nodejs返回下载文档，文档名称出现汉字出现乱码解决

var userAgent = (req.headers['user-agent']||'').toLowerCase();
if(userAgent.indexOf('msie') >= 0 || userAgent.indexOf('chrome') >= 0) {
res.setHeader('Content-Disposition', 'attachment; filename=' + encodeURIComponent(filename));
res.download(path,encodeURIComponent(filename),function(err){
if(err){
console.log(err);
}
});
} else if(userAgent.indexOf('firefox') >= 0) {
res.setHeader('Content-Disposition', 'attachment; filename*="utf8\'\'' + new Buffer(filename).toString('binary')+'"');
res.download(path,new Buffer(filename).toString('binary'),function(err){
if(err){
console.log(err);
}
});
} else if(userAgent.indexOf('gecko') >= 0) { //ie11
res.setHeader('Content-Disposition', 'attachment; filename*="utf8\'\'' + encodeURIComponent(filename)+'"');
res.download(path,encodeURIComponent(filename),function(err){
if(err){
console.log(err);
}
});
} else {
/* safari等其他非主流浏览器只能自求多福了 */
res.setHeader('Content-Disposition', 'attachment; filename=' + new Buffer(filename).toString('binary'));
res.download(path,new Buffer(filename).toString('binary'),function(err){
if(err){
console.log(err);
}
});
}