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;
?>