springmvc long精度缺失，long转string字符串_longtostringserializer-优快云博客

该博客介绍了如何在Spring MVC中配置和使用自定义消息转换器，包括MappingJackson2HttpMessageConverter和StringHttpMessageConverter，用于处理日期类型和Long类型的序列化与反序列化。同时，展示了如何为LocalDateTime创建自定义转换器，以及针对Long类型设计的转换器，确保在数据转换过程中处理大数值和日期格式的正确性。

    <!-- 返回字符串utf-8编码-->
    <mvc:annotation-driven>
        <!-- 消息转换器 -->
        <mvc:message-converters register-defaults="true">
            <!-- 处理responseBody 里面日期类型 -->
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="objectMapper" ref="customObjectMapper"></property>
            </bean>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes" value="text/html;charset=UTF-8"/>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>
    <bean name="customObjectMapper" class="com.sky.ddt.config.CustomObjectMapper"></bean>

public class CustomObjectMapper extends ObjectMapper {
    public CustomObjectMapper() {
        super();
        // 设置date类型转换
        setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
        // 反序列化忽视不存在属性
        configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES,false);

        SimpleModule simpleModule = new SimpleModule();
        simpleModule.addSerializer(Long.class, ToStringSerializer.instance);
        simpleModule.addSerializer(Long.TYPE, ToStringSerializer.instance);
        simpleModule.addSerializer(LocalDateTime.class,LocalDateTimeToStringSerializer.instance);
        registerModule(simpleModule);

    }
}

LocalDateTimeToStringSerializer是localDateTime转换器，可以参考设计自定义转换

public class LocalDateTimeToStringSerializer extends StdSerializer<LocalDateTime> {
    public static final LocalDateTimeToStringSerializer instance = new LocalDateTimeToStringSerializer();

    private LocalDateTimeToStringSerializer() {
        super(LocalDateTime.class);
    }

    @Override
    public void serialize(LocalDateTime dateTime, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
        if (dateTime == null) {
            jsonGenerator.writeNull();
        } else {

            jsonGenerator.writeString(getFormatStr(dateTime));
        }
    }

    private String getFormatStr(LocalDateTime dateTime) {
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        String str = dateTime.format(formatter);
        return str;
    }
}

自定义设计LongToStringSerializer，当long比较大的时候才转字符串

public class LongToStringSerializer extends StdSerializer<Long> {
    public static LongToStringSerializer instance=new LongToStringSerializer();

    public LongToStringSerializer() {
        super(Long.class);
    }

    @Override
    public void serialize(Long value, JsonGenerator gen, SerializerProvider provider) throws IOException {
        if(value==null){
            gen.writeNull();
        }else if(value>Integer.MAX_VALUE||value<Integer.MIN_VALUE){
            gen.writeString(String.valueOf(value));
        }else{
            gen.writeNumber(value);
        }
    }
}