How to convert Json String to java Bean with generics using jackson

Question

class A<T extends Animal>{
  @XmlElement
  T animal;
}

@XmlRootElement(name="animal")
class Animal{
}

//@XmlRootElement(name="Birds")
class Birds extends Animal{
 ArrayList<String> someNames;
relavant fields ..with getter/setter and annotation
}

//@XmlRootElement(name="Fish")
class Fish extends Animal{
relavant fields ..with getter/setter and annotation
}

I could convert Bean to Json String using org.codehaus.jackson . But when I try to convert Json String back to Java Bean using org.codehaus.jackson

JsonFactory jf = new JsonFactory(); 
JsonParser jp = null;

A<Bird> bird = null;
bird = inputMapper.readValue(jp, A.class);

I gets

org.codehaus.jackson.map.exc.UnrecognizedPropertyException: Unrecognized field "someNames" .

I have put @XmlElement annotations on getter and setters.

Found the solution: http://programmerbruce.blogspot.in/2011/05/deserialize-json-with-jackson-into.html — Free Coder, Jun 09 '13 at 18:53

Free Coder · Answer 1 · 2013-06-09T19:22:43.687

Found the solution http://programmerbruce.blogspot.in/2011/05/deserialize-json-with-jackson-into.html

See example 4 on the mentioned link. By putting 2 Annotations @JsonTypeInfo and @JsonSubTypes, the problem is solved.

@JsonTypeInfo(
        use = JsonTypeInfo.Id.NAME,
        include = JsonTypeInfo.As.PROPERTY,
        property = "type")
@JsonSubTypes({
        @JsonSubTypes.Type(value = Birds.class, name = "birds"),
        @JsonSubTypes.Type(value = Fish.class, name = "fish") })
@XmlRootElement(name="animal")
class Animal{
}

Note the "type" parameter in the annotation @JsonTypeInfo.

1) While serializing, "type" param is introduced by the Jackson framework.

In the case of Birds instance "type" is introduced as "animal":{"type":"birds", "":"" ....}

Similarly in the case of Fish "type" is introduced as "animal":{"type":"fish", "":"" ....}

2) While Deserializing, "type" parameter is used by the Jackson Framework to instantiate polymorphic generic instance bean at run time.

How to convert Json String to java Bean with generics using jackson

1 Answers1