java - Jackson 异常的序列化和反序列化

Question

JSON nest class data binding正如答案所做的那样，当我对容器进行序列化和反序列化时，我得到了这个异常:

Caused by: org.codehaus.jackson.map.JsonMappingException: Can not find a Value deserializer for abstract type [simple type, class com.xiaonei.wap.ps.model.Container]
at org.codehaus.jackson.map.deser.StdDeserializerProvider._handleUnknownValueDeserializer(StdDeserializerProvider.java:321)
at org.codehaus.jackson.map.deser.StdDeserializerProvider.findValueDeserializer(StdDeserializerProvider.java:116)
at org.codehaus.jackson.map.deser.StdDeserializer.findDeserializer(StdDeserializer.java:260)
at

Answer 1

简单地删除或重命名 type 字段的 setter/getter

public class Container 
{
   private AAnimal animal;

   public AAnimal getAnimal()
   {
      return animal;
   }

   @JsonTypeInfo(use=JsonTypeInfo.Id.NAME, include=JsonTypeInfo.As.EXTERNAL_PROPERTY, property="type")
   @JsonSubTypes({ @Type(value = Cat.class, name = "cat"), @Type(value = Dog.class, name = "dog") })
   public void setAnimal(AAnimal animal)
   {
      this.animal = animal;
   }
}    

public abstract class AAnimal 
{
   public String name;
}  

测试

  String json = "{\"type\":\"cat\", \"animal\" : {\"name\":\"cat-mew\" }}";
  Container val = o.readValue(json, Container.class);
  System.out.println(o.writeValueAsString(val));  

输出是

{"animal":{"name":"cat-mew"},"type":"cat"}