jackson多态反序列化
jackson和类型层次结构我遇到了以下问题。 我正在序列化一个SubA
类,它将Base
扩展为一个String
,然后尝试将它去除它。 当然在编译时,系统不知道它是Base
还是SubA
所以我期待一个Base
,如果它是SubA
,之后会做一些其他的操作。
我的Base
类看起来像:
@JsonTypeInfo( use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type") @JsonSubTypes({ @Type(value = SubA.class, name = "SubA") }) public class Base { protected String command; // +get +set protected String type; // +get +set }
……以及从Base
派生的类:
@JsonTypeName("SubA") public class SubA extends Base { private AnotherClass anotherClass; // +get +set private String test; // +get +set @JsonIgnore @Override public String getType() { return "SubA"; } }
…而我正在尝试执行以下代码:
ObjectMapper mapper = new ObjectMapper(); ObjectWriter ow = mapper.writer().withDefaultPrettyPrinter(); Base payload = new SubA(); // + setting anotherClass as well as test variables String requestStringSend = ow.writeValueAsString(payload); System.out.println("Sending: " + requestStringSend); Base received = mapper.readValue(requestStringSend, Base.class); String requestStringReceived = ow.writeValueAsString(received); System.out.println("Received: " + requestStringReceived);
String requestStringSend
是:
Sending: { "command" : "myCommand", "type" : "SubA", "anotherClass" : { "data" : "someData" }, "test" : "test123" }
但我一遍又一遍地得到同样的错误。 映射器现在知道如何处理anotherClass
参数 – 它在Base
中不存在。 但我认为映射器会将其转换为SubA
类?
Exception in thread "main" org.codehaus.jackson.map.exc.UnrecognizedPropertyException: Unrecognized field "anotherClass" (Class com.test.Base), not marked as ignorable at [Source: java.io.StringReader@1256ea2; line: 4, column: 21] (through reference chain: com.test.Base["anotherClass"]) at org.codehaus.jackson.map.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:53) at org.codehaus.jackson.map.deser.StdDeserializationContext.unknownFieldException(StdDeserializationContext.java:267) at org.codehaus.jackson.map.deser.std.StdDeserializer.reportUnknownProperty(StdDeserializer.java:649) at org.codehaus.jackson.map.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:635) at org.codehaus.jackson.map.deser.BeanDeserializer.handleUnknownProperty(BeanDeserializer.java:1355) at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:717) at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580) at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2723) at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1854) at com.test.Foo.main(Foo.java:32)
我看了下面的问题/资源:
- 使用Jackson将Json反序列化为另一个类层次结构
- http://wiki.fasterxml.com/JacksonPolymorphicDeserialization
您的代码看起来正确用例。 一个可能的问题是你可能会意外地使用jackson2注释与jackson1 ObjectMapper
(我可以看到后者是jackson从包名称例外)。 注释和映射器的版本必须匹配; 否则注释将被忽略,这将解释您所看到的问题。