一.BUG 描述

1.现象

com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type java.util.Date from String "2023-11-30 22:31:23": not a valid representation (error: Failed to parse Date value '2023-11-30 22:31:23': Cannot parse date "2023-11-30 22:31:23": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSSX', parsing fails (leniency? null)) at [Source: (StringReader); line: 1, column: 634] (through reference chain: com.kwan.springbootkwan.entity.csdn.BusinessInfoResponse["data"]->com.kwan.springbootkwan.entity.csdn.BusinessInfoResponse$ArticleData["list"]->java.util.ArrayList[0]->com.kwan.springbootkwan.entity.csdn.BusinessInfoResponse$ArticleData$Article["postTime"]) at com.fasterxml.jackson.databind.exc.InvalidFormatException.from(InvalidFormatException.java:67)

2.原因

实体类是 Date 类型,但是 json 字符串是 yyyy-MM-dd'T'HH:mm:ss.SSSX 的时间字段,时间格式不匹配导致,json 字符串转实体类失败了。

二.解决方案

1.添加依赖

<dependency>
	<groupId>com.fasterxml.jackson.core</groupId>
	<artifactId>jackson-annotations</artifactId>
	<version>2.8.8</version>
</dependency>

<dependency>
	<groupId>com.fasterxml.jackson.core</groupId>
	<artifactId>jackson-databind</artifactId>
	<version>2.8.8</version>
</dependency>

<dependency>
	<groupId>org.codehaus.jackson</groupId>
	<artifactId>jackson-mapper-asl</artifactId>
	<version>1.9.13</version>
</dependency>

2.添加注解

添加@JsonFormat 注解,指定时间格式为 yyyy-MM-dd HH:mm:ss 就不会报错了,

@TableField(value = "postTime")
@ApiModelProperty(value = "时间")
@JsonFormat(locale = "zh", timezone = "GMT+8", pattern = "yyyy-MM-dd HH:mm:ss")
public Date postTime;

三.全局配置

1.@JsonComponent

@JsonFormat 注解并不能完全做到全局时间格式化，使用 @JsonComponent 注解自定义一个全局格式化类，分别对 Date 和 LocalDate 类型做格式化处理。

@JsonComponent
public class DateFormatConfig {

    @Value("${spring.jackson.date-format:yyyy-MM-dd HH:mm:ss}")
    private String pattern;

    @Bean
    public Jackson2ObjectMapperBuilderCustomizer jackson2ObjectMapperBuilder() {

 return builder -> {
            TimeZone tz = TimeZone.getTimeZone("UTC");
            DateFormat df = new SimpleDateFormat(pattern);
            df.setTimeZone(tz);
            builder.failOnEmptyBeans(false)
                    .failOnUnknownProperties(false)
                    .featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
                    .dateFormat(df);
        };
    }

    @Bean
    public LocalDateTimeSerializer localDateTimeDeserializer() {
 return new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(pattern));
    }

    @Bean
    public Jackson2ObjectMapperBuilderCustomizer jackson2ObjectMapperBuilderCustomizer() {
 return builder -> builder.serializerByType(LocalDateTime.class, localDateTimeDeserializer());
    }
}

2.自定义

但还有个问题，实际开发中如果我有个字段不想用全局格式化设置的时间样式,那该怎么处理呢?

@Data
public class OrderDTO {

    @JsonFormat(locale = "zh", timezone = "GMT+8", pattern = "yyyy-MM-dd")
    private LocalDateTime createTime;

    @JsonFormat(locale = "zh", timezone = "GMT+8", pattern = "yyyy-MM-dd")
    private Date updateTime;
}

@JsonFormat注解的优先级比较高，会以@JsonFormat注解的时间格式为主。

3.@Configuration

注意：在使用此种配置后，字段手动配置@JsonFormat 注解将不再生效。

@Configuration
public class DateFormatConfig2 {

    @Value("${spring.jackson.date-format:yyyy-MM-dd HH:mm:ss}")
    private String pattern;

    public static DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    @Bean
    @Primary
    public ObjectMapper serializingObjectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer());
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer());
        objectMapper.registerModule(javaTimeModule);
 return objectMapper;
    }

    @Component
    public class DateSerializer extends JsonSerializer<Date> {
        @Override
        public void serialize(Date date, JsonGenerator gen, SerializerProvider provider) throws IOException {
 String formattedDate = dateFormat.format(date);
            gen.writeString(formattedDate);
        }
    }

    @Component
    public class DateDeserializer extends JsonDeserializer<Date> {

        @Override
        public Date deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
 try {
 return dateFormat.parse(jsonParser.getValueAsString());
            } catch (ParseException e) {
 throw new RuntimeException("Could not parse date", e);
            }
        }
    }

    public class LocalDateTimeSerializer extends JsonSerializer<LocalDateTime> {
        @Override
        public void serialize(LocalDateTime value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
            gen.writeString(value.format(DateTimeFormatter.ofPattern(pattern)));
        }
    }

    public class LocalDateTimeDeserializer extends JsonDeserializer<LocalDateTime> {
        @Override
        public LocalDateTime deserialize(JsonParser p, DeserializationContext deserializationContext) throws IOException {
 return LocalDateTime.parse(p.getValueAsString(), DateTimeFormatter.ofPattern(pattern));
        }
    }
}