将参数从java嵌入式fop传递到xsl文件

我已经在java程序中嵌入了fop：

public class run {

 public static void main(String [ ] args){

    FopFactory fopFactory = FopFactory.newInstance();

    OutputStream out = null;
    try {
        out = new BufferedOutputStream(new FileOutputStream(new File("F:/test.pdf")));
    } catch (FileNotFoundException e) {

        e.printStackTrace();
    }

    try {
      Fop fop = fopFactory.newFop(MimeConstants.MIME_PDF, out);

      TransformerFactory factory = TransformerFactory.newInstance();
      Source xslt = new StreamSource(new File("F:/main_structure.xsl"));
      Transformer transformer = factory.newTransformer(xslt);

      Source src = new StreamSource(new File("F:/source.xml"));

      Result res = new SAXResult(fop.getDefaultHandler());

      transformer.transform(src, res);

    } catch (FOPException e) {
        e.printStackTrace();
    } catch (TransformerConfigurationException e) {
        e.printStackTrace();
    } catch (TransformerException e) {
        e.printStackTrace();
    } finally {
      try {
        out.close();
        System.out.println("ende");
    } catch (IOException e) {
        e.printStackTrace();
    }
    }
 }
}

现在，我的xsl（main_structure.xsl）需要一个参数来运行

    <xsl:param name="OFFSET_LEFT" select="1"/>

在控制台中，我将使用“-param name value”属性将该参数传递给fop

那么，如何在嵌入式版本的fop中将参数传递到xsl文件中呢？

例如，读取：

Transformer transformer = factory.newTransformer(xslt);
transformer.setParameter("PARAMETER", "VALUE");