try {
OutputStream out = response.getOutputStream();
response.reset()；
response.setHeader("content-disposition",
"attachment;filename="+java.net.URLEncoder.encode(reportName,"UTF-8")+".xls");
response.setContentType("APPLICATION/msexcel");
wb.write(out);
out.close();
} catch (FileNotFoundException e) {
throw new DAOException("");
} catch (IOException e) {
throw new DAOException("");
}