Question

我正在运行MOXy 2.5.0并获得ClassCastException XmlAdapter，但仅在尝试输出JSON时; XML输出工作正常。

我有一个看起来像这样的包装类：

@XmlAccessorType(XmlAccessType.NONE)
public abstract class ListWrapper<T> implements List<T>
{
    private List<T> list = new ArrayList<T>();

    @XmlElement
    private Foo foo;  // stuff specific to my problem domain

    public ListWrapper()
    {
    }

    public ListWrapper(Foo foo, List list)
    {
        this.foo = foo;
        this.list = list;
    }

    // ... implementation of List<T> using the list member ...
}

这个类的后代看起来像这样：

@XmlRootElement(name = "recordList")
@XmlAccessorType(XmlAccessType.NONE)
public class RecordList extends ListWrapper<Record>
{
    public RecordList()
    {
        super();
    }

    public RecordList(Foo foo, List<Record> list)
    {
        super(foo, list);
    }

    @Override
    @XmlElementWrapper(name = "records")
    @XmlElement(name = "record", type = Record.class)
    public List<Record> getList()
    {
        return super.getList();
    }
}

然后有一个RecordList的XmlAdapter，如下所示：

public class RecordListAdapter extends XmlAdapter<RecordList, RecordList>
{
    @Override
    public RecordList unmarshal(RecordList v) throws Exception
    {
        return v;
    }

    @Override
    public RecordList marshal(RecordList v) throws Exception
    {
        return v;
    }
}

最后，有一个类包含RecordList之类的成员，并将其声明为：

@XmlRootElement(name = "container")
@XmlAccessorType(XmlAccessType.NONE)
public class Container
{
    @XmlElement
    @XmlJavaTypeAdapter(RecordListAdapter.class)
    protected RecordList recordList;

    // ... other stuff ...
}

使用引用JAXB实现，这在XML和JSON中都可以正常工作（我们使用Jackson作为JSON逻辑）。随着对MOXy的更改（以及删除Jackson），当我要求JSON输出时，我将得到类似于以下内容的异常跟踪。

javax.xml.bind.MarshalException - with linked exception:[Exception [EclipseLink-25003] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: An error occurred marshalling the object
Internal Exception: Exception [EclipseLink-3001] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.ConversionException
Exception Description: The object [1], of class [class com.example.Record], could not be converted to [class com.example.RecordList].
Internal Exception: java.lang.ClassCastException: com.example.Record cannot be cast to com.example.RecordList]
    at org.eclipse.persistence.jaxb.JAXBMarshaller.marshal(JAXBMarshaller.java:403)
...
Caused by: Exception [EclipseLink-25003] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: An error occurred marshalling the object
Internal Exception: Exception [EclipseLink-3001] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.ConversionException
Exception Description: The object [1], of class [class com.example.Record], could not be converted to [class com.example.RecordList].
Internal Exception: java.lang.ClassCastException: com.example.Record cannot be cast to com.example.RecordList
    at org.eclipse.persistence.exceptions.XMLMarshalException.marshalException(XMLMarshalException.java:97)
...
Caused by: Exception [EclipseLink-3001] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.ConversionException
Exception Description: The object [1], of class [class com.example.Record], could not be converted to [class com.example.RecordList].
Internal Exception: java.lang.ClassCastException: com.example.Record cannot be cast to com.example.RecordList
    at org.eclipse.persistence.exceptions.ConversionException.couldNotBeConverted(ConversionException.java:87)
...
Caused by: java.lang.ClassCastException: com.example.Record cannot be cast to com.example.RecordList
    at com.example.RecordListAdapter.marshal(RecordListAdapter.java:5)
    at org.eclipse.persistence.internal.jaxb.XMLJavaTypeConverter.convertObjectValueToDataValue(XMLJavaTypeConverter.java:172)

我不确定为什么MOXy试图将Record作为RecordList，但看起来好像正在发生的事情。就像我说的那样，这不会发生在JAXB的引用（即Sun）实现上;它只发生在我尝试使用MOXy时。

这里有什么想法吗？感谢。

Answer 1

删除Jackson后，您不再拥有JSON的写入适配器。您需要告诉服务器它应该如何生成JSON。

Answer 2

注意：我是EclipseLink JAXB (MOXy)主管，是JAXB (JSR-222)专家组的成员。

MOXy与您正在使用的其他技术之间的一个区别是，MOXy会将RecordList和ListWrapper视为java.util.List，因为它会实现java.util.List。因此，XmlAdapter无法应用于它，因为它只能应用于集合中的项目。

XmlAdapter和JSON的MOXy异常

2 个答案: