Java 如何使用JAXB封送注释为@XmlAttachmentRef的数据处理程序？

我正试图用JAXB（2.1.12）封送一个具有

DataHandler

字段的对象。对于流式传输支持，

DataHandler

用@

XmlAttachmentRef

注释。web服务上的序列化和流式处理（JBoss上的Metro）工作得很好，但使用JAXB的简单编组却不行

下面是一个简单的示例：

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());
    }
}

运行此测试将生成以下堆栈跟踪：

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

SwaRefAdapter

中的第80行是

返回am.addSwaRefAttachment（数据）和
am
分配了
AttachmentMarshaller am=XMLSerializer.getInstance（）.AttachmentMarshaller
因此，如果存在
@XmlAttachmentRef
，则此时似乎
attachmentMarshaller
为空

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？
在JAX-WS环境之外使用JAXB时，JAXB实现应该默认为内联，XML文档中的二进制内容为base64Binary

这似乎是JAXB（JDK/JRE中包含的RI）的Metro实现中的一个bug。如果您使用另一个JAXB实现，例如，这将正常工作。要使用EclipseLink MOXy，请将EclipseLink.jar（）添加到类路径中，并在模型类中添加一个jaxb.properties文件，其中包含以下内容：

javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory

JAX-WS注册AttachmentMarshaller和AttachmentUnmarshaller以处理JAXB模型中的二进制内容。如果需要，可以在使用JAXB standalone时指定自己的