在 JAXB Marshalling 中，如何识别导致 JAXB Marshalling Exception 的子元素？

Question

我在编组我的 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是哪个子元素导致了这个异常？

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)

这是我用来编组 Jaxbelment 的代码：

JAXBElementdmlJAXBElement= SwapDMLGenerator.generateDML(event, 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，以debug模式运行程序，并在eclipse中设置条件断点。 见How to set a conditional break point in eclipse 条件是属性为空，因为您正在获取 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。

Answer 2

使用 Eclipse IDE，可以调试一些第 3 方代码，例如 Sun 的 JAXB 实现。

在 Eclipse 中，试试这两个块：

启用第 3 方调试支持

Search for class AttributeProperty inside your classpath entry for JRE System Library
In Outline tab, expand class file and respective class inside this
Right-Click on target method (in this case: AttributeProperty.getIdValue)
Click on: Toggle Method Breakpoint

检查哪些字段有问题：

1. 启用调试选项卡和变量选项卡
2. 与其他调试过程一样，在调试模式下开始测试
3. 当程序达到相关断点时，检查变量选项卡“this”和“arg0”的引用。这些引用包含有关当前节点和混搭对象的信息

此时，您已准备好分析和调试上下文。

我正在处理相同的 JAXB/IDREF 问题，但还没有任何解决方案。我正在检查它。

这个问题你解决了吗？

最好的问候，

过去