xpath之EclipseLink Moxy unmarshall 和 getValueByXPath 给出 null

我使用下面的代码来解码​​并通过 Xpath 查询解码的对象。
我能够在解码后获取对象，但是在通过 XPath 查询时，该值变为 null。

我需要指定任何 NameSpaceResolver 吗？

如果您正在寻找任何进一步的信息，请告诉我。

我的代码:

         JAXBContext jaxbContext = (JAXBContext) JAXBContextFactory.createContext(new Class[] {Transaction.class}, null); 
         Unmarshaller unmarshaller = jaxbContext.createUnmarshaller(); 
         StreamSource streamSource= new StreamSource(new StringReader(transactionXML)); 
         transaction = unmarshaller.unmarshal(streamSource, Transaction.class).getValue(); 
         String displayValue = jaxbContext.getValueByXPath(transaction, xPath, null, String.class); 

我的 XML:

         <Transaction xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"                          xmlns:xsd="http://www.w3.org/2001/XMLSchema" > 
         <SendingCustomer firstName="test"> 
 
         </SendingCustomer> 
         </Transaction> 

请您参考如下方法:

由于您的示例中没有命名空间，因此您无需担心使用 NamespaceResolver .您没有提供您遇到问题的 XPath，所以我只在下面的示例中选择了一个。

JAVA模型

交易

import javax.xml.bind.annotation.*; 
 
@XmlRootElement(name="Transaction") 
public class Transaction { 
 
    @XmlElement(name="SendingCustomer") 
    private Customer sendingCustomer; 
 
} 

客户

import javax.xml.bind.annotation.XmlAttribute; 
 
public class Customer { 
 
    @XmlAttribute 
    private String firstName; 
 
    @XmlAttribute 
    private String lastNameDecrypted; 
 
    @XmlAttribute(name="OnWUTrustList") 
    private boolean onWUTrustList; 
 
    @XmlAttribute(name="WUTrustListType") 
    private String wuTrustListType; 
 
} 

演示代码

输入.xml

<Transaction xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:xsd="http://www.w3.org/2001/XMLSchema"> 
    <SendingCustomer firstName="test" lastNameDecrypted="SMITH" 
        OnWUTrustList="false" WUTrustListType="NONE"> 
 
    </SendingCustomer> 
</Transaction> 

演示

import javax.xml.bind.Unmarshaller; 
import javax.xml.transform.stream.StreamSource; 
import org.eclipse.persistence.jaxb.JAXBContext; 
import org.eclipse.persistence.jaxb.JAXBContextFactory; 
 
public class Demo { 
 
    public static void main(String[] args) throws Exception { 
        JAXBContext jaxbContext = (JAXBContext) JAXBContextFactory.createContext(new Class[] {Transaction.class}, null); 
        Unmarshaller unmarshaller = jaxbContext.createUnmarshaller(); 
        StreamSource streamSource= new StreamSource("src/forum17687460/input.xml"); 
        Transaction transaction = unmarshaller.unmarshal(streamSource, Transaction.class).getValue(); 
        String displayValue = jaxbContext.getValueByXPath(transaction, "SendingCustomer/@firstName", null, String.class); 
        System.out.println(displayValue); 
    } 
 
} 

输出

test