DOM Utils
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import org.w3c.dom.*;
/**
* @author Matthew J. Duftler
* @author Sanjiva Weerawarana
*/
public class DOMUtils {
/**
* The namespaceURI represented by the prefix <code>xmlns</code>.
*/
private static String NS_URI_XMLNS = "http://www.w3.org/2000/xmlns/";
/**
* Returns the value of an attribute of an element. Returns null
* if the attribute is not found (whereas Element.getAttribute
* returns "" if an attrib is not found).
*
* @param el Element whose attrib is looked for
* @param attrName name of attribute to look for
* @return the attribute value
*/
static public String getAttribute (Element el, String attrName) {
String sRet = null;
Attr attr = el.getAttributeNode(attrName);
if (attr != null) {
sRet = attr.getValue();
}
return sRet;
}
/**
* Returns the value of an attribute of an element. Returns null
* if the attribute is not found (whereas Element.getAttributeNS
* returns "" if an attrib is not found).
*
* @param el Element whose attrib is looked for
* @param namespaceURI namespace URI of attribute to look for
* @param localPart local part of attribute to look for
* @return the attribute value
*/
static public String getAttributeNS (Element el,
String namespaceURI,
String localPart) {
String sRet = null;
Attr attr = el.getAttributeNodeNS (namespaceURI, localPart);
if (attr != null) {
sRet = attr.getValue ();
}
return sRet;
}
/**
* Concat all the text and cdata node children of this elem and return
* the resulting text.
*
* @param parentEl the element whose cdata/text node values are to
* be combined.
* @return the concatanated string.
*/
static public String getChildCharacterData (Element parentEl) {
if (parentEl == null) {
return null;
}
Node tempNode = parentEl.getFirstChild();
StringBuffer strBuf = new StringBuffer();
CharacterData charData;
while (tempNode != null) {
switch (tempNode.getNodeType()) {
case Node.TEXT_NODE :
case Node.CDATA_SECTION_NODE : charData = (CharacterData)tempNode;
strBuf.append(charData.getData());
break;
}
tempNode = tempNode.getNextSibling();
}
return strBuf.toString();
}
/**
* Return the first child element of the given element. Null if no
* children are found.
*
* @param elem Element whose child is to be returned
* @return the first child element.
*/
public static Element getFirstChildElement (Element elem) {
for (Node n = elem.getFirstChild (); n != null; n = n.getNextSibling ()) {
if (n.getNodeType () == Node.ELEMENT_NODE) {
return (Element) n;
}
}
return null;
}
/**
* Return the next sibling element of the given element. Null if no
* more sibling elements are found.
*
* @param elem Element whose sibling element is to be returned
* @return the next sibling element.
*/
public static Element getNextSiblingElement (Element elem) {
for (Node n = elem.getNextSibling (); n != null; n = n.getNextSibling ()) {
if (n.getNodeType () == Node.ELEMENT_NODE) {
return (Element) n;
}
}
return null;
}
/**
* Return the first child element of the given element which has the
* given attribute with the given value.
*
* @param elem the element whose children are to be searched
* @param attrName the attrib that must be present
* @param attrValue the desired value of the attribute
*
* @return the first matching child element.
*/
public static Element findChildElementWithAttribute (Element elem,
String attrName,
String attrValue) {
for (Node n = elem.getFirstChild (); n != null; n = n.getNextSibling ()) {
if (n.getNodeType () == Node.ELEMENT_NODE) {
if (attrValue.equals (DOMUtils.getAttribute ((Element) n, attrName))) {
return (Element) n;
}
}
}
return null;
}
/**
* Count number of children of a certain type of the given element.
*
* @param elem the element whose kids are to be counted
*
* @return the number of matching kids.
*/
public static int countKids (Element elem, short nodeType) {
int nkids = 0;
for (Node n = elem.getFirstChild (); n != null; n = n.getNextSibling ()) {
if (n.getNodeType () == nodeType) {
nkids++;
}
}
return nkids;
}
/**
* Given a prefix and a node, return the namespace URI that the prefix
* has been associated with. This method is useful in resolving the
* namespace URI of attribute values which are being interpreted as
* QNames. If prefix is null, this method will return the default
* namespace.
*
* @param context the starting node (looks up recursively from here)
* @param prefix the prefix to find an xmlns:prefix=uri for
*
* @return the namespace URI or null if not found
*/
public static String getNamespaceURIFromPrefix (Node context,
String prefix) {
short nodeType = context.getNodeType ();
Node tempNode = null;
switch (nodeType)
{
case Node.ATTRIBUTE_NODE :
{
tempNode = ((Attr) context).getOwnerElement ();
break;
}
case Node.ELEMENT_NODE :
{
tempNode = context;
break;
}
default :
{
tempNode = context.getParentNode ();
break;
}
}
while (tempNode != null && tempNode.getNodeType () == Node.ELEMENT_NODE)
{
Element tempEl = (Element) tempNode;
String namespaceURI = (prefix == null)
? getAttribute (tempEl, "xmlns")
: getAttributeNS (tempEl, NS_URI_XMLNS, prefix);
if (namespaceURI != null)
{
return namespaceURI;
}
else
{
tempNode = tempEl.getParentNode ();
}
}
return null;
}
public static Element getElementByID(Element el, String id)
{
if (el == null)
return null;
String thisId = el.getAttribute("id");
if (id.equals(thisId))
return el;
NodeList list = el.getChildNodes();
for (int i = 0; i < list.getLength(); i++) {
Node node = list.item(i);
if (node instanceof Element) {
Element ret = getElementByID((Element)node, id);
if (ret != null)
return ret;
}
}
return null;
}
}
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