配置SpringMvc全局序列化与反序列化，解决Long类型下精度丢失问题（使用FastJson2）

注意：方式一与方式二不可共同设置

方式一、使用Jackson解决Long类型在反序列化过程中精度丢失

SpringBoot添加配置文件

@Configuration
public class JacksonConfig {

    @Bean
    public Jackson2ObjectMapperBuilderCustomizer customizer() {
        return builder -> {
            // 全局配置序列化返回 JSON 处理
            JavaTimeModule javaTimeModule = new JavaTimeModule();
            javaTimeModule.addSerializer(Long.class, BigNumberSerializer.INSTANCE);
            javaTimeModule.addSerializer(Long.TYPE, BigNumberSerializer.INSTANCE);
            javaTimeModule.addSerializer(BigInteger.class, BigNumberSerializer.INSTANCE);
            javaTimeModule.addSerializer(BigDecimal.class, ToStringSerializer.instance);
            DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
            javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(formatter));
            javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(formatter));
            builder.modules(javaTimeModule);
            builder.timeZone(TimeZone.getDefault());
        };
    }

    @JacksonStdImpl
    static class BigNumberSerializer extends NumberSerializer {

        /**
         * 根据 JS Number.MAX_SAFE_INTEGER 与 Number.MIN_SAFE_INTEGER 得来
         */
        private static final long MAX_SAFE_INTEGER = 9007199254740991L;
        private static final long MIN_SAFE_INTEGER = -9007199254740991L;

        /**
         * 提供实例
         */
        public static final BigNumberSerializer INSTANCE = new BigNumberSerializer(Number.class);

        public BigNumberSerializer(Class<? extends Number> rawType) {
            super(rawType);
        }

        @Override
        public void serialize(Number value, JsonGenerator gen, SerializerProvider provider) throws IOException {
            // 超出范围 序列化位字符串
            if (value.longValue() > MIN_SAFE_INTEGER && value.longValue() < MAX_SAFE_INTEGER) {
                super.serialize(value, gen, provider);
            } else {
                gen.writeString(value.toString());
            }
        }
    }

}

方式二、使用Fastjson2替换SpringMvc的全局序列化与反序列化器，并解决反序列化时Long精度丢失问题

引入依赖

<!-- spirngboot2.6.9 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>


<!-- fastjson2 -->
<dependency>
    <groupId>com.alibaba.fastjson2</groupId>
    <artifactId>fastjson2-extension-spring5</artifactId>
    <version>2.0.29</version>
</dependency>

SpringBoot添加配置文件

@Configuration
public class Fastjson2Webmvc implements WebMvcConfigurer {

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        FastJsonConfig config = new FastJsonConfig();
        config.setCharset(StandardCharsets.UTF_8);
        config.setDateFormat("yyyy-MM-dd HH:mm:ss");
        config.setWriterFeatures(
                //long 转 string 丢失精度问题
                JSONWriter.Feature.WriteLongAsString,
                // 保留map空的字段
                JSONWriter.Feature.WriteMapNullValue,
                //将List类型的null转成[]
                JSONWriter.Feature.WriteNullListAsEmpty,
                //将String类型的null转成""
                JSONWriter.Feature.WriteNullStringAsEmpty,
                //将Boolean类型的null转成false
                JSONWriter.Feature.WriteNullBooleanAsFalse,
                //日期格式转换
                JSONWriter.Feature.PrettyFormat,
                //将空置输出为缺省值，Number类型的null都输出为0，String类型的null输出为""，数组和Collection类型的输出为[]
                JSONWriter.Feature.NullAsDefaultValue
        );
        fastJsonHttpMessageConverter.setFastJsonConfig(config);
        converters.add(0, fastJsonHttpMessageConverter);
    }

    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        FastJsonJsonView fastJsonJsonView = new FastJsonJsonView();
        //自定义配置...
        FastJsonConfig config = new FastJsonConfig();
        config.setCharset(StandardCharsets.UTF_8);
        config.setDateFormat("yyyy-MM-dd HH:mm:ss");
        config.setReaderFeatures(JSONReader.Feature.FieldBased, JSONReader.Feature.SupportArrayToBean);
        fastJsonJsonView.setFastJsonConfig(config);
        registry.enableContentNegotiation(fastJsonJsonView);
    }
}