// used PdfReport to generate PDF report
PdfReport pdfReport = new PdfReport();
outputStream = pdfReport.generatePdfReport(jasperPrint);
} else if (reportType.equals("excel")) {
//use ExcelReport to generate Excel report
ExcelReport excelReport = new ExcelReport();
outputStream = excelReport.generateExcelReport(jasperPrint);
} else if (reportType.equals("html")) {
// used HtmlReport to generate HTML report
HtmlReport htmlReport = new HtmlReport();
outputStream = htmlReport.generateHtmlReport(jasperPrint);
} else {