include('./Card/Common/class_weixin_adv.php');

$weixin=new class_weixin_adv("appid", "secret");

$url="https://api.weixin.qq.com/sns/oauth2/access_token?appid=appid&secret=secret&code=".$_GET['code']."&grant_type=authorization_code";
$res = $weixin->https_request($url);//调用SDK方法获取到res 从中可以得到openid
$res=(json_decode($res, true));//转换成array 方便调用openid

$row=$weixin->get_user_info($res['openid']);

public function oauth2(){
 include('./Card/Common/class_weixin_adv.php');
  $weixin=new class_weixin_adv("appid", "secret");
  if (isset($_GET['code'])){
    $url="https://api.weixin.qq.com/sns/oauth2/access_token?appid=appid&secret=secret&code=".$_GET['code']."&grant_type=authorization_code";
    $res = $weixin->https_request($url);
    $res=(json_decode($res, true));
    $row=$weixin->get_user_info($res['openid']);
    if ($row['openid']) {
      //这里写上逻辑,存入cookie,数据库等操作
      cookie('weixin',$row['openid'],25920);
    }else{
      $this->error('授权出错,请重新授权!');
    }
  }else{
    echo "NO CODE";
  }
  $this->display();
}

<?php
/**
 * 微信SDK
 * pan041ymail@gmail.com
 */
class class_weixin_adv
{
  var $appid = "";
  var $appsecret = "";
  //构造函数，获取Access Token
  public function __construct($appid = NULL, $appsecret = NULL)
  {
    if($appid){
      $this->appid = $appid;
    }
    if($appsecret){
      $this->appsecret = $appsecret;
    }
    $this->lasttime = 1395049256;
    $this->access_token = "nRZvVpDU7LxcSi7GnG2LrUcmKbAECzRf0NyDBwKlng4nMPf88d34pkzdNcvhqm4clidLGAS18cN1RTSK60p49zIZY4aO13sF-eqsCs0xjlbad-lKVskk8T7gALQ5dIrgXbQQ_TAesSasjJ210vIqTQ";
    if (time() > ($this->lasttime + 7200)){
      $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=".$this->appid."&secret=".$this->appsecret;
      $res = $this->https_request($url);
      $result = json_decode($res, true);
      $this->access_token = $result["access_token"];
      $this->lasttime = time();
    }
  }
//获取用户基本信息
  public function get_user_info($openid)
  {
    $url = "https://api.weixin.qq.com/cgi-bin/user/info?access_token=".$this->access_token."&openid=".$openid."&lang=zh_CN";
    $res = $this->https_request($url);
    return json_decode($res, true);
  }
//https请求
  public function https_request($url, $data = null)
  {
    $curl = curl_init();
    curl_setopt($curl, CURLOPT_URL, $url);
    curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE);
    curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, FALSE);
    if (!empty($data)){
      curl_setopt($curl, CURLOPT_POST, 1);
      curl_setopt($curl, CURLOPT_POSTFIELDS, $data);
    }
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
    $output = curl_exec($curl);
    curl_close($curl);
    return $output;
  }
}