /**
         * 主区域id
         */
        @JsonSerialize(using = ToStringSerializer.class)
        private Long regionId;
        /**
         * 操作员id
         */
        @JsonSerialize(using = ToStringSerializer.class)
        private Long operId;
        /**
         * 订单名称
         */
        private String orderName;

1.  添加JacksonConfig配置全局序列化（针对所有属性）

package com.ruoyi.framework.config;
    
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
    import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
    import com.fasterxml.jackson.annotation.JsonInclude;
    import com.fasterxml.jackson.databind.MapperFeature;
    import com.fasterxml.jackson.databind.ObjectMapper;
    import com.fasterxml.jackson.databind.module.SimpleModule;
    import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
    
    /**
     1. Jackson配置
     */
    @Configuration
    public class JacksonConfig
    {
        
        @Bean
        public MappingJackson2HttpMessageConverter jackson2HttpMessageConverter()
        {
        
            final Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
            builder.serializationInclusion(JsonInclude.Include.NON_NULL);
            final ObjectMapper objectMapper = builder.build();
            SimpleModule simpleModule = new SimpleModule();
            // Long 转为 String 防止 js 丢失精度
            simpleModule.addSerializer(Long.class, ToStringSerializer.instance);
            objectMapper.registerModule(simpleModule);
            // 忽略 transient 关键词属性
            objectMapper.configure(MapperFeature.PROPAGATE_TRANSIENT_MARKER, true);
            // 时区设置
            objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));
            objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
            return new MappingJackson2HttpMessageConverter(objectMapper);
        }
    }

1.  添加JsonSerializerManage配置全局序列化（和方案2效果一样）

package com.xxx.config;
    
    import com.fasterxml.jackson.databind.ObjectMapper;
    import com.fasterxml.jackson.databind.module.SimpleModule;
    import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
    import org.springframework.boot.jackson.JsonComponent;
    import org.springframework.context.annotation.Bean;
    import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
    
    @JsonComponent
    public class JsonSerializerManage {
        
    
        @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);
    
            /**
             * 序列换成json时,将所有的long变成string
             * 因为js中得数字类型不能包含所有的java long值
             */
            SimpleModule module = new SimpleModule();
            module.addSerializer(Long.class, ToStringSerializer.instance);
            module.addSerializer(Long.TYPE, ToStringSerializer.instance);
            
            objectMapper.registerModule(module);
            return objectMapper;
        }
    }