import jdk.internal.org.xml.sax.Attributes; //导入依赖的package包/类
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes)
    throws SAXException
{
    if (rootElem < 2) {
        rootElem++;
    }

    if (rootElm == null) {
        fatalError(new SAXParseException("An XML properties document must contain"
                + " the DOCTYPE declaration as defined by java.util.Properties.", null));
    }

    if (rootElem == 1 && !rootElm.equals(qName)) {
        fatalError(new SAXParseException("Document root element \"" + qName
                + "\", must match DOCTYPE root \"" + rootElm + "\"", null));
    }
    if (!ALLOWED_ELEMENTS.contains(qName)) {
        fatalError(new SAXParseException("Element type \"" + qName + "\" must be declared.", null));
    }
    if (qName.equals(ELEMENT_ENTRY)) {
        validEntry = true;
        key = attributes.getValue(ATTR_KEY);
        if (key == null) {
            fatalError(new SAXParseException("Attribute \"key\" is required and must be specified for element type \"entry\"", null));
        }
    } else if (qName.equals(ALLOWED_COMMENT)) {
        if (sawComment) {
            fatalError(new SAXParseException("Only one comment element may be allowed. "
                    + "The content of element type \"properties\" must match \"(comment?,entry*)\"", null));
        }
        sawComment = true;
    }
}
 

import jdk.internal.org.xml.sax.Attributes; //导入依赖的package包/类
/**
 * Receive notification of the start of an element.
 *
 * <p>By default, do nothing.  Application writers may override this
 * method in a subclass to take specific actions at the start of
 * each element (such as allocating a new tree node or writing
 * output to a file).</p>
 *
 * @param uri The Namespace URI, or the empty string if the
 *        element has no Namespace URI or if Namespace
 *        processing is not being performed.
 * @param localName The local name (without prefix), or the
 *        empty string if Namespace processing is not being
 *        performed.
 * @param qName The qualified name (with prefix), or the
 *        empty string if qualified names are not available.
 * @param attributes The attributes attached to the element.  If
 *        there are no attributes, it shall be an empty
 *        Attributes object.
 * @exception org.xml.sax.SAXException Any SAX exception, possibly
 *            wrapping another exception.
 * @see org.xml.sax.ContentHandler#startElement
 */
public void startElement (String uri, String localName,
                          String qName, Attributes attributes)
    throws SAXException
{
    // no op
}