How to write UTF-8 (Persian) characters in pdf export of dynamic reports?

Question

How to write UTF-8 (Persian) characters in pdf export of dynamic reports?

I am trying to export a report in pdf format using dynamic reports, but Persian characters are not displayed in the pdf file. but i don't have this problem in xls files or in jasper viewer. I tried this method, but it does not work. what should I do?

public void toPdf(String path){
    JasperPdfExporterBuilder pdfExporter = new ExporterBuilders()
    .pdfExporter(path);
    pdfExporter.setCharacterEncoding("UTF-8");
    try {

        jasperReportBuilder.toPdf(pdfExporter);
    } catch (Exception e1) {
        logger.error("failed to create PDF", e1);
    }
}