Question

我有一个问题，即在xml结构中深入返回值。首先，这是xml代码：

<?xml version="1.0" encoding="UTF-8" ?> <log> <published>2014-03-28T15:28:36.646Z</published> <actor> <objectType>person</objectType> <id>e1b8948f-321e-78ca-d883-80500aae71b5</id> <displayName>anonymized</displayName> </actor> <verb>update</verb> <object> <objectType>concept</objectType> <id>a1ad6ace-c722-ffa9-f58e-b4169acdb4e3</id> <content>time</content> </object> <target> <objectType>conceptMap</objectType> <id>4b8f69e3-2914-3a1a-454e-f4c157734bd1</id> <displayName>my first concept map</displayName> </target> <generator> <objectType>application</objectType> <url>http://www.golabz.eu/content/go-lab-concept-mapper</url> <id>c9933ad6-dd4a-6f71-ce84-fb1676ea3aac</id> <displayName>ut.tools.conceptmapper</displayName> </generator> <provider> <objectType>ils</objectType> <url>http://graasp.epfl.ch/metawidget/1/b387b6f</url> <id>10548c30-72bd-0bb3-33d1-9c748266de45</id> <displayName>unnamed ils</displayName> </provider> </log>

我在Stackoverflow找到了一个方法来处理（How to retrieve element value of XML using Java?）：

protected String getString(String tagName, Element element) {
    NodeList list = element.getElementsByTagName(tagName);
    if (list != null && list.getLength() > 0) {
        NodeList subList = list.item(0).getChildNodes();

        if (subList != null && subList.getLength() > 0) {
            return subList.item(0).getNodeValue();
        }
    }

    return null;
}

我的问题是我不知道如何使用该方法获取特定ID（或其他元素的值）而不使用显式预定义方法（我想传递我在方法中寻找的ID） - 本身）。如果我使用getString("id", document.getDocumentElement)，它只返回“e1b8948f-321e-78ca-d883-80500aae71b5”-ID。如果我想获取<object>的子节点“a1ad6ace-c722-ffa9-f58e-b4169acdb4e3”该怎么办？

Answer 1

您可以使用XPath表达式。

XPathFactory xPathFactory = XPathFactory.newInstance();
XPath xPath = xPathFactory.newXPath();
XPathExpression xPathExpression = xPath.compile("//object/id");

// this should return one "id" node
NodeList idNodelist = (NodeList) xPathExpression.evaluate(document, XPathConstants.NODESET);
Node idNode = idNodelist.item(0);
System.out.println(idNode.getTextContent());

Java中的XML：从特定元素中获取值

1 个答案: