Java中带有命名空间的XPath

2022-01-14 00:00:00 xpath namespaces java

我想获取标签之间的所有内容，但由于 urn: 命名空间，我不知道该怎么做.

I would like to get all the content in between the tags but I do not know how to do this because of the urn: namespace.

<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>

有什么想法吗?

推荐答案

  1. 简答:使用 XPath local-name().像这样: xPathFactory.newXPath().compile("//*[local-name()='requestURL']/text()"); 将返回 /CAMERA/Streaming/状态
  2. 或者您可以实现一个 NamespaceContext 来映射命名空间名称和 URI，并在查询之前将其设置在 XPath 对象上.
  3. 看看这篇博客文章，更新:文章已下架，您可以在webarchive
  1. Short answer: use XPath local-name(). Like this: xPathFactory.newXPath().compile("//*[local-name()='requestURL']/text()"); will return /CAMERA/Streaming/status
  2. Or you can implement a NamespaceContext that maps namespaces names and URIs and set it on the XPath object before querying.
  3. Take a look at this blog article, Update: the article is down, you can see it on webarchive

解决方案 1 示例:

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

解决方案 2 示例:

// 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

这是一个完整的例子，它正确地检索了元素:

This is a complete example, it correctly retrieve the element:

String xml = "<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>";
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() + ")");
}

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