如何使用java获取xml节点的属性值

java xml xml-attribute xmlnode

2022-09-02 03:13:53

我有一个xml，看起来像这样：

{ <xml><ep><source type="xml">...</source><source type="text">..</source></ep></xml>}

在这里，我想检索“源类型”的值，其中类型s是一个属性。

我试过这样，但它不起作用：

 DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
                try {
                    DocumentBuilder builder = domFactory.newDocumentBuilder();
                    Document dDoc = builder.parse("D:/workspace1/ereader/src/main/webapp/configurations/config.xml");
                    System.out.println(dDoc);
                    XPath xPath = XPathFactory.newInstance().newXPath();
                    Node node = (Node) xPath.evaluate("//xml/source/@type/text()", dDoc, XPathConstants.NODE);
                    System.out.println(node);
                } catch (Exception e) {
                    e.printStackTrace();

我也试过这个：

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            InputSource is = new InputSource(new StringReader("config.xml"));
            Document doc = builder.parse(is);

            NodeList nodeList = doc.getElementsByTagName("source");

            for (int i = 0; i < nodeList.getLength(); i++) {                
                Node node = nodeList.item(i);

                if (node.hasAttributes()) {
                    Attr attr = (Attr) node.getAttributes().getNamedItem("type");
                    if (attr != null) {
                        String attribute= attr.getValue();                      
                        System.out.println("attribute: " + attribute);                      
                    }
                }
            }

请帮帮我！！

提前致谢瓦尔沙

答案 1

由于您的问题更通用，因此请尝试使用Java中可用的XML解析器来实现它。如果你需要它特定于解析器，请在此处更新你的代码，你已经尝试过

<?xml version="1.0" encoding="UTF-8"?>
<ep>
    <source type="xml">TEST</source>
    <source type="text"></source>
</ep>

DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse("uri to xmlfile");
XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();
XPathExpression expr = xpath.compile("//ep/source[@type]");
NodeList nl = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);

for (int i = 0; i < nl.getLength(); i++)
{
    Node currentItem = nl.item(i);
    String key = currentItem.getAttributes().getNamedItem("type").getNodeValue();
    System.out.println(key);
}

答案 2

试试这样的东西：

    DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
    Document dDoc = builder.parse("d://utf8test.xml");

    XPath xPath = XPathFactory.newInstance().newXPath();
    NodeList nodes = (NodeList) xPath.evaluate("//xml/ep/source/@type", dDoc, XPathConstants.NODESET);
    for (int i = 0; i < nodes.getLength(); i++) {
        Node node = nodes.item(i);
        System.out.println(node.getTextContent());
    }

请注意这些变化：

我们要求一个节点集（XPathConstants.NODESET），而不仅仅是单个节点。
xpath 现在是 //xml/ep/source/@type 而不是 //xml/source/@type/text（）

PS：你能在你的问题中添加标签java吗？谢谢。