如何在<fo:block>和/或<fo:table>维度被渲染到xslfo之前获取它们？

<xsl:template match="/">
  <xsl:apply-templates select="//fo:block"/>
</xsl:template>

import org.apache.fop.apps.FopFactory;
import org.apache.fop.apps.Fop;
import org.apache.fop.apps.MimeConstants;
import org.w3c.dom.Document;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
import java.io.File;
import java.io.FileOutputStream;

public class XSLFOExample {
  public static void main(String[] args) throws Exception {
    // Load XML data
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    Document xml = builder.parse(new File("input.xml"));

    // Load XSLT stylesheet
    TransformerFactory transformerFactory = TransformerFactory.newInstance();
    StreamSource xslt = new StreamSource(new File("stylesheet.xsl"));
    Transformer transformer = transformerFactory.newTransformer(xslt);

    // Apply XSLT transformation
    DOMSource source = new DOMSource(xml);
    StreamResult result = new StreamResult(new FileOutputStream("output.fo"));
    transformer.transform(source, result);

    // Get <fo:block> and <fo:table> elements from the generated XSL-FO
    FopFactory fopFactory = FopFactory.newInstance(new File(".").toURI());
    Fop fop = fopFactory.newFop(MimeConstants.MIME_FOP_IF, new FileOutputStream("output.pdf"));
    // ...
  }
}