text: exports.downloads = function(req, res, next){
  	var filename = req.params.filename
  	  , path = './source/' + filename;
  	res.download(path,function(err){
  		if(err){
  			console.log(path);
  			console.log('download err');
  			next();
  		} else {
  			console.log(path);
  			console.log('ok\n');
  		}
  	});	
  }
  exports.err = function(req, res){
  /*	res.set({
  		encoding : 'utf-8'
  	});
  */
  	res.status(404);
  	res.send("<h1>what you find 找不到了</h1>");
  	res.end();
  }
  