[英]Jackson polymorphic deserialization
杰克逊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:
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Jackson 2注释与Jackson 1 ObjectMapper
(我可以看到后者是杰克逊来自包名称的例外)。 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。
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