java下載檔案功能，匯出的時候會下載到瀏覽器預設下載資料夾裡，360瀏覽器會彈出一個儲存檔案的彈出框
//下載匯出報表
//JS
function downloadExport(filename){
window.location.href=”/order-center/ui/spm/downloadExport.do?filename=”+filename;
}

/**
 * 查詢匯出報表： http://localhost:8080/order-center/ui/spm/downloadExport.do
 * key module
 */
@RequestMapping(value = "downloadExport.do", method = RequestMethod.GET)
public void downloadExport(
        @RequestParam(value = "filename", required = false) String filename,
        HttpServletResponse response) {
    File pf = new File(SpmRest.class.getResource("/").getFile());
    FileInputStream fis=null;
    OutputStream ostream=null;
    try {
//          if (!getUser().getShopid().equals(EGlobal.TOP_SHOP_ID)) {
////                shopId = getUser().getShopid();
//              shopId = spmService.getUserShopList(getUser(),shopId);
//          }
        String dirPath = pf.getParentFile().getParentFile().getAbsolutePath()+ File.separator + "exportfile";
        File dirFile = new File(dirPath);
        if (!dirFile.exists())
            dirFile.mkdir();


        File file = new File(dirFile.getAbsolutePath() + File.separator
                + filename);
        if (!file.exists()) {//查詢伺服器有沒有檔案，沒有則衝FTP下載
            boolean downloadExport = spmService.downloadExport(dirPath, filename);
            if(!downloadExport){
                return ;
            }
        }
        fis = new FileInputStream(file);
        ostream = response.getOutputStream();
        response.setContentType("application/ms-excel");
        response.setHeader("Content-disposition", "attachment; filename="+ filename);
        byte[] b = new byte[1024];
        int len = fis.read(b);
        while (len > 0) {
            ostream.write(b, 0, len);
            len = fis.read(b);
        }   
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            fis.close();
            ostream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }   
    }
}
/** 
 *  從ftp下載報表
 * @throws SftpException 
 */
public boolean downloadExport(String dirPath, String filename) {
    boolean flag = false;
    ChannelSftp sftp = null;
    SFTPUtilTools sftptool = null;//連線FTP，自定義類，網上很多示例
    try{
        sftptool =  new SFTPUtilTools();
        sftp = sftptool.connectChannel(FGlobal.EXPORT_HOSTNAME, FGlobal.EXPORT_USERNAME, FGlobal.EXPORT_PASSWORD);
        if (sftp == null) {
            logger.warn("無效連結或連結失敗");
            return flag;
        }
        logger.info("**************開始下載匯出報表EXPORT**************");
        sftp.cd(FGlobal.EXPORT_REC);//進入ftp下載資料夾
        File file = new File(dirPath+File.separator+filename);//匯出到伺服器檔案
        sftp.get(filename,new FileOutputStream(file));//下載檔案
        System.out.println("檔案更新成功：" + file.getName());
        flag = true;
        logger.info("**************下載檔案成功**************");
    }catch(Exception e){
        logger.error(e);
    }finally{
        sftptool.closeChannel(sftp);
    }
    return flag;
}