authLogin () {
  wx.login({
   success: loginRes => {
    let code = loginRes.code // 获取用户临时code
    wx.getUserInfo({
     success: function (res) {
      let encryptedData = res.encryptedData // 获取加密数据
      let iv = res.iv // 解密参数
      // 发送解密必要数据到服务端
      wx.request({
       url: 'http://localhost',
       methods: 'POST',
       data: {
        code: code,
        encryptedData: encryptedData,
        iv: iv
       },
       succeess: res => {
        // 服务端首先调用微信接口获取session_key
        // 用户已经授权过的平台会直接返回unionId
        // 没有授权过则用session_key进行解密
        // 解密成功后服务端根据逻辑返回自定义信息
       }
      })
     }
    })
   }
  })
 }

<button open-type='getUserInfo' bindgetuserinfo="authLogin">微信登录</button>

 // 获取code
 onLoad: function (options) {
  this.getCodeTimer()
 },
 getCodeTimer () {
  wx.login({
   success: res => {
    this.data.code = res.code
    setTimeout(() => {
     this.getCodeTimer()
    }, 4 * 60 * 1000)
   }
  })
 },
 // 授权登录
 authLogin(event) {
  if (event.detail.errMsg == 'getUserInfo:ok') {
   wx.showLoading()
   let reqData = {
    code: this.data.code,
    encryptedData: event.detail.encryptedData,
    iv: event.detail.iv
   }
   wx.request({
    url: 'http://localhost:8080',
    methods: 'POST',
    data: reqData,
    success: (res) => {
     console.log(res)
      // 请求完成
    }
   })
  } else {
   console.log('用户拒绝授权')
  }
 }