jspでtxtファイルを生成する

import jxl.Workbook;  
import jxl.write.Label;  
import jxl.write.WritableSheet;  
import jxl.write.WritableWorkbook;  
  
public class TxtDownLoad extends HttpServlet {  
    public void doGet(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
  
        //  txt  
        try {  
            Date d = new Date();  
            SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd_kkmmss ");  
            String random = sdf.format(d);  
            String targetFile = random + ".csv";  
            response.setContentType("application/x-msdownload");  
            response.addHeader("Content-Disposition",  
                    "attachment;   filename=\"" + targetFile + "\"");  
            OutputStream os = response.getOutputStream();  
            String temp = " ！";  
            os.write(temp.getBytes());  
            os.close();  
            response.flushBuffer();  
  
        } catch (Exception e) {  
            System.out.println(" txt ：");  
            e.printStackTrace();  
        }  
  
    }  
}