使用带有 Java 类命名空间的 xpath [英] using xpath with namespace from a java class

问题描述

我正在尝试使用 XPATH 解析带有命名空间的 xml 文档.我已经阅读了它应该如何完成.我也实现了 NamespaceContext.但是，我仍然没有得到这些值.我想我错过了一些简单的东西.

I am trying to parse an xml document with namespace using XPATH. I have read how it is supposed to be done. I have implemented NamespaceContext as well. But, I still am not getting the values. I think I am missing something simple.

我的 xml 输入是

<?xml version="1.0" encoding="UTF-8"?>
<ns1:customer xmlns:ns1="http://test/ns1">
    <ns1:name>john</ns1:name>
</ns1:customer>

我的主文件是 TestXMLPath

My Main file is TestXMLPath

public static void main(String[] args) throws Exception {

  String myInputXML = "src/testxmlpath/input-with-namespace.xml";
  DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();        

  String expression ="/ns1:customer/ns1:name";

  Document document = db.parse(new File(myInputXML)) ;
  XPath xpath = XPathFactory.newInstance().newXPath();
  xpath.setNamespaceContext(new SimpleNamespaceContextImpl());
  String value = xpath.evaluate(expression,document);
  System.out.println("value" + value);
}

我的 NamespaceContext 实现是

my NamespaceContext implementation is

public class SimpleNamespaceContextImpl implements NamespaceContext {

@Override
public String getNamespaceURI(String prefix) {
    System.out.println("getNameSpace for prefix "+prefix);        
    if (prefix == null) {            
        throw new NullPointerException("Null prefix");
    } else if ("ns1".equals(prefix)) {            
        return "http://test/ns1";
    } else if ("xml".equals(prefix)) {            
        return XMLConstants.XML_NS_URI;
    } else {            
        return XMLConstants.XML_NS_URI;
    }
}

@Override
public String getPrefix(String namespaceURI) {        
    return "ns1";
}

@Override
public Iterator getPrefixes(String namespaceURI) {
    return null;
}
}

我在调用方法时打印出来.这是输出.

I print out when a method gets called. Here is the output.

getNameSpace for prefix ns1
getNameSpace for prefix ns1
value
BUILD SUCCESSFUL

我不明白，为什么它不起作用??

I can't understand, why won't it work ??

任何帮助将不胜感激.

谢谢

推荐答案

对我来说效果很好.输出:

Works fine for me. Output:

getNameSpace for prefix ns1
getNameSpace for prefix ns1
valuejohn

您确定要加载正确的文档吗?我正在使用 Xerces 来构建文档并使用 Saxon 来评估 XPath.相关类的转储:

Are you sure you're loading the right document? I'm using Xerces to build the document and Saxon to evaluate the XPath. A dump of the relevant classes:

class com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl
class com.sun.org.apache.xerces.internal.dom.DeferredDocumentImpl
class net.sf.saxon.xpath.XPathFactoryImpl

这篇关于使用带有 Java 类命名空间的 xpath的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！