data = Buffer.concat([new Buffer('\xEF\xBB\xBF', 'binary'), new Buffer(_data)]); //excel需要BOM，每次写入数据前先加入一个utf8的BOM。utf-8对应的BOM是 EF BB BF

        let fileUrl = URL + queryString;// download filelet _this = this;http.get(fileUrl, function (response) { //设置请求头_this.res.setHeader('Content-disposition', 'attachment; filename=orderData.csv');response.setEncoding('binary');  //二进制binary

            var data = '';response.on('data', function (_data) {    //node的http模块对报文内容通过data事件触发，我们只需以流的方式处理即可

                 data = Buffer.concat([new Buffer('binary'), new Buffer(_data)]);}).on('end', function () {          data = iconv.decode( data.toString(), 'GBK');var buffer = new Buffer(data);var str=iconv.encode(buffer,'GBK'); _this.res.send(str)})  }) 

<form action="/upload" method="post"><label> <input type="text" /> </label><input type="submit" /></form>var hasBody = function(){return 'transfer-encoding' in req.headers || 'content-length' in req,headers;}function (req, res){if( hasBody(req) ){var buffers = [ ];req.on( 'data', function (chunk){buffers.push( chunk );} )req.on( 'end', function ( ){req,rawBody = Buffer.concat(buffers).toString( );handle(req,res);} )}else{habdle(req, res)}}var handle = function(req, res) {if( req.headers['content-type'] === 'application/x-www-form-urlencode' ){ //报文体req.body = querystring.parse(req.rawBody);}todo(req, res);}

function (req, res){if(hasBody(req)){if(mime(req) === 'multipart/form-data') {var form = new formidable.IncomingForm();form.parse(req, function(err, fields, files){req.body = fields;req.files = files;handle(req, res);})}} else{handle(req, res);}
}