npm install formidable -D

const formidable = require('formidable');

 router.post('/uploadFile', (req, res, next) => {

   let form = new formidable.IncomingForm();

   form.encoding = 'utf-8';

   //上传到服务器指定文件夹

   form.uploadDir =`public/${constant.UPLOAD_FOLDER}`;

   form.keepExtensions = true;     //保留后缀

   form.maxFieldsSize = constant.IMAGE_SIZE;

   let data = new MsgBean('上传失败',1);

   form.parse(req, (err, fields, files) => {

     if (err) {

       data.setContent(err);

       res.send(data);

       return;

     }

     let file = files.file;

     let fileType = new RegExp(file.type, 'g');

     let isLegal = fileType.test(constant.IMAGE_TYPE);

     if(!isLegal) {//判断上传图片格式是否合法

         data.msg('非法的图片格式');

         res.send(data);

         return;

     }

     let fileSize = file.size;

     if(fileSize > constant.IMAGE_SIZE) {//上传图片超出最大限度

         data.msg('图片大小超出最大限制');

         res.send(data);

         return;

     }

     let index = file.name.lastIndexOf('.');

     let oldPath = files.file.path;

     let uploadDate = new Date().getTime();

     let fileName = `${file.name.slice(0, index)}_${uploadDate}_origin.${file.name.slice(index+1)}`;

     let newPath = `public/${constant.UPLOAD_FOLDER}/${fileName}`;

     fs.rename(oldPath, newPath, err => {//图片更名

         if(err) {

             data.setContent('图片解析失败');

             res.send(data);

             return;

         }

         let baseUrl = req.headers.host;

         let imgUrl = `http://${baseUrl}/${constant.UPLOAD_FOLDER}/${fileName}`;

         let result =  {

             imgUrl

         };

         data.setCode(0);

         data.setContent(result);

         data.setMsg('上传成功');

         res.send(data);

     });

   })

 });