我正在尝试编组一个DataHandler
具有 JAXB (2.1.12) 字段的对象。对于流媒体支持,DataHandler
使用 @ 注释XmlAttachmentRef
。Web 服务上的序列化和流式传输(JBoss 上的 Metro)工作正常,但使用 JAXB 进行简单编组则不行。
这是一个精简的示例:
public class DataHandlerAttachmentSerialization {
@XmlRootElement
static class RootObject {
@XmlElement
@XmlAttachmentRef // Works without this, but required for streaming
DataHandler dataHandler = new DataHandler(
new com.sun.xml.ws.util.ByteArrayDataSource(
" ".getBytes(), "application/octet-stream"));
}
@Test
public void test() throws JAXBException {
JAXBContext context = JAXBContext.newInstance(RootObject.class);
Marshaller marshaller = context.createMarshaller();
StringWriter writer = new StringWriter();
marshaller.marshal(new RootObject(), writer);
Assert.assertNotNull(writer.toString());
}
}
运行此测试会产生以下堆栈跟踪:
javax.xml.bind.MarshalException
- with linked exception:
[com.sun.xml.bind.api.AccessorException: java.lang.NullPointerException]
at com.sun.xml.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:318)
at com.sun.xml.bind.v2.runtime.MarshallerImpl.marshal(MarshallerImpl.java:244)
at javax.xml.bind.helpers.AbstractMarshallerImpl.marshal(AbstractMarshallerImpl.java:96)
...
Caused by: com.sun.xml.bind.api.AccessorException: java.lang.NullPointerException
at com.sun.xml.bind.v2.runtime.XMLSerializer.reportError(XMLSerializer.java:246)
at com.sun.xml.bind.v2.runtime.XMLSerializer.reportError(XMLSerializer.java:261)
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:335)
at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsSoleContent(XMLSerializer.java:593)
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeRoot(ClassBeanInfoImpl.java:320)
at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsRoot(XMLSerializer.java:494)
at com.sun.xml.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:315)
... 25 more
Caused by: com.sun.xml.bind.api.AccessorException: java.lang.NullPointerException
at com.sun.xml.bind.v2.runtime.reflect.AdaptedAccessor.get(AdaptedAccessor.java:74)
at com.sun.xml.bind.v2.runtime.reflect.TransducedAccessor$CompositeTransducedAccessorImpl.writeLeafElement(TransducedAccessor.java:250)
at com.sun.xml.bind.v2.runtime.property.SingleElementLeafProperty.serializeBody(SingleElementLeafProperty.java:98)
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:332)
... 29 more
Caused by: java.lang.NullPointerException
at com.sun.xml.bind.v2.runtime.SwaRefAdapter.marshal(SwaRefAdapter.java:80)
at com.sun.xml.bind.v2.runtime.SwaRefAdapter.marshal(SwaRefAdapter.java:65)
at com.sun.xml.bind.v2.runtime.reflect.AdaptedAccessor.get(AdaptedAccessor.java:72)
... 32 more
第 80 行SwaRefAdapter
是return am.addSwaRefAttachment(data);
并且am
被分配了,所以如果存在的话,此时AttachmentMarshaller am = XMLSerializer.getInstance().attachmentMarshaller;
它似乎是空的。attachmentMarshaller
@XmlAttachmentRef
我是否需要进行不同的设置,或者以不同的方式使用 JAXB API 来处理附件?