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 来保存无法识别的字段？

Answer 1

您无法保存无法识别的字段，因为 Jackson 不知道将其映射到哪里。

两件事：

1.) 检查/修改您的对象模型并确保它与 XML 匹配。

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