//添加图片

   addImg: function() {

     var that = this;

     console.log(9 - that.data.checkImgLength)

     if (9 - that.data.checkImgLength >= 1){

       wx.chooseImage({

         count: 9 - that.data.checkImgLength, // 默认9

         sizeType: ['original', 'compressed'], // 可以指定是原图还是压缩图，默认二者都有

         sourceType: ['album', 'camera'], // 可以指定来源是相册还是相机，默认二者都有

         success: function (res) {

           var tempFilePaths = res.tempFilePaths//这里拿到的是图片在微信客户端的临时路径！！！

           let length = tempFilePaths.length;

           let tempList = that.data.imgLists.concat(tempFilePaths);//JSON数据

           that.setData({

             imgLists: tempList,

             checkImgLength: that.data.checkImgLength + length//长度相加，这里是为了选择的图片不会超过9

           })

         }

       })

     }

   },

 var express = require("express");

 var formidable = require("formidable");

 var path = require("path")

 var fs = require("fs")

 var image = require("imageinfo")

 const listenNumber = 5000;

 var app = express();

 app.use(express.static('upload'))//这个很重要，必须要这个才能拿到图片链接，而不是进入路由，有兴趣的同学可以删掉试验一下

 app.post("/upload", (req, res) => {

     var form = new formidable.IncomingForm();//既处理表单，又处理文件上传

     //设置文件上传文件夹/路径，__dirname是一个常量，为当前路径

     let uploadDir = path.join(__dirname, "../upload/");

     form.uploadDir = uploadDir;//本地文件夹目录路径

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

         let oldPath = files.cover.path;//这里的路径是图片的本地路径

         console.log(files.cover.name)//图片传过来的名字

         let newPath = path.join(path.dirname(oldPath), files.cover.name);

         //这里我传回一个下载此图片的Url

         var downUrl = "http://localhost:" + listenNumber + "/upload/" + files.cover.name;//这里是想传回图片的链接

         fs.rename(oldPath, newPath, () => {//fs.rename重命名图片名称

             res.json({ downUrl: downUrl })

         })

     })

 })

 app.listen(listenNumber)

npm install express

npm install formidable

npm install path