这个问题在这里已有答案:
我使用Jackson ObjectMapper将对象层次结构序列化为json String . 之后我想将对象反序列化 . 我有例外如下 .
重要的是 APINewDealArrangementImpl class hierarchy is out of the scope of my changes - 它是外部库的一部分 . 在这种情况下 I'm not able to implement default constructor nor use @JsonCreator annotion .
我怎样才能避免"No suitable constructor found"异常?是否可以使用Jackson API中的某些自定义 TypeResolverBuilder
实现或其他功能来解决此问题?感谢帮助 .
org.codehaus.jackson.map.JsonMappingException: No suitable constructor found for type [simple type, class com.tzero.api.transactions.TransactionState]: can not instantiate from JSON object (need to add/enable type information?)
at [Source: java.io.StringReader@57ac3379; line: 4, column: 5] (through reference chain: com.tzero.api.java.transactions.APINewDealArrangementImpl["state"])
at org.codehaus.jackson.map.JsonMappingException.from(JsonMappingException.java:163)
at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObjectUsingNonDefault(BeanDeserializer.java:746)
at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:683)
at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
at org.codehaus.jackson.map.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:299)
at org.codehaus.jackson.map.deser.SettableBeanProperty$MethodProperty.deserializeAndSet(SettableBeanProperty.java:414)
at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:697)
at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2732)
at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1863)
2 回答
您可以使用"mixin"在其他类上提供注释 . 这有点奇怪,但非常有用 .
所以这里没有关于TargetData的Jackson注释,注释来自TargetDataMixin(并且完全忽略了TargetDataMixin的实现)
您需要在类中添加no args构造函数 . Jackson需要创建一个类的实例,为了做到这一点,它需要类有一个没有args的构造函数 .