Java中带有命名空间的XPath

Posted 2023-02-23

【中文标题】Java中带有命名空间的XPath

【英文标题】：XPath with namespace in Java

【发布时间】：2012-11-22 01:30:57

【问题描述】：

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。

<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？

【问题讨论】：

你用的是什么库？您是否尝试在查询前加上 urn: ？

使用 javax.xml.xpath.XPath;我试过 urn: 但这没有帮助。

【参考方案1】：

简答：使用 XPath local-name()。像这样：xPathFactory.newXPath().compile("//*[local-name()='requestURL']/text()"); 将返回 /CAMERA/Streaming/status 或者您可以实现一个 NamespaceContext，它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。 看看这个blog article，更新：文章下架了，大家可以在webarchive看到

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：

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() + ")");

【讨论】：

好答案！ （如果代码被缩进并且示例 XML 没有被他自己的服务器吃掉，那篇博文会更有用。哦，好吧，最后仍然是一个有用的列表。）

非常感谢！我使用这个逻辑解析了一个巨大的复杂 xml 文件，它对我有用。

getNamespaceURI 应该返回 XMLConstants.NULL_NS_URI（这是一个空字符串）而不是 null 当它不匹配任何注册的前缀。

blog.davber.com 网站现在只返回内部服务器错误。

全部：我通过 webarchive 更新了第 3 点中原始博客文章的链接的答案

【参考方案2】：

XML xpath 与 Namespace

简单的 XML

String namespaceXML = "<?xml version='1.0' ?><information><person id='1'><name>Deep</name><age>34</age><gender>Male</gender></person>  <person id='2'><name>Kumar</name><age>24</age><gender>Male</gender></person> <person id='3'><name>Deepali</name><age>19</age><gender>Female</gender></person><!-- more persons... --></information>";
String jsonString = "";
String expression = "//information";

名称空间 XML

String namespaceXML = "<soap:Envelope xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\"><soap:Body><m:NumberToDollarsResponse xmlns:m=\"http://www.dataaccess.com/webservicesserver/\"><m:NumberToDollarsResult>nine hundred and ninety nine dollars</m:NumberToDollarsResult></m:NumberToDollarsResponse></soap:Body></soap:Envelope>";
String jsonString = "'soap':'http://schemas.xmlsoap.org/soap/envelope/', 'm':'http://www.dataaccess.com/webservicesserver/'";
String expression = "//m:NumberToDollarsResponse/m:NumberToDollarsResult/text()";

将命名空间 xml 文件作为字符串提供给asscerionXpath(namespaceXML, jsonString, expression) 方法并以文本/节点的形式获取结果。

文本（）：nine hundred and ninety nine dollars

节点： <m:NumberToDollarsResult xmlns:m="http://www.dataaccess.com/webservicesserver/"> nine hundred and ninety nine dollars </m:NumberToDollarsResult>

public static String asscerionXpath(String namespaceXML, String jsonString, String expression)
    if(namespaceXML.indexOf("><") > -1) namespaceXML = namespaceXML.replace("><", ">\r\n<");
    if(jsonString.indexOf("'") > -1)    jsonString = jsonString.replace("'", "\"");

    System.out.println("namespaceXML : \n"+namespaceXML);
    System.out.println("nsmespaces : \n"+jsonString);

    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    factory.setValidating(false);
    factory.setNamespaceAware(true);
    factory.setIgnoringComments(true);
    factory.setIgnoringElementContentWhitespace(true);
    try 
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document source = builder.parse( string2Source(namespaceXML) );
        XPath xpath = XPathFactory.newInstance().newXPath();

        addNameSpaces(jsonString, xpath);
        // An XPath expression is not thread-safe. Make sure it is accessible by only one Thread.
        XPathExpression expr = xpath.compile(expression);

        // The NodeList interface provides the abstraction of an ordered collection of nodes,
        NodeList nodes = (org.w3c.dom.NodeList) expr.evaluate(source, XPathConstants.NODESET);;
        Node tree_base = nodes.item(0);
        return document2String(tree_base);
     catch (UnsupportedEncodingException e) 
        e.printStackTrace();
     catch (SAXException e) 
        e.printStackTrace();
     catch (IOException e) 
        e.printStackTrace();
     catch (ParserConfigurationException e) 
        e.printStackTrace();
     catch (XPathExpressionException e) 
        System.out.println("If the expression cannot be evaluated.");
    
    return "";

static InputSource string2Source( String str ) 
    InputSource inputSource = new InputSource( new StringReader( str ) );
    return inputSource;

static void addNameSpaces(String jsonString, XPath xpath) 
    JSONParser parser = new JSONParser();
    try 
        JSONObject namespaces = (JSONObject) parser.parse(jsonString);

        if (namespaces.size() > 0) 
            final JSONObject declaredPrefix = namespaces; // To access in Inner-class.
            NamespaceContext nameSpace = new NamespaceContext() 
                // To get all prefixes bound to a Namespace URI in the current scope, XPath 1.0 specification
                // --> "no prefix means no namespace"
                public String getNamespaceURI(String prefix) 
                    Iterator<?> key = declaredPrefix.keySet().iterator();
                    System.out.println("Keys : "+key.toString());
                    while (key.hasNext()) 
                        String name = key.next().toString();
                        if (prefix.equals(name)) 
                            System.out.println(declaredPrefix.get(name));
                            return declaredPrefix.get(name).toString();
                        
                    
                    return "";
                
                public Iterator<?> getPrefixes(String val) 
                    return null;
                
                public String getPrefix(String uri) 
                    return null;
                
            ;// Inner class.

            xpath.setNamespaceContext( nameSpace );
        

     catch ( org.json.simple.parser.ParseException e) 
        e.printStackTrace();