XPathAPIpublic class XPathAPI extends Object | The methods in this class are convenience methods into the
low-level XPath API.
These functions tend to be a little slow, since a number of objects must be
created for each evaluation. A faster way is to precompile the
XPaths using the low-level API, and then just use the XPaths
over and over.
NOTE: In particular, each call to this method will create a new
XPathContext, a new DTMManager... and thus a new DTM. That's very
safe, since it guarantees that you're always processing against a
fully up-to-date view of your document. But it's also portentially
very expensive, since you're rebuilding the DTM every time. You should
consider using an instance of CachedXPathAPI rather than these static
methods. |
| Methods Summary |
|---|
| public static com.sun.org.apache.xpath.internal.objects.XObject | eval(org.w3c.dom.Node contextNode, java.lang.String str)Evaluate XPath string to an XObject. Using this method,
XPath namespace prefixes will be resolved from the namespaceNode.
return eval(contextNode, str, contextNode);
| | public static com.sun.org.apache.xpath.internal.objects.XObject | eval(org.w3c.dom.Node contextNode, java.lang.String str, org.w3c.dom.Node namespaceNode)Evaluate XPath string to an XObject.
XPath namespace prefixes are resolved from the namespaceNode.
The implementation of this is a little slow, since it creates
a number of objects each time it is called. This could be optimized
to keep the same objects around, but then thread-safety issues would arise.
// Since we don't have a XML Parser involved here, install some default support
// for things like namespaces, etc.
// (Changed from: XPathContext xpathSupport = new XPathContext();
// because XPathContext is weak in a number of areas... perhaps
// XPathContext should be done away with.)
XPathContext xpathSupport = new XPathContext();
// Create an object to resolve namespace prefixes.
// XPath namespaces are resolved from the input context node's document element
// if it is a root node, or else the current context node (for lack of a better
// resolution space, given the simplicity of this sample code).
PrefixResolverDefault prefixResolver = new PrefixResolverDefault(
(namespaceNode.getNodeType() == Node.DOCUMENT_NODE)
? ((Document) namespaceNode).getDocumentElement() : namespaceNode);
// Create the XPath object.
XPath xpath = new XPath(str, null, prefixResolver, XPath.SELECT, null);
// Execute the XPath, and have it return the result
// return xpath.execute(xpathSupport, contextNode, prefixResolver);
int ctxtNode = xpathSupport.getDTMHandleFromNode(contextNode);
return xpath.execute(xpathSupport, ctxtNode, prefixResolver);
| | public static com.sun.org.apache.xpath.internal.objects.XObject | eval(org.w3c.dom.Node contextNode, java.lang.String str, com.sun.org.apache.xml.internal.utils.PrefixResolver prefixResolver)Evaluate XPath string to an XObject.
XPath namespace prefixes are resolved from the namespaceNode.
The implementation of this is a little slow, since it creates
a number of objects each time it is called. This could be optimized
to keep the same objects around, but then thread-safety issues would arise.
// Since we don't have a XML Parser involved here, install some default support
// for things like namespaces, etc.
// (Changed from: XPathContext xpathSupport = new XPathContext();
// because XPathContext is weak in a number of areas... perhaps
// XPathContext should be done away with.)
// Create the XPath object.
XPath xpath = new XPath(str, null, prefixResolver, XPath.SELECT, null);
// Execute the XPath, and have it return the result
XPathContext xpathSupport = new XPathContext();
int ctxtNode = xpathSupport.getDTMHandleFromNode(contextNode);
return xpath.execute(xpathSupport, ctxtNode, prefixResolver);
| | public static org.w3c.dom.traversal.NodeIterator | selectNodeIterator(org.w3c.dom.Node contextNode, java.lang.String str)Use an XPath string to select a nodelist.
XPath namespace prefixes are resolved from the contextNode.
return selectNodeIterator(contextNode, str, contextNode);
| | public static org.w3c.dom.traversal.NodeIterator | selectNodeIterator(org.w3c.dom.Node contextNode, java.lang.String str, org.w3c.dom.Node namespaceNode)Use an XPath string to select a nodelist.
XPath namespace prefixes are resolved from the namespaceNode.
// Execute the XPath, and have it return the result
XObject list = eval(contextNode, str, namespaceNode);
// Have the XObject return its result as a NodeSetDTM.
return list.nodeset();
| | public static org.w3c.dom.NodeList | selectNodeList(org.w3c.dom.Node contextNode, java.lang.String str)Use an XPath string to select a nodelist.
XPath namespace prefixes are resolved from the contextNode.
return selectNodeList(contextNode, str, contextNode);
| | public static org.w3c.dom.NodeList | selectNodeList(org.w3c.dom.Node contextNode, java.lang.String str, org.w3c.dom.Node namespaceNode)Use an XPath string to select a nodelist.
XPath namespace prefixes are resolved from the namespaceNode.
// Execute the XPath, and have it return the result
XObject list = eval(contextNode, str, namespaceNode);
// Return a NodeList.
return list.nodelist();
| | public static org.w3c.dom.Node | selectSingleNode(org.w3c.dom.Node contextNode, java.lang.String str)Use an XPath string to select a single node. XPath namespace
prefixes are resolved from the context node, which may not
be what you want (see the next method).
return selectSingleNode(contextNode, str, contextNode);
| | public static org.w3c.dom.Node | selectSingleNode(org.w3c.dom.Node contextNode, java.lang.String str, org.w3c.dom.Node namespaceNode)Use an XPath string to select a single node.
XPath namespace prefixes are resolved from the namespaceNode.
// Have the XObject return its result as a NodeSetDTM.
NodeIterator nl = selectNodeIterator(contextNode, str, namespaceNode);
// Return the first node, or null
return nl.nextNode();
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