com.sun.org.apache.xpath.internal: public class: XPathAPI

com.sun.org.apache.xpath.internal
public class: XPathAPI [javadoc | source]

java.lang.Object
   com.sun.org.apache.xpath.internal.XPathAPI

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.

Also see:

XPath Specification

Method from com.sun.org.apache.xpath.internal.XPathAPI Summary:
eval, eval, eval, selectNodeIterator, selectNodeIterator, selectNodeList, selectNodeList, selectSingleNode, selectSingleNode

Methods from java.lang.Object:
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from com.sun.org.apache.xpath.internal.XPathAPI Detail:
public static XObject eval(Node contextNode, String str) throws TransformerException { return eval(contextNode, str, contextNode); } Evaluate XPath string to an XObject. Using this method, XPath namespace prefixes will be resolved from the namespaceNode.
public static XObject eval(Node contextNode, String str, Node namespaceNode) throws TransformerException { // 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); } 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.
public static XObject eval(Node contextNode, String str, PrefixResolver prefixResolver) throws TransformerException { // 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); } 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.
public static NodeIterator selectNodeIterator(Node contextNode, String str) throws TransformerException { return selectNodeIterator(contextNode, str, contextNode); } Use an XPath string to select a nodelist. XPath namespace prefixes are resolved from the contextNode.
public static NodeIterator selectNodeIterator(Node contextNode, String str, Node namespaceNode) throws TransformerException { // 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(); } Use an XPath string to select a nodelist. XPath namespace prefixes are resolved from the namespaceNode.
public static NodeList selectNodeList(Node contextNode, String str) throws TransformerException { return selectNodeList(contextNode, str, contextNode); } Use an XPath string to select a nodelist. XPath namespace prefixes are resolved from the contextNode.
public static NodeList selectNodeList(Node contextNode, String str, Node namespaceNode) throws TransformerException { // Execute the XPath, and have it return the result XObject list = eval(contextNode, str, namespaceNode); // Return a NodeList. return list.nodelist(); } Use an XPath string to select a nodelist. XPath namespace prefixes are resolved from the namespaceNode.
public static Node selectSingleNode(Node contextNode, String str) throws TransformerException { return selectSingleNode(contextNode, str, contextNode); } 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).
public static Node selectSingleNode(Node contextNode, String str, Node namespaceNode) throws TransformerException { // Have the XObject return its result as a NodeSetDTM. NodeIterator nl = selectNodeIterator(contextNode, str, namespaceNode); // Return the first node, or null return nl.nextNode(); } Use an XPath string to select a single node. XPath namespace prefixes are resolved from the namespaceNode.

Method from com.sun.org.apache.xpath.internal.XPathAPI Detail:

 public static XObject eval(Node contextNode,
    String str) throws TransformerException {
    return eval(contextNode, str, contextNode);
}

Evaluate XPath string to an XObject. Using this method, XPath namespace prefixes will be resolved from the namespaceNode.

 public static XObject eval(Node contextNode,
    String str,
    Node namespaceNode) throws TransformerException {
    // 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);
}

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.

 public static XObject eval(Node contextNode,
    String str,
    PrefixResolver prefixResolver) throws TransformerException {
    // 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 NodeIterator selectNodeIterator(Node contextNode,
    String str) throws TransformerException {
    return selectNodeIterator(contextNode, str, contextNode);
}

Use an XPath string to select a nodelist. XPath namespace prefixes are resolved from the contextNode.

 public static NodeIterator selectNodeIterator(Node contextNode,
    String str,
    Node namespaceNode) throws TransformerException {
    // 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();
}

Use an XPath string to select a nodelist. XPath namespace prefixes are resolved from the namespaceNode.

 public static NodeList selectNodeList(Node contextNode,
    String str) throws TransformerException {
    return selectNodeList(contextNode, str, contextNode);
}

Use an XPath string to select a nodelist. XPath namespace prefixes are resolved from the contextNode.

 public static NodeList selectNodeList(Node contextNode,
    String str,
    Node namespaceNode) throws TransformerException {
    // Execute the XPath, and have it return the result
    XObject list = eval(contextNode, str, namespaceNode);
    // Return a NodeList.
    return list.nodelist();
}

Use an XPath string to select a nodelist. XPath namespace prefixes are resolved from the namespaceNode.

 public static Node selectSingleNode(Node contextNode,
    String str) throws TransformerException {
    return selectSingleNode(contextNode, str, contextNode);
}

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).

 public static Node selectSingleNode(Node contextNode,
    String str,
    Node namespaceNode) throws TransformerException {
    // Have the XObject return its result as a NodeSetDTM.
    NodeIterator nl = selectNodeIterator(contextNode, str, namespaceNode);
    // Return the first node, or null
    return nl.nextNode();
}

Use an XPath string to select a single node. XPath namespace prefixes are resolved from the namespaceNode.