如何指定要由Java Sax解析器解析的XML文件的一部分？

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class XMLParserExample {
    public static void main(String[] args) {
        try {
            SAXParserFactory factory = SAXParserFactory.newInstance();
            SAXParser saxParser = factory.newSAXParser();
            
            MyHandler handler = new MyHandler();
            saxParser.parse("path/to/xml/file.xml", handler);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

class MyHandler extends DefaultHandler {
    boolean isParsingPart = false;
    String parsedData = "";
    
    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        if (qName.equalsIgnoreCase("part")) {
            isParsingPart = true;
        }
    }
    
    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        if (qName.equalsIgnoreCase("part")) {
            isParsingPart = false;
            // 在这里可以将解析的数据存储到数据结构中或执行其他操作
            System.out.println("Parsed data: " + parsedData);
        }
    }
    
    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        if (isParsingPart) {
            parsedData = new String(ch, start, length);
        }
    }
}