URL reportURL = getClass().getResource("reports/Report01.jasper");
        String reportPath = reportURL.getFile();
         try  {
            reportPath = java.net.URLDecoder.decode(reportPath, "cp1251");
            jasperPrint = JasperFillManager.fillReport(reportPath, parameters,  new  JREmptyDataSource());
        }
         catch  (UnsupportedEncodingException e) {
             ....
        }
         catch  (JRException e) {
             System.out.println(e);
        }
    }

net.sf.jasperreports.engine.JRException: file:\C:\Temp\MyJar\MyJar.jar!
\abc\sd\MyClasses\reports\Report01.jasper