Question

查看示例，看起来我应该能够使用moxy＆＃39; getValueByXPath来访问umarshalled xml对象的子元素。但相反，我总是返回null。可以访问根对象上的属性。

当我在this question's answer中运行示例时，它运行正常：/这是我正在做的事情：

的xml：

<?xml version="1.0" encoding="UTF-8"?>
<OTA_HotelInvCountNotifRQ xmlns="http://www.opentravel.org/OTA/2003/05" AltLangID="alt lang id fnord">
   <Inventories AreaID="areaID_fnord">
      <Inventory>
         <UniqueID ID="inventory unique id fnord"/>
      </Inventory>
   </Inventories>
</OTA_HotelInvCountNotifRQ>

的java：

import org.eclipse.persistence.jaxb.JAXBContext;
import org.eclipse.persistence.jaxb.JAXBContextFactory;

....

OTAHotelInvCountNotifRQ rq = ...
JAXBContext ctx = (JAXBContext) JAXBContextFactory.createContext("org.opentravel.ota._2003._05", Main.class.getClassLoader());
String altLangId = ctx.getValueByXPath(rq, "@AltLangID", null, String.class);
assertThat("rq's altlang attr", altLangId, is(ALT_LANG_ID));

InvCountType inventories = ctx.getValueByXPath(rq, "Inventories", null, InvCountType.class);
assertThat("inventories", inventories, is(not(nullValue())));

我有一个可运行的simple self-contained complete example（mvn exec:java）。我无法更改OTA类（我是从xsd生成它们并为方便起见而包含它们）。

为什么这会返回null而不是预期的对象？

Answer 1

由于您的XML文档是名称空间限定的，因此您需要命名空间限定您的XPath。然后，您需要使用NamespaceResolver的实例为命名空间映射配对提供前缀。这将作为参数传递给getValueByXPath方法。

import java.io.File;
import javax.xml.bind.*;
import org.eclipse.persistence.jaxb.JAXBHelper;
import org.eclipse.persistence.oxm.NamespaceResolver;
import org.opentravel.ota._2003._05.*;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance("org.opentravel.ota._2003._05", ObjectFactory.class.getClassLoader(), null);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        File xml = new File("input.xml");
        OTAHotelInvCountNotifRQ rq = (OTAHotelInvCountNotifRQ) unmarshaller.unmarshal(xml);

        NamespaceResolver nsResolver = new NamespaceResolver();
        nsResolver.put("ns", "http://www.opentravel.org/OTA/2003/05");

        InvCountType inventories = JAXBHelper.getJAXBContext(jc).getValueByXPath(rq, "ns:Inventories", nsResolver, InvCountType.class);
        System.out.println(inventories);
    }

}

除了根元素之外，Moxy的getValueByXPath都返回null

1 个答案: