这是我的课程:
@XmlRootElement(name="Zoo")
class Zoo {
//@XmlElementRef
public Collection<? extends Animal> animals;
}
@XmlAccessorType(XmlAccessType.FIELD)
@XmlSeeAlso({Bird.class, Cat.class, Dog.class})
@XmlDiscriminatorNode("@type")
abstract class Animal {
@XmlElement
public String name;
}
@XmlDiscriminatorValue("Bird")
@XmlRootElement(name="Bird")
class Bird extends Animal {
@XmlElement
public String wingSpan;
@XmlElement
public String preferredFood;
}
@XmlDiscriminatorValue("Cat")
@XmlRootElement(name="Cat")
class Cat extends Animal {
@XmlElement
public String favoriteToy;
}
@XmlDiscriminatorValue("Dog")
@XmlRootElement(name="Dog")
class Dog extends Animal {
@XmlElement
public String breed;
@XmlElement
public String leashColor;
}
这是序列化的 JSON:
{
"animals": [
{
"type": "Bird",
"name": "bird-1",
"wingSpan": "6 feets",
"preferredFood": "food-1"
},
{
"type": "Cat",
"name": "cat-1",
"favoriteToy": "toy-1"
},
{
"type": "Dog",
"name": "dog-1",
"breed": "bread-1",
"leashColor": "black"
}
]
}
这是反序列化程序代码:
public static <T> T Deserialize_Moxy(String jsonStr, Class<?>[] cl) throws JAXBException {
InputStream is = new ByteArrayInputStream(jsonStr.getBytes());
JAXBContext jc = JAXBContext.newInstance(cl);
Unmarshaller unmarshaller = jc.createUnmarshaller();
// Marshal to JSON
unmarshaller.setProperty(MarshallerProperties.MEDIA_TYPE, "application/json");
unmarshaller.setProperty(MarshallerProperties.JSON_INCLUDE_ROOT, false);
@SuppressWarnings("unchecked")
T obj = (T)unmarshaller.unmarshal(is);
return obj;
}
这是一个例外:
Exception in thread "main" javax.xml.bind.UnmarshalException
- with linked exception:
[Exception [EclipseLink-25008] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: A descriptor with default root element was not found in the project]
at org.eclipse.persistence.jaxb.JAXBUnmarshaller.handleXMLMarshalException(JAXBUnmarshaller.java:1014)
at org.eclipse.persistence.jaxb.JAXBUnmarshaller.unmarshal(JAXBUnmarshaller.java:147)
at com.bp.samples.json.generics.Foo.Deserialize_Moxy(Foo.java:271)
at com.bp.samples.json.generics.Foo.main(Foo.java:111)
Caused by: Exception [EclipseLink-25008] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: A descriptor with default root element was not found in the project
at org.eclipse.persistence.exceptions.XMLMarshalException.noDescriptorWithMatchingRootElement(XMLMarshalException.java:143)
at org.eclipse.persistence.internal.oxm.record.SAXUnmarshallerHandler.startElement(SAXUnmarshallerHandler.java:222)
at org.eclipse.persistence.internal.oxm.record.json.JSONReader.parseRoot(JSONReader.java:161)
at org.eclipse.persistence.internal.oxm.record.json.JSONReader.parse(JSONReader.java:118)
at org.eclipse.persistence.internal.oxm.record.SAXUnmarshaller.unmarshal(SAXUnmarshaller.java:827)
at org.eclipse.persistence.internal.oxm.record.SAXUnmarshaller.unmarshal(SAXUnmarshaller.java:350)
at org.eclipse.persistence.internal.oxm.record.SAXUnmarshaller.unmarshal(SAXUnmarshaller.java:334)
at org.eclipse.persistence.oxm.XMLUnmarshaller.unmarshal(XMLUnmarshaller.java:407)
at org.eclipse.persistence.jaxb.JAXBUnmarshaller.unmarshal(JAXBUnmarshaller.java:133)
... 2 more
还有一个关于序列化 JSON 的问题:有没有办法让 JSON 序列化程序发布“@type”而不是“type”。目前,它看起来像具有“类型”属性的对象。如果我们可以用“@”来装饰它,那么它更像是一个类型信息而不是一个属性会更明显。
谢谢,贝扎德