Java中具有名称空间的XPath

Question

我想获取标记之间的所有内容，但是由于urn：名称空间，我不知道该怎么做。

<urn:ResponseStatus version="1.0" xmlns:urn="urn:camera-org">

<urn:requestURL>/CAMERA/Streaming/status</urn:requestURL>
<urn:statusCode>4</urn:statusCode>
<urn:statusString>Invalid Operation</urn:statusString>
<urn:id>0</urn:id>

</urn:ResponseStatus>

有任何想法吗？

Answer 1

1. 简短的答案：使用XPath local-name()。这样：xPathFactory.newXPath().compile("//*[local-name()='requestURL']/text()");将返回/CAMERA/Streaming/status
2. 或者，您可以实现一个NamespaceContext映射名称空间名称和URI的，并在查询之前在XPath对象上对其进行设置。
3. 看一下这篇博客文章， 更新： 该文章已结束，您可以在webarchive上看到它

解决方案1样本：

XPath xpath = XPathFactory.newInstance().newXPath();
String responseStatus = xpath.evaluate("//*[local-name()='ResponseStatus']/text()", document);
System.out.println("-> " + responseStatus);

解决方案2样本：

// load the Document
Document document = ...;
NamespaceContext ctx = new NamespaceContext() {
    public String getNamespaceURI(String prefix) {
        return prefix.equals("urn") ? "urn:camera-org" : null; 
    }
    public Iterator getPrefixes(String val) {
        return null;
    }
    public String getPrefix(String uri) {
        return null;
    }
};
XPath xpath = XPathFactory.newInstance().newXPath();
xpath.setNamespaceContext(ctx);
String responseStatus = xpath.evaluate("//urn:ResponseStatus/text()", document);
System.out.println("-> " + responseStatus);

编辑

这是一个完整的示例，它可以正确检索元素：

String xml = "<urn:ResponseStatus version=\"1.0\" xmlns:urn=\"urn:camera-org\">\r\n" + //
        "\r\n" + //
        "<urn:requestURL>/CAMERA/Streaming/status</urn:requestURL>\r\n" + //
        "<urn:statusCode>4</urn:statusCode>\r\n" + //
        "<urn:statusString>Invalid Operation</urn:statusString>\r\n" + //
        "<urn:id>0</urn:id>\r\n" + //
        "\r\n" + //
        "</urn:ResponseStatus>";
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true);
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(new java.io.ByteArrayInputStream(xml.getBytes()));
XPath xpath = XPathFactory.newInstance().newXPath();
xpath.setNamespaceContext(new NamespaceContext() {
    public String getNamespaceURI(String prefix) {
        return prefix.equals("urn") ? "urn:camera-org" : null;
    }

    public Iterator<?> getPrefixes(String val) {
        return null;
    }

    public String getPrefix(String uri) {
        return null;
    }
});
XPathExpression expr = xpath.compile("//urn:ResponseStatus");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
    Node currentItem = nodes.item(i);
    System.out.println("found node -> " + currentItem.getLocalName() + " (namespace: " + currentItem.getNamespaceURI() + ")");
}