微信小程序用户授权，以及判断登录是否过期的方法

<button bindtap="login">登录</button>
<button bindtap="checksession">登录是否过期</button>
<button open-type="getUserInfo" bindgetuserinfo="info">点击授权</button>
<text>{{city}}</text>
<text>{{country}}</text>
<text>{{nickName}}</text>
<text>{{province}}</text>

//index.js
//获取应用实例
const app = getApp()
 
Page({
 data: {
  city:'',
  country:'',
  nickName:'',
  province:''
 },
 //发起http请求
 login:function(){
  wx.login({
   success:function(res){
    console.log(res.code)
    //发送请求
    wx.request({
     url: '自己的域名', //仅为示例，并非真实的接口地址
     data: {
      code:res.code
     },
     header: {
      'content-type': 'application/json' // 默认值
     },
     success(res) {
      console.log(res)
     }
    })
   }
  })
 },
 //验证登录是否过期
 checksession:function(){
  wx.checkSession({
   success:function(res){
    console.log(res,'登录未过期')
    wx.showToast({
     title: '登录未过期啊',
    })
   },
   fail:function(res){
    console.log(res,'登录过期了')
    wx.showModal({
     title: '提示',
     content: '你的登录信息过期了，请重新登录',
    })
    //再次调用wx.login()
    wx.login({
     success: function (res) {
      console.log(res.code)
      //发送请求
      wx.request({
       url: '自己的域名', //仅为示例，并非真实的接口地址
       data: {
        code: res.code
       },
       header: {
        'content-type': 'application/json' // 默认值
       },
       success(res) {
        console.log(res)
       }
      })
     }
    })
   }
  })
 },
 //获取用户的信息
 info:function(){
  var that=this
  wx.getUserInfo({
   success:function(res){
    console.log(res.userInfo)
    var city = res.userInfo.city
    var country = res.userInfo.country
    var nickName = res.userInfo.nickName
    var province = res.userInfo.province
    that.setData({
     city:city,
     country:country,
     nickName:nickName,
     province:province
    })
   }
  })
 }
})

<?php
//声明code，用来接收前台传过来的code
$code=$_GET['code'];
 
//获取到appid
$appid="xxxxxxxxxxx"; //自己的appid
$secret="xxxxxxxxxxxx";  //自己的secret
$api="https://api.weixin.qq.com/sns/jscode2session?appid={$appid}&secret={$secret}&js_code={$code}&grant_type=authorization_code";  //可去小程序开发文档中查看这个链接
 
//发送的代码
function httpGet($url){
	$curl=curl_init();
	curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($curl, CURLOPT_TIMEOUT, 500);
	curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, true);
	curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, true);
	curl_setopt($curl, CURLOPT_URL, $url);
	$res= curl_exec($curl);
	curl_close($curl);
	return $res;
}
 
$str=httpGet($api);
 
echo $str;
?>