无法使用 DOM 解析器读取带有命名空间前缀的 xml

2022-01-10 00:00:00 xml xml-parsing dom java

这是输入 XML:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
   <SOAP-ENV:Header/>
   <SOAP-ENV:Body>
      <ns2:SendResponse xmlns:ns2="http://mycompany.com/schema/">
         <ns2:SendResult>
            <ns2:Token>A00179-02</ns2:Token>
         </ns2:SendResult>
      </ns2:SendResponse>
   </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

这是我用来读取 XML 的代码(变量 xmlString 包含上面的 XML):

This the code that I'm using to read the XML (Variable xmlString contains the XML above):

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setNamespaceAware(true);
DocumentBuilder db = dbf.newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader(xmlString));
Document doc = db.parse(is);

System.out.println("Element :" + doc.getElementsByTagName("Token").item(0));
System.out.println("Element :" + doc.getElementsByTagName("ns2:Token").item(0));

输出:

Element :null
Element :[ns2:Token: null]

如果我使用ns2:Token"作为标签名称，我可以读取元素，但我不想在代码中使用前缀，因为我不确定它是否相同或将来改变.有什么方法可以读取 xml 元素而无需在标签名称中硬编码命名空间?

I'm able to read the element if I use "ns2:Token" as the tag name, but I don't want to use the prefix in my code as I'm not sure if it'll be the same or change in the future. Is there any way to read the xml element without hard-coding the namespace in the tag name?

推荐答案

W3C dom 命名空间元素的方法:

The W3C dom method for namespaced elements: 

getElementsByTagNameNS

NodeList getElementsByTagNameNS(String namespaceURI,
                                String localName)

    Returns a NodeList of all the Elements with a given local name and namespace URI in document order.

    Parameters:
        namespaceURI - The namespace URI of the elements to match on. The special value "*" matches all namespaces.
        localName - The local name of the elements to match on. The special value "*" matches all local names. 
    Returns:
        A new NodeList object containing all the matched Elements.
    Since:
        DOM Level 2

IIRC 早期版本的 W3C DOM 对命名空间的支持很差，所以我不使用它.但是，如果您将上述内容与完整的 namespaceURI http://schemas.xmlsoap.org/soap/envelope/ 一起使用，它应该可以工作.前缀并不重要——它在使用它的文档之外没有永久性.

IIRC earlier version of the W3C DOM had poor support for namespaces so I don't use it. However if you use the above with the full namespaceURI http://schemas.xmlsoap.org/soap/envelope/ it should work. The prefix is unimportant - it has no permanency outside the document it is used in.

那就试试吧:

System.out.println("Element :" + doc.getElementsByTagNameNS(
        "http://schemas.xmlsoap.org/soap/envelope/", "Token").item(0));

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