如何优雅的接收时间类型参数?

时间的格式有很多种，比较常用的有时间戳格式、UTC时间格式、标准时间格式等，而且时间参数出现的位置可能在URL上，可能在Body中，也可能在Header中，我们创建一个简单的接口，想通过@PathVariable接收Date类型的时间参数，和通过@RequestParam接收LocalDateTime类型的时间参数,并且想通过@RequestBody来接收JSON中的时间参数:

jsGET http://localhost:80/time/2023-09-10?time=2023-09-15 11:11:11
Accept: application/json
Content-Type: application/json

{
    "id":1,
    "now":"2023-09-15 13:50:10",
    "day":"2023-09-15",
    "time": "2023-09-15 13:50:10",
    "timeStack": 1694757010407
}

SpringBoot默认是用String接收的，如果直接用LocalDateTime或者Date来接收会报一个类型转换错误。

当然我们可以使用String接收，再手动转成对应的时间格式，但是不够优雅，接下来我们看看不同级别是如何处理时间字段的。

青铜解决方案

青铜解析方案存在的问题：

1. @InitBinder作用域只是当前的Controller，如果我用100个Controller难道我要写100个@InitBinder
2. @JsonFormat 也是每个字段上都要增加个注解，而且只能支持一种时间格式，如果我们还要支持时间戳格式就没法做到了。

白银解决方案

针对青铜解析方案存在的问题1,我们的解决方案是使用@ControllerAdvice，这样就不用在每个Controller上都添加@InitBinder了

java@ControllerAdvice
public class GlobalControllerAdvice {

    @InitBinder
    public void initBinder(WebDataBinder binder) {
        binder.registerCustomEditor(LocalDateTime.class, new PropertyEditorSupport() {
            @Override
            public void setAsText(String text) {
                setValue(DateUtil.parseLocalDateTime(text));
            }
        });
        binder.registerCustomEditor(Date.class, new PropertyEditorSupport() {
            @Override
            public void setAsText(String text) {
                setValue(DateUtil.parse(text,NORM_DATETIME_PATTERN,NORM_DATE_PATTERN));
            }
        });
    }
}

java@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Bean
    @Primary
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        SimpleModule module = new SimpleModule();
        module.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer());
        module.addSerializer(Date.class, new DateTimeSerializer());
        module.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer());
        module.addDeserializer(Date.class, new DateTimeDeserializer());
        mapper.registerModule(module);
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        return JsonUtils.getMapper();
    }
}

public class DateTimeDeserializer extends StdDeserializer<Date> {

    public DateTimeDeserializer() {
        this(null);
    }

    public DateTimeDeserializer(Class<?> vc) {
        super(vc);
    }

    @Override
    public Date deserialize(JsonParser jp, DeserializationContext ctx)
            throws IOException {
        String value = jp.getValueAsString();
            return DateUtil.parse(value,NORM_DATETIME_PATTERN,NORM_DATE_PATTERN);
    }
}

public class DateTimeSerializer extends StdSerializer<Date> {

    public DateTimeSerializer() {
        this(null);
    }

    public DateTimeSerializer(Class<Date> t) {
        super(t);
    }

    @Override
    public void serialize(Date value, JsonGenerator jgen, SerializerProvider provider) throws IOException {
        jgen.writeString(DateUtil.format(value, DatePattern.NORM_DATETIME_PATTERN));
    }
}

public class LocalDateTimeDeserializer extends StdDeserializer<LocalDateTime> {

    public LocalDateTimeDeserializer() {
        this(null);
    }

    public LocalDateTimeDeserializer(Class<?> vc) {
        super(vc);
    }

    @Override
    public LocalDateTime deserialize(JsonParser jp, DeserializationContext ctx)
            throws IOException {
        String value = jp.getValueAsString();
        if (StrUtil.isNumeric(value)) {
            Date date = new Date(jp.getLongValue());
            return LocalDateTime.ofInstant(date.toInstant(),  ZoneId.of("Asia/Shanghai"));
        } else {
            return DateUtil.parseLocalDateTime(value);
        }
    }
}

public class LocalDateTimeSerializer extends StdSerializer<LocalDateTime> {

    public LocalDateTimeSerializer() {
        this(null);
    }

    public LocalDateTimeSerializer(Class<LocalDateTime> t) {
        super(t);
    }

    @Override
    public void serialize(LocalDateTime value, JsonGenerator jgen, SerializerProvider provider) throws IOException {
        jgen.writeString(LocalDateTimeUtil.formatNormal(value));
    }
}

王者解决方案

java@Configuration
public class WebConfig  {
    @Bean
    @Primary
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        SimpleModule module = new SimpleModule();
        module.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer());
        module.addSerializer(Date.class, new DateTimeSerializer());
        module.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer());
        module.addDeserializer(Date.class, new DateTimeDeserializer());
        mapper.registerModule(module);
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        return JsonUtils.getMapper();
    }

    @Bean
    public Converter<String, LocalDateTime> stringLocalDateTimeConverter() {
        return new Converter<String, LocalDateTime>() {
            @Override
            public LocalDateTime convert(String source) {
                if (StrUtil.isNumeric(source)) {
                    return LocalDateTimeUtil.of(Long.parseLong(source));
                } else {
                    return DateUtil.parseLocalDateTime(source);
                }
            }
        };

    }

    @Bean
    public Converter<String, Date> stringDateTimeConverter() {
        return new Converter<String, Date>() {
            @Override
            public Date convert(String source) {
                if (StrUtil.isNumeric(source)) {
                    return new Date(Long.parseLong(source));
                } else {
                    return DateUtil.parse(source);
                }
            }
        };
    }

}

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