Jackson XML 反序列化 - 保存无法识别的字段

Question

我正在使用 Jackson 反序列化服务器返回的 XML 文件。我收到 UnrecognizedPropertyException 错误消息“无法识别的字段”“”。

有问题的 XML：

<Identifiers>
    <Identifier type="Organisational Study">Q2736g</Identifier>
    <Identifier type="NCT">NCT00109200</Identifier>
</Identifiers>

堆栈跟踪：

com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "" (class sloan.scraper.Trial$Identifier), not marked as ignorable (3 known properties: , "data2", "type", "data"])
 at [Source: java.io.StringReader@28c2f254; line: 1, column: 547] (through reference chain: sloan.mit.cortellisScraper.Trial["Identifiers"]->sloan.mit.cortellisScraper.Identifier[""])
    at com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:79)
    at com.fasterxml.jackson.databind.DeserializationContext.reportUnknownProperty(DeserializationContext.java:579)
    at com.fasterxml.jackson.databind.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:672)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownProperty(BeanDeserializerBase.java:906)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:328)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
    at com.fasterxml.jackson.databind.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:147)
    at com.fasterxml.jackson.databind.deser.std.ObjectArrayDeserializer.deserialize(ObjectArrayDeserializer.java:18)
    at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:375)
    at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:107)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:308)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2796)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:1942)
    at sloan.mit.cortellisScraper.Main.fetchJson(Main.java:173)
    at sloan.mit.cortellisScraper.Main.main(Main.java:64)

如何使用 Jackson 来拯救未识别的字段？

Answer 1

您不能仅仅因为杰克逊不知道将其映射到哪里而保存无法识别的字段。

2件事：

1.) 检查/修改您的对象模型并确保它与 XML 匹配。

2.) 用 注释您的类@JsonIgnoreProperties(ignoreUnknown=true)以防止发生此错误。但是，无法识别的字段的值将会丢失。