如何在 Java 中使用 XPath 访问 OWL 文档? [英] How to access OWL documents using XPath in Java?

问题描述

我有一个 XML 文件形式的 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.

我实际上是想得到这个元素:/rdf:RDF/owl:Ontology/rdfs:label，为此我做了这个:

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();

我也尝试以这种方式仅提取 rdfs:label 元素:

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);

但是这个节点列表是空的.

But this nodelist is empty.

请让我知道我哪里出错了.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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