java - 在 JAXB Marshalling 中，如何识别哪个子元素导致了 JAXB Marshalling Exception？

Question

我在编码我的 JAXBElement 时遇到了这个异常，它有几个子元素。我如何弄清楚如何查明导致此异常的子元素？

java.lang.NullPointerException
    at com.sun.xml.bind.v2.runtime.property.AttributeProperty.getIdValue(AttributeProperty.java:128)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.getId(ClassBeanInfoImpl.java:320)
    at com.sun.xml.bind.v2.runtime.reflect.TransducedAccessor$IDREFTransducedAccessorImpl.print(TransducedAccessor.java:290)
    at com.sun.xml.bind.v2.runtime.reflect.TransducedAccessor$IDREFTransducedAccessorImpl.print(TransducedAccessor.java:271)
    at com.sun.xml.bind.v2.runtime.property.AttributeProperty.serializeAttributes(AttributeProperty.java:101)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeAttributes(ClassBeanInfoImpl.java:375)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:689)
    at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.serializeBody(SingleElementNodeProperty.java:158)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.serializeBody(SingleElementNodeProperty.java:158)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.ArrayElementNodeProperty.serializeItem(ArrayElementNodeProperty.java:69)
    at com.sun.xml.bind.v2.runtime.property.ArrayElementProperty.serializeListBody(ArrayElementProperty.java:172)
    at com.sun.xml.bind.v2.runtime.property.ArrayERProperty.serializeBody(ArrayERProperty.java:159)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.serializeBody(SingleElementNodeProperty.java:158)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl$1.serializeBody(ElementBeanInfoImpl.java:161)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl$1.serializeBody(ElementBeanInfoImpl.java:131)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeBody(ElementBeanInfoImpl.java:333)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeRoot(ElementBeanInfoImpl.java:340)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeRoot(ElementBeanInfoImpl.java:76)
    at com.sun.xml.bind.v2.runtime.property.SingleReferenceNodeProperty.serializeBody(SingleReferenceNodeProperty.java:115)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.serializeBody(SingleElementNodeProperty.java:158)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.serializeBody(SingleElementNodeProperty.java:158)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.ArrayElementNodeProperty.serializeItem(ArrayElementNodeProperty.java:69)
    at com.sun.xml.bind.v2.runtime.property.ArrayElementProperty.serializeListBody(ArrayElementProperty.java:172)
    at com.sun.xml.bind.v2.runtime.property.ArrayERProperty.serializeBody(ArrayERProperty.java:159)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl$1.serializeBody(ElementBeanInfoImpl.java:156)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl$1.serializeBody(ElementBeanInfoImpl.java:131)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeBody(ElementBeanInfoImpl.java:333)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeRoot(ElementBeanInfoImpl.java:340)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeRoot(ElementBeanInfoImpl.java:76)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsRoot(XMLSerializer.java:494)
    at com.sun.xml.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:323)
    at com.sun.xml.bind.v2.runtime.MarshallerImpl.marshal(MarshallerImpl.java:251)
    at javax.xml.bind.helpers.AbstractMarshallerImpl.marshal(AbstractMarshallerImpl.java:75)
    at com.tdsecurities.fxdev.doddfranktdmladapter.SwapTDMLGeneratorJunitTest.testHello(SwapTDMLGeneratorJunitTest.java:113)

这是我用来编码 Jaxbelment 的代码:

JAXBElementdmlJAXBElement= SwapDMLGenerator.generateDML(事件，leg1ordMm，leg2ordMm， leg1OrdCs, leg2OrdCs);

JAXBContext jaxbContext_m = JAXBContext.newInstance(DmlWrapper.class);
Marshaller marshaller = jaxbContext_m.createMarshaller();
//marshaller.setProperty(Marshaller.JAXB_SCHEMA_LOCATION, "");
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);        
String  outFileName= String.format("dml-%d-ordm_deallnum-%s.xml",System.currentTimeMillis(), .getDealNumber());
File fout= new File(destDir, outFileName);
FileOutputStream fos= new FileOutputStream(fout);
marshaller.marshal(dmlJAXBElement, fos);
fos.close();

Answer 1

我能想到的一种方法是在项目中包含 JAXB 的源代码，在 Debug模式下运行程序并在 eclipse 中放置一个条件断点。参见 How to set a conditional break point in eclipse条件是该属性为空，因为您得到的是 NPE。然后，当执行在该点停止时，您可以检查适当的变量。

其他替代方法是查看增加日志级别是否可以为您提供更多信息。