通用html解析器,Java HTML/XML - 如何建立通用命名空間解析器

import java.util.Iterator;

import javax.xml.XMLConstants;

import javax.xml.namespace.NamespaceContext;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.xpath.XPath;

import javax.xml.xpath.XPathConstants;

import javax.xml.xpath.XPathExpression;

import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;

public class Main {

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

DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();

domFactory.setNamespaceAware(true);

DocumentBuilder builder = domFactory.newDocumentBuilder();

Document dDoc = builder.parse("c:\\file.xml");

XPath xPath = XPathFactory.newInstance().newXPath();

xPath.setNamespaceContext(new UniversalNamespaceResolver(dDoc));

String query = "//rss/channel/yweather:location/@city";

XPathExpression expr = xPath.compile(query);

Object result = expr.evaluate(dDoc, XPathConstants.STRING);

System.out.println(result);

}

}

class UniversalNamespaceResolver implements NamespaceContext {

private Document sourceDocument;

public UniversalNamespaceResolver(Document document) {

sourceDocument = document;

}

public String getNamespaceURI(String prefix) {

if (prefix.equals(XMLConstants.DEFAULT_NS_PREFIX))

return sourceDocument.lookupNamespaceURI(null);

else

return sourceDocument.lookupNamespaceURI(prefix);

}

public String getPrefix(String namespaceURI) {

return sourceDocument.lookupPrefix(namespaceURI);

}

public Iterator getPrefixes(String namespaceURI) {

return null;

}

}