// 解决不同浏览器下载文件名称乱码
var userAgent = (req.headers['user-agent']||'').toLowerCase();
res.set('Content-Type', 'application/octet-stream;charset=utf-8');

if(userAgent.indexOf('msie') >= 0 || userAgent.indexOf('chrome') >= 0) {
   res.setHeader('Content-Disposition', 'attachment; filename=' +
   encodeURIComponent(filename));
} else if(userAgent.indexOf('firefox') >= 0) {
   res.setHeader('Content-Disposition', 'attachment; filename*="utf8\'\'' +
   encodeURIComponent(filename)+'"');
} else {
   res.setHeader('Content-Disposition', 'attachment; filename=' +
   new Buffer(filename).toString('binary'));
}

// 解决excel打开内容乱码
var dataBuffer = Buffer.concat([new Buffer('\xEF\xBB\xBF', 'binary'), new Buffer(data)]);
res.send(dataBuffer);