问一些中文字体无法使用iTextpdf显示

EN

static public void main(String[] args) throws Exception {
    Document document = new Document();
    FileOutputStream os = new FileOutputStream(new File("PDF_FILE"));
    PdfWriter.getInstance(document, os);
    document.open();
    BaseFont STXiHei = BaseFont.createFont("STXiHei.ttf",  BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
    BaseFont SongTi = BaseFont.createFont("SongTi.ttc,6", BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
    document.add(new Paragraph("华文细黑", new Font(STXiHei)));
    document.add(new Paragraph("宋体", new Font(SongTi)));
    document.close();
}