中间层代码

var fs = require('fs');
var os = require('os');
var path = require('path');
var parse = require('co-busboy');
var request = require('request');

var uploadFile = function*(file, params, filename, url) {
	return new Promise(function(resolve, reject) {
		var r = request.post(url, function (err, httpResponse, body) {
			if (err) reject(err);
			else resolve(body);
		});

		var form = r.form();
		Object.keys(params).forEach(function(key) {
			form.append(key, params[key]);
		});
		form.append('file', fs.createReadStream(file), {filename: filename});
	});
};

exports.uploadFile = function*() {
  	var parts = parse(this), params = {};
  	var part, stream, url, access_token, file_name;

  	while (part = yield parts) {
  		if (part.fieldname != 'file') {
  			params[part[0]] = part[1];
  			continue;
  		};
    	stream = fs.createWriteStream(path.join(os.tmpdir(), Math.random().toString()));
    	part.pipe(stream);
    	params['file_name'] = params['file_name'] || part.filename;
  	}

  	url = params.url;
  	file_name = params.file_name;
  	delete params.url;
  	delete params.file_name;
  	params.client = 'h5';

  	var result = yield uploadFile(stream.path, params, file_name, url);
  	this.sendJson(result);
}

用于测试的模拟客户端代码

var fs = require('fs');
var request = require('request');

var r = request.post('http://local.middleware.com/service/uploadFile', function optionalCallback(err, httpResponse, body) {
	if (err) throw err;
	console.log(body);
});
var form = r.form();
form.append('accessToken', 'dd0a81a013270eac9466f70c84640b5f');
form.append('url', 'http://localhost:3002');
form.append('file', fs.createReadStream(__dirname + '/unicycle.jpg'), {filename: 'unicycle.jpg'});

用户测试的模拟服务端代码

var http = require('http');
var formidable = require('formidable');

http.createServer(function(req, res) {
	var form = new formidable.IncomingForm();
 
    form.parse(req, function(err, fields, files) {
      console.log(arguments);
      res.end(JSON.stringify(files));
    });
}).listen(3002);

尝试从测试客户端直接提交文件到测试服务端是正常的，但是通过中间层的时候，接受客户端上传正常，但是再上传的时候出现MultipartParser.end(): stream ended unexpectedly: state = PART_DATA] 及[Error: Request aborted]错误，一直看不错中间层哪里有问题，求指点。