nodejs如何提供本地文件的http访问路径？

Question

一个上传图片返回url的nodejs程序，返回{  "name": "name",  "url": "/uploader/upload"}怎么才能将本地路径转化成http路径呢，比如 example.com/upload/a.jpgrouter.post('/', function (req, res) {    if (req.busboy) {        var name = ''        req.busboy.on('file', function (fieldname, file, fileName, encoding, mimeType) {            name = fileName            var stream = fs.createWriteStream(path.join(__dirname, '../', uploadPath, fileName))            file.pipe(stream)            console.log('uploading %s -> %s', fileName, stream.path)        }).on('finish', function () {            res.send({                name: 'name',                url: path.join(uploadPath, name)            })        })        req.pipe(req.busboy)    } else {        console.log('uploadFile - busboy undefined.')        res.status(502)    }})