Java XPath：获取与查询匹配的所有元素

Question

我想在这个 XML 文件（节选如下）上进行 XPath 查询：

<?xml version="1.0" encoding="UTF-8"?>
<!-- MetaDataAPI generated on: Friday, May 25, 2007 3:26:31 PM CEST -->
<Component xmlns="http://xml.sap.com/2002/10/metamodel/webdynpro" xmlns:IDX="urn:sap.com:WebDynpro.Component:2.0" mmRelease="6.30" mmVersion="2.0" mmTimestamp="1180099591892" name="MassimaleContr" package="com.bi.massimalecontr" masterLanguage="it">
...
    <Component.UsedModels>
        <Core.Reference package="com.test.test" name="MasterModel" type="Model"/>
        <Core.Reference package="com.test.massimalecontr" name="MassimaleModel" type="Model"/>
        <Core.Reference package="com.test.test" name="TravelModel" type="Model"/>
    </Component.UsedModels>
...

我正在使用以下代码片段：

DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true);
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document document = builder.parse(new File("E:\\Test branch\\test.wdcomponent"));
XPathFactory factory = XPathFactory.newInstance();
XPath xpath = factory.newXPath();

xpath.setNamespaceContext(new NamespaceContext() {
...(omitted)

System.out.println(xpath.evaluate(
    "//d:Component/d:Component.UsedModels/d:Core.Reference/@name", 
    document));

我期望得到什么：

MasterModel
MassimaleModel
TravelModel

我得到的是:

MasterModel

看起来只返回了第一个元素。我该如何获取所有与我的查询匹配的出现次数？

- Pietro M.

Answer 1

你将得到一个类型为NodeList的项目

XPathExpression expr = xpath.compile("//Core.Reference");
NodeList list= (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
for (int i = 0; i < list.getLength(); i++) {
    Node node = list.item(i);
    System.out.println(node.getTextContent());
    // work with node

- Christian Kuetbach

Answer 2

请参见如何在Java中使用XPath读取XML

根据该示例，如果您首先编译XPath表达式，然后执行它，并指定您需要一个NodeSet返回，那么您应该得到所需的结果。

- Jon Payne