如何在Java中使用XPath访问OWL文档？

问题描述

我正在以XML文件的形式提供OWL文档。我想从这个文档中提取元素。我的代码适用于简单的XML文档，但它不适用于OWL XML文档。

I am having an OWL document in the form of an XML file. I want to extract elements from this document. My code works for simple XML documents, but it does not work with OWL XML documents.

我实际上是想获得这个元素： / rdf ：RDF / owl：Ontology / rdfs：label ，我这样做了：

I was actually looking to get this element: /rdf:RDF/owl:Ontology/rdfs:label, for which I did this:

 DocumentBuilder builder = builderfactory.newDocumentBuilder();
    Document xmlDocument = builder.parse(
            new File(XpathMain.class.getResource("person.xml").getFile()));

    XPathFactory factory = javax.xml.xpath.XPathFactory.newInstance();
    XPath xPath = factory.newXPath();
    XPathExpression xPathExpression = xPath.compile("/rdf:RDF/owl:Ontology/rdfs:label/text()");
    String nameOfTheBook = xPathExpression.evaluate(xmlDocument,XPathConstants.STRING).toString();

我还尝试仅提取 rdfs：label 元素这样：

I also tried extracting only the rdfs:label element this way:

 XPathExpression xPathExpression = xPath.compile("//rdfs:label");        
 NodeList nodes = (NodeList) xPathExpression.evaluate(xmlDocument, XPathConstants.NODESET);

但此节点列表为空。

请告诉我出错的地方。我正在使用Java XPath API。

Please let me know where I am going wrong. I am using Java XPath API.

推荐答案

因为xpath不知道您正在使用的命名空间。
尝试使用：

as xpath does not know the namespaces you are using.try using:

"/*[local-name()='RDF']/*[local-name()='Ontology']/*[local-name()='label']/text()"

本地名称将忽略命名空间并将起作用（对于它找到的第一个实例）

local name will ignore the namespaces and will work (for the first instance of this that it finds)

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