关于Dom4j xslt 转换的问题 求助

public String styleDocument(Document document, String stylesheet) throws Exception {
    // load the transformer using JAXP
    TransformerFactory factory = TransformerFactory.newInstance();
    Transformer transformer = factory.newTransformer(new StreamSource( stylesheet ));
    // now lets style the given document
    DocumentSource source = new DocumentSource( document );
    DocumentResult result = new DocumentResult();
    transformer.transform( source, result );
    // return the transformed document
    Document transformedDoc = result.getDocument();
    return transformedDoc.asXML();
}

使用上面的方法出现错误
错误：“no protocol: <?xml version="1.0" encoding="UTF-8"?><xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">  <xsl:template match="/">    <h1>      <xsl:value-of select="//title"/>    </h1>    <h2>      <xsl:value-of select="//author"/>    </h2>  </xsl:template></xsl:stylesheet>”
致命错误：“无法编译样式表”
请高手指教!!!