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Springboot中Instant时间传参及序列化详解

作者：杨某人信了你的邪

这篇文章主要介绍了Springboot中Instant时间传参及序列化详解,Instant是Java8引入的一个精度极高的时间类型,可以精确到纳秒,但实际使用的时候不需要这么高的精确度,通常到毫秒就可以了,需要的朋友可以参考下

Instant时间传参及序列化

在部分场景中，后台的时间属性用的不是Date或Long，而是Instant，Java8引入的一个精度极高的时间类型，可以精确到纳秒，但实际使用的时候不需要这么高的精确度，通常到毫秒就可以了。

而在前后端传参的时候需要对Instant类型进行序列化及反序列化等处理，默认情况下，ObjectMapper是不支持序列化Instant类型的，需要注册JavaTimeModule才行，而且序列化的结果也不是时间戳，测试如下

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import lombok.extern.slf4j.Slf4j;
import org.junit.jupiter.api.Test;

import java.time.Instant;

/**
 * Instant Jackson测试
 *
 * @author yangguirong
 */
@Slf4j
public class InstantTest {

    ObjectMapper objectMapper = new ObjectMapper();

    @Test
    void serializeTest() throws JsonProcessingException {
        objectMapper.registerModule(new JavaTimeModule());
        String str = objectMapper.writeValueAsString(Instant.now());
        log.info("serializeTest: {}", str);
        // serializeTest: 1691208180.052185000
    }

    @Test
    void deserializeTest() throws JsonProcessingException {
        objectMapper.registerModule(new JavaTimeModule());
        Instant instant = objectMapper.readValue("1691208180.052185000", Instant.class);
        log.info("deserializeTest: {}", instant);
        // deserializeTest: 2023-08-05T04:03:00.052185Z
    }
}

想要将其序列化为毫秒时间戳，需要对序列化及反序列化进行自定义

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.module.SimpleModule;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.time.Instant;

/**
 * 自定义Instant序列化及反序列
 *
 * @author yangguirong
 */
public class InstantMillsTimeModule extends SimpleModule {

    public InstantMillsTimeModule() {
        this.addSerializer(Instant.class, new InstantMillisecondsSerializer());
        this.addDeserializer(Instant.class, new InstantMillisecondsDeserializer());
    }

    public static class InstantMillisecondsSerializer extends JsonSerializer<Instant> {
        @Override
        public void serialize(Instant instant, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
            if (instant == null) {
                jsonGenerator.writeNull();
            } else {
                jsonGenerator.writeNumber(instant.toEpochMilli());
            }
        }
    }
    
    @Slf4j
    public static class InstantMillisecondsDeserializer extends JsonDeserializer<Instant> {
        @Override
        public Instant deserialize(JsonParser p, DeserializationContext ctxt) throws IOException, JsonProcessingException {
            try {
                long mills = p.getValueAsLong();
                return mills > 0 ? Instant.ofEpochMilli(mills) : null;
            } catch (Exception e) {
                log.error("Instant类型反序列化失败！val: {}, message: {}", p.getText(), e.getMessage());
            }
            return null;
        }
    }
}

再来测试一下自定义的序列化及反序列化方式

import com.example.websocket.config.InstantMillsTimeModule;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import lombok.extern.slf4j.Slf4j;
import org.junit.jupiter.api.Test;

import java.time.Instant;

/**
 * Instant Jackson测试
 *
 * @author yangguirong
 */
@Slf4j
public class InstantTest {

    ObjectMapper objectMapper = new ObjectMapper();

    @Test
    void serializeTest() throws JsonProcessingException {
        objectMapper.registerModule(new JavaTimeModule());
        String str = objectMapper.writeValueAsString(Instant.now());
        log.info("serialize: {}", str);
        // serialize: 1691208180.052185000
    }

    @Test
    void deserializeTest() throws JsonProcessingException {
        objectMapper.registerModule(new JavaTimeModule());
        Instant instant = objectMapper.readValue("1691208180.052185000", Instant.class);
        log.info("deserialize: {}", instant);
        // deserialize: 2023-08-05T04:03:00.052185Z
    }

    @Test
    void millsSerializeTest() throws JsonProcessingException {
        objectMapper.registerModule(new InstantMillsTimeModule());
        String str = objectMapper.writeValueAsString(Instant.now());
        log.info("millsSerializeTest: {}", str);
        // millsSerializeTest: 1691208541018
    }

    @Test
    void millsDeserializeTest() throws JsonProcessingException {
        objectMapper.registerModule(new InstantMillsTimeModule());
        Instant instant = objectMapper.readValue("1691208541018", Instant.class);
        log.info("millsDeserializeTest: {}", instant);
        // deserialize: 2023-08-05T04:09:01.018Z
    }
}

可以看到，结果是符合预期的，可以在毫秒时间戳和Instant之间相互转换。

在后台配置SpringBoot的时候，需要考虑两种情况，一种就是Instant作为RequestParam/PathVariable的情况，另一种是RequestBody/ResponseBody的情况。前者借助转换器实现，配置如下

import org.springframework.context.annotation.Configuration;
import org.springframework.core.convert.converter.Converter;
import org.springframework.format.FormatterRegistry;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.time.Instant;

/**
 * web mvc设置
 *
 * @author yangguirong
 */
@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

    @Override
    public void addFormatters(FormatterRegistry registry) {
        registry.addConverter(instantConvert());
    }

    public Converter<String, Instant> instantConvert() {
        // 不能替换为lambda表达式
        return new Converter<String, Instant>() {
            @Override
            public Instant convert(String source) {
                if (StringUtils.hasText(source)) {
                    return Instant.ofEpochMilli(Long.parseLong(source));
                }
                return null;
            }
        };
    }
}

后者如果是局部配置，则在具体的实体类属性上添加@JsonSerialize和@JsonDeserialize注解，在注解中指定序列化器和反序列化器即可。如果是全局配置，则可以按照如下方式进行配置，将InstantMillsTimeModule注册为Bean，这个Bean会在JacksonAutoConfiguration中的StandardJackson2ObjectMapperBuilderCustomizer被自动注入，然后进行注册。

import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.SerializationFeature;
import org.springframework.boot.autoconfigure.AutoConfigureBefore;
import org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;
import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * Jackson配置
 *
 * @author yangguirong
 */
@Configuration
@AutoConfigureBefore(JacksonAutoConfiguration.class)
public class JacksonCustomizerConfig {

    @Bean
    public Jackson2ObjectMapperBuilderCustomizer jacksonModuleRegistryCustomizer() {
        return jacksonObjectMapperBuilder -> jacksonObjectMapperBuilder.featuresToDisable(
                DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, SerializationFeature.FAIL_ON_EMPTY_BEANS
        );
    }

    @Bean
    public InstantMillsTimeModule instantMillsTimeModule() {
        return new InstantMillsTimeModule();
    }
}

简单的接口测试

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.*;

import java.time.Instant;

/**
 * instant测试
 *
 * @author yangguirong
 */
@Slf4j
@RequestMapping("instant")
@RestController
public class InstantTestController {

    @GetMapping("getInstant")
    public Instant getInstant() {
        return Instant.now();
    }

    @PutMapping("setInstant")
    public void setInstant(@RequestParam Instant instant) {
        log.info("setInstant: {}", instant);
    }

    @GetMapping("getInstantDemoVO")
    public DemoVO getInstantDemoVO() {
        return new DemoVO(Instant.now());
    }

    @PutMapping("setInstantDemoVO")
    public void setInstantDemoVO(@RequestBody DemoVO vo) {
        log.info("setInstantDemoVO:{}", vo);
    }

    @Data
    @NoArgsConstructor
    @AllArgsConstructor
    static class DemoVO {
        private Instant instant;
    }
}

到此这篇关于Springboot中Instant时间传参及序列化详解的文章就介绍到这了,更多相关Instant时间传参及序列化内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！

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