Mega Code Archive
Gets the child of the specified element having the specified name If the child with this name doesnt exist then null is returned inste
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import java.util.ArrayList;
import java.util.Iterator;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
/**
* A utility class to cover up the rough bits of xml parsing
*
* @author <a href="mailto:chris@kimptoc.net">Chris Kimpton</a>
* @version $Revision: 2787 $
*/
@SuppressWarnings("unchecked")
public class XmlHelper {
/**
* Returns an iterator over the children of the given element with the given
* tag name.
*
* @param element
* The parent element
* @param tagName
* The name of the desired child
* @return An interator of children or null if element is null.
*/
public static Iterator getChildrenByTagName(Element element, String tagName) {
if (element == null)
return null;
// getElementsByTagName gives the corresponding elements in the whole
// descendance. We want only children
NodeList children = element.getChildNodes();
ArrayList goodChildren = new ArrayList();
for (int i = 0; i < children.getLength(); i++) {
Node currentChild = children.item(i);
if (currentChild.getNodeType() == Node.ELEMENT_NODE
&& ((Element) currentChild).getTagName().equals(tagName)) {
goodChildren.add(currentChild);
}
}
return goodChildren.iterator();
}
/**
* Gets the child of the specified element having the specified unique name.
* If there are more than one children elements with the same name and
* exception is thrown.
*
* @param element
* The parent element
* @param tagName
* The name of the desired child
* @return The named child.
*
* @throws Exception
* Child was not found or was not unique.
*/
public static Element getUniqueChild(Element element, String tagName) throws Exception {
Iterator goodChildren = getChildrenByTagName(element, tagName);
if (goodChildren != null && goodChildren.hasNext()) {
Element child = (Element) goodChildren.next();
if (goodChildren.hasNext()) {
throw new Exception("expected only one " + tagName + " tag");
}
return child;
} else {
throw new Exception("expected one " + tagName + " tag");
}
}
/**
* Gets the child of the specified element having the specified name. If the
* child with this name doesn't exist then null is returned instead.
*
* @param element
* the parent element
* @param tagName
* the name of the desired child
* @return either the named child or null
* @throws Exception
*/
public static Element getOptionalChild(Element element, String tagName) throws Exception {
return getOptionalChild(element, tagName, null);
}
/**
* Gets the child of the specified element having the specified name. If the
* child with this name doesn't exist then the supplied default element is
* returned instead.
*
* @param element
* the parent element
* @param tagName
* the name of the desired child
* @param defaultElement
* the element to return if the child doesn't exist
* @return either the named child or the supplied default
* @throws Exception
*/
public static Element getOptionalChild(Element element, String tagName, Element defaultElement)
throws Exception {
Iterator goodChildren = getChildrenByTagName(element, tagName);
if (goodChildren != null && goodChildren.hasNext()) {
Element child = (Element) goodChildren.next();
if (goodChildren.hasNext()) {
throw new Exception("expected only one " + tagName + " tag");
}
return child;
} else {
return defaultElement;
}
}
/**
* Get the content of the given element.
*
* @param element
* The element to get the content for.
* @return The content of the element or null.
* @throws Exception
*/
public static String getElementContent(final Element element) throws Exception {
return getElementContent(element, null);
}
/**
* Get the content of the given element.
*
* @param element
* The element to get the content for.
* @param defaultStr
* The default to return when there is no content.
* @return The content of the element or the default.
* @throws Exception
*/
public static String getElementContent(Element element, String defaultStr) throws Exception {
if (element == null)
return defaultStr;
NodeList children = element.getChildNodes();
String result = "";
for (int i = 0; i < children.getLength(); i++) {
if (children.item(i).getNodeType() == Node.TEXT_NODE
|| children.item(i).getNodeType() == Node.CDATA_SECTION_NODE) {
result += children.item(i).getNodeValue();
} else if (children.item(i).getNodeType() == Node.COMMENT_NODE) {
// Ignore comment nodes
}
}
return result.trim();
}
/**
* Macro to get the content of a unique child element.
*
* @param element
* The parent element.
* @param tagName
* The name of the desired child.
* @return The element content or null.
* @throws Exception
*/
public static String getUniqueChildContent(Element element, String tagName) throws Exception {
return getElementContent(getUniqueChild(element, tagName));
}
/**
* Macro to get the content of an optional child element.
*
* @param element
* The parent element.
* @param tagName
* The name of the desired child.
* @return The element content or null.
* @throws Exception
*/
public static String getOptionalChildContent(Element element, String tagName) throws Exception {
return getElementContent(getOptionalChild(element, tagName));
}
public static boolean getOptionalChildBooleanContent(Element element, String name)
throws Exception {
Element child = getOptionalChild(element, name);
if (child != null) {
String value = getElementContent(child).toLowerCase();
return value.equals("true") || value.equals("yes");
}
return false;
}
}
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