使用 objectMapper 将 JSON 日期格式反序列化为 ZonedDateTime

Question

背景

1. 我有以下 JSON（来自 Kafka 的消息）

{
      "markdownPercentage": 20,
      "currency": "SEK",
      "startDate": "2019-07-25"
}

1. 我有以下（生成的 JSON 模式）POJO（我无法更改 POJO，因为它是公司的共享资源）

public class Markdown {
    @JsonProperty("markdownPercentage")
    @NotNull
    private Integer markdownPercentage = 0;
    @JsonProperty("currency")
    @NotNull
    private String currency = "";
    @JsonFormat(
        shape = Shape.STRING,
        pattern = "yyyy-MM-dd"
    )
    @JsonProperty("startDate")
    @NotNull
    private ZonedDateTime startDate;

    // Constructors, Getters, Setters etc.

}

1. 我们的应用程序是一个 Spring Boot 应用程序，它使用 Spring Cloud Stream 从 Kafka 读取 JSON 消息 (1) 并使用 POJO (2)，然后对其进行处理。

问题

当应用程序尝试将消息反序列化到对象时，它会抛出以下异常

com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type `java.time.ZonedDateTime` from String "2019-07-25": Failed to deserialize java.time.ZonedDateTime: (java.time.DateTimeException) Unable to obtain ZonedDateTime from TemporalAccessor: {},ISO resolved to 2019-07-25 of type java.time.format.Parsed
 at [Source: (String)"{"styleOption":"so2_GreyMelange_1563966403695_1361997740","markdowns":[{"markdownPercentage":20,"currency":"SEK","startDate":"2019-07-25"},{"markdownPercentage":20,"currency":"NOK","startDate":"2019-07-25"},{"markdownPercentage":20,"currency":"CHF","startDate":"2019-07-25"}]}"; line: 1, column: 126] (through reference chain: com.bestseller.generated.interfacecontracts.kafkamessages.pojos.markdownScheduled.MarkdownScheduled["markdowns"]->java.util.ArrayList[0]->com.bestseller.generated.interfacecontracts.kafkamessages.pojos.markdownScheduled.Markdown["startDate"])

    at com.fasterxml.jackson.databind.exc.InvalidFormatException.from(InvalidFormatException.java:67)
    at com.fasterxml.jackson.databind.DeserializationContext.weirdStringException(DeserializationContext.java:1549)
    at com.fasterxml.jackson.databind.DeserializationContext.handleWeirdStringValue(DeserializationContext.java:911)
    at com.fasterxml.jackson.datatype.jsr310.deser.JSR310DeserializerBase._handleDateTimeException(JSR310DeserializerBase.java:80)
    at com.fasterxml.jackson.datatype.jsr310.deser.InstantDeserializer.deserialize(InstantDeserializer.java:212)
    at com.fasterxml.jackson.datatype.jsr310.deser.InstantDeserializer.deserialize(InstantDeserializer.java:50)
    at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:127)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:288)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:286)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:245)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:27)
    at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:127)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:288)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4013)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3004)
    at com.bestseller.mps.functional.TestingConfiguration.test(TestingConfiguration.java:42)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: java.time.DateTimeException: Unable to obtain ZonedDateTime from TemporalAccessor: {},ISO resolved to 2019-07-25 of type java.time.format.Parsed
    at java.base/java.time.ZonedDateTime.from(ZonedDateTime.java:566)
    at com.fasterxml.jackson.datatype.jsr310.deser.InstantDeserializer.deserialize(InstantDeserializer.java:207)
    ... 35 more
Caused by: java.time.DateTimeException: Unable to obtain ZoneId from TemporalAccessor: {},ISO resolved to 2019-07-25 of type java.time.format.Parsed
    at java.base/java.time.ZoneId.from(ZoneId.java:463)
    at java.base/java.time.ZonedDateTime.from(ZonedDateTime.java:554)
    ... 36 more

当前代码

我定义了以下 objectMapper

/**
     * Date mapper.
     *
     * @return the {@link ObjectMapper}
     */
    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.registerModule(new JavaTimeModule());
        mapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd"));
        return mapper;
    }

问题

我了解 POJO 中生成的 ZonedDateTime 需要一个源消息中不存在的“时间”元素。我只能控制 objectMapper。是否有任何可能的配置可以使这项工作？

注意

如果反序列化 POJO 中的时间元素“假定”为 startOfDay 即“00.00.00.000Z”，我很好

Answer 1

我只能控制ObjectMapper。是否有任何可能的配置可以使这项工作？

只要您对时间和时区的默认值感到满意，您就可以使用自定义反序列化器来解决它：

public class ZonedDateTimeDeserializer extends JsonDeserializer<ZonedDateTime> {

    @Override
    public ZonedDateTime deserialize(JsonParser jsonParser,
                                     DeserializationContext deserializationContext)
                                     throws IOException {

        LocalDate localDate = LocalDate.parse(
                jsonParser.getText(), 
                DateTimeFormatter.ISO_LOCAL_DATE);

        return localDate.atStartOfDay(ZoneOffset.UTC);
    }
}

然后将其添加到模块中，并将模块注册到您的ObjectMapper 实例：

SimpleModule module = new SimpleModule();
module.addDeserializer(ZonedDateTime.class, new ZonedDateTimeDeserializer());

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(module);

---

如果将反序列化器添加到模块中不适合您（从某种意义上说，此配置将应用于其他 ZonedDateTime 实例），那么您可以依靠 mix-ins 来定义反序列化器将应用于哪些字段.首先定义一个mix-in接口，如下图：

public interface MarkdownMixIn {

    @JsonDeserialize(using = ZonedDateTimeDeserializer.class)
    ZonedDateTime getDate();
}

然后将mix-in接口绑定到想要的类：

ObjectMapper mapper = new ObjectMapper();
mapper.addMixIn(Markdown.class, MarkdownMixIn.class);

Answer 2

问题：我想将日期从 json 解析为 java LocalDateTime/ZonedDateTime 对象。 ZonedDateTimeSerializer 存在，但 ZonedDateTimeDeserializer 不存在。因此，我创建了一个自定义 ZonedDateTimeDeserializer。

  public static final String ZONED_DATE_TIME_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSSz"; 

  @Getter
  @Setter
  @JsonSerialize(using = ZonedDateTimeSerializer.class)
  @JsonDeserialize(using = ZonedDateTimeDeserializer.class) // Doesn't exist, So I created a custom ZonedDateDeserializer utility class.
  @JsonFormat(pattern = ZONED_DATE_TIME_FORMAT)
  @JsonProperty("lastUpdated")
  private ZonedDateTime lastUpdated;

解决方案：我最终得到了更简单且更少的代码行。

反序列化 ZonedDateTime的实用程序类：

/**
 * Custom {@link ZonedDateTime} deserializer.
 *
 * @param jsonParser             for extracting the date in {@link String} format.
 * @param deserializationContext for the process of deserialization a single root-level value.
 * @return {@link ZonedDateTime} object of the date.
 * @throws IOException throws I/O exceptions.
 */
public class ZonedDateTimeDeserializer extends JsonDeserializer<ZonedDateTime> {

    @Override
    public ZonedDateTime deserialize(JsonParser jsonParser, DeserializationContext deserializationContext)
            throws IOException {

        return ZonedDateTime.parse(jsonParser.getText(), DateTimeFormatter.ofPattern(ZONED_DATE_TIME_FORMAT));
    }
}

如果您改用 LocalDateTime 会怎样。在这种情况下就更容易了，反序列化器和序列化器类都已经提供给我们了。不需要上面定义的自定义实用程序类：

  @Getter
  @Setter
  @JsonSerialize(using = LocalDateSerializer.class)
  @JsonDeserialize(using = LocalDateTimeDeserializer.class)
  @JsonFormat(pattern = ZONED_DATE_TIME_FORMAT) //Specify the format you want: "yyyy-MM-dd'T'HH:mm:ss.SSS"
  @JsonProperty("created")
  private LocalDateTime created;

对研究也有帮助的其他链接： ideas that led to this solution

关键词：json格式localDateTime zonedDateTime

Answer 3

遗憾的是，如果不将 POJO 的类型更改为 LocalDate，这将很困难。

我能想到的最接近的解决方案是为杰克逊写一个自定义的JsonDeserializer，这绝对不是那种事情的好习惯。

见https://fasterxml.github.io/jackson-databind/javadoc/2.3.0/com/fasterxml/jackson/databind/JsonDeserializer.html

Answer 4

您可以编写自己的反序列化器，如@cassiomolin 答案所示。但也有另一种选择。在堆栈跟踪中，我们有 DeserializationContext.weirdStringException 方法，它允许我们为 DeserializationProblemHandler 提供处理奇怪的字符串值。见下例：

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonFormat.Shape;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.deser.DeserializationProblemHandler;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import java.io.IOException;
import java.time.LocalDate;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.TimeZone;

public class AppJson {

    public static void main(String[] args) throws IOException {
        ObjectMapper mapper = new ObjectMapper();
        // override default time zone if needed
        mapper.setTimeZone(TimeZone.getTimeZone("America/Los_Angeles"));

        mapper.registerModule(new JavaTimeModule());
        mapper.addHandler(new DeserializationProblemHandler() {
            @Override
            public Object handleWeirdStringValue(DeserializationContext ctxt, Class<?> targetType,
                String valueToConvert, String failureMsg) {
                LocalDate date = LocalDate.parse(valueToConvert, DateTimeFormatter.ISO_DATE);
                return date.atStartOfDay(ctxt.getTimeZone().toZoneId());
            }
        });
        String json = "{\"startDate\": \"2019-07-25\"}";
        Markdown markdown = mapper.readValue(json, Markdown.class);
        System.out.println(markdown);
    }
}

上面的代码打印：

Markdown{startDate=2019-07-25T00:00-07:00[America/Los_Angeles]}

Answer 5

很遗憾，您不能默认将String Object 反序列化为ZonedDateTime 格式。但是您可以通过两种方式克服这个问题。

01路

在POJO 类中将ZonedDateTime 类型更改为LocalDate 类型并将值作为字符串传递03-06-2012

方式02

但如果你必须用时区存储日期和时间，那么你必须采取以下方法来克服

步骤 01

使用 DateTimeFormat 为ZonedDateTime 反序列化创建一个类

public class ZonedDateTimeDeserializer extends JsonDeserializer<ZonedDateTime> {

    @Override
    public ZonedDateTime deserialize(JsonParser p, DeserializationContext ctxt) throws IOException, JsonProcessingException {

        DateTimeFormatter dateTimeFormatter=DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss z");
        LocalDate localDate = LocalDate.parse(p.getText(),dateTimeFormatter);

        return localDate.atStartOfDay(ZoneOffset.UTC);
    }
}

步骤 02

在@JsonDeserialize 方法级别注释的支持下，您必须在 POJO 类中使用带有受影响字段的 Deserialize 类。

@JsonDeserialize(using = ZonedDateTimeDeserializer.class)
private ZonedDateTime startDate;

步骤 03

以上述格式将值作为字符串传递给 ZonedDateTimeDeserializer 类

       "startDate" : "09-03-2003 10:15:00 Europe/Paris"

Answer 6

您需要将您的String 变量startDate 转换为ZonedDateTimne，然后它将被转换并保存到您的数据库或其他任何东西。

由于即将到来的json startDate 是字符串格式，并且您已经说过您无法更改POJO，因此您需要在将其分配给private ZonedDateTime startDate;之前对其进行转换

你可以像下面的例子那样做：

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss a z");
ZonedDateTime dateTime = ZonedDateTime.parse("2019-03-27 10:15:30 AM +05:30", formatter);
System.out.println(dateTime);