Minor enhancements to XmlPullWrapper and XmlSerializerWrapper

Hi Alek,

I have made a minor enhancement to these wrappers to recognize the
xsi:nil attribute. Do you think this should go in to the utility
wrappers you are writing?
Thanks.
Naresh

public class XmlPullWrapper {
    
    static final String
XSI_NS="http://www.w3.org/2001/XMLSchema-instance";
    ...

    /**
     * Read the text of a required element and return it or throw
exception if
     * required element is not found. Useful for getting the text of
simple
     * elements such as <username>johndoe</username>. Assumes that
parser is
     * just before the start tag and leaves the parser at the end tag.
If the
     * text is nil (e.g. <username xsi:nil="true"/>), then a null will
be returned.
     */

    public String getRequiredElementText(String namespace, String name)
        throws IOException, XmlPullParserException {
            if (name == null) {
                throw new XmlPullParserException("name for element can
not be null");
            }
            
            String text = null;
            nextStartTag(namespace, name);
            if (isNil()) {
                nextEndTag(namespace, name);
            }
            else {
                text = parser.nextText();
            }
            parser.require(XmlPullParser.END_TAG, namespace, name);
            return text;
    }
    
    /**
     * Is the current tag nil? Checks for xsi:nil="true".
     */
    public boolean isNil()
        throws IOException, XmlPullParserException {
            
        boolean result = false;
        String value = parser.getAttributeValue(XSI_NS, "nil");
        if ("true".equals(value)) {
            result = true;
        }
        
        return result;
    }
}

public class XmlSerializerWrapper {

    static final String
XSI_NS="http://www.w3.org/2001/XMLSchema-instance";
    
    /**
     * The serializer used to write XML output. It is the responsibility
of the subclass
     * to initialize this member.
     */
    protected XmlSerializer serializer;

    /**
     * Writes a simple element such as <username>johndoe</username>. The
namespace
     * and elementText are allowed to be null. If elementText is null,
an xsi:nil="true"
     * will be added as an attribute.
     */
    public void writeSimpleElement(String namespace, String elementName,
String elementText)
    throws IOException, XmlPullParserException {
        
        if (elementName == null) {
            throw new XmlPullParserException("name for element can not
be null");
        }
        
        serializer.startTag(namespace, elementName);
        if (elementText == null) {
            serializer.attribute(XSI_NS, "nil", "true");
        }
        else {
            serializer.text(elementText);
        }
        serializer.endTag(namespace, elementName);
    }
}