用code 换取信息的代码：

const https = require(‘https’)

const qs = require(‘querystring’)

const host = require(’./wxhost.json’)

const getOpenid = (query, callback) => {

  let code = query.query.code

  const data = {

    appid: host.appid,

    secret: host.secret,

    grant_type: ‘authorization_code’,

    js_code: code

  }

  let content = qs.stringify(data)

  let url = host.url + ‘sns/jscode2session?’ + content

  https.get(url, function (res) {

    var datas = []

    var size = 0

    res.on(‘data’, function (data) {

      datas.push(data)

      size += data.length

    })

    res.on(‘end’, function () {

      var buff = Buffer.concat(datas, size)

      var result = JSON.parse(buff)

      callback(result)

    })

  }).on(‘error’, function (err) {

    Logger.error(err.stack)

    callback.apply(null)

  })

}

module.exports = getOpenid