微信公众平台网页获取用户OpenID方法

具体方法

1、配置网页授权回调域名，如 www.jiaochengji.com

2、模拟公众号的第三方网页，http://www.jiaochengji.com/getcodeurl.php

    <?php  
      
    if(isset($_SESSION['user'])){  
        print_r($_SESSION['user']);
    exit;
    }
    $APPID='公众号在微信的appid';
    $REDIRECT_URI='http://www.jiaochengji.com/callback.php';
    $scope='snsapi_base';
    //$scope='snsapi_userinfo';//需要授权
    $url='https://open.weixin.qq.com/connect/oauth2/authorize?appid='.$APPID.'&redirect_uri='.urlencode($REDIRECT_URI).'&response_type=code&scope='.$scope.'&state='.$state.'#wechat_redirect';
    
    header("Location:".$url);
    ?>

3、第三方网页的回跳url中，首先从请求中取得code，然后根据code进一步换取openid和access_token，然后就可以根据openid和access_token调用微信的相关接口查询用户信息了。

    <?php
    //http://www.jiaochengji.com/callback.php
      
    $appid = "公众号在微信的appid";  
    $secret = "公众号在微信的app secret";  
    $code = $_GET["code"];  
    $get_token_url = 'https://api.weixin.qq.com/sns/oauth2/access_token?appid='.$appid.'&secret='.$secret.'&code='.$code.'&grant_type=authorization_code';

    $ch = curl_init();  
    curl_setopt($ch,CURLOPT_URL,$get_token_url);  
    curl_setopt($ch,CURLOPT_HEADER,0);  
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1 );  
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);  
    $res = curl_exec($ch);  
    curl_close($ch);  
    $json_obj = json_decode($res,true);  
      
    //根据openid和access_token查询用户信息  
    $access_token = $json_obj['access_token'];  
    $openid = $json_obj['openid'];  
    $get_user_info_url = 'https://api.weixin.qq.com/sns/userinfo?access_token='.$access_token.'&openid='.$openid.'&lang=zh_CN';  
      
    $ch = curl_init();  
    curl_setopt($ch,CURLOPT_URL,$get_user_info_url);  
    curl_setopt($ch,CURLOPT_HEADER,0);  
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1 );  
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);  
    $res = curl_exec($ch);  
    curl_close($ch);  
      
    //解析json  
    $user_obj = json_decode($res,true);  
    $_SESSION['user'] = $user_obj;  
    print_r($user_obj);  
      
    ?>  

参考资料

网页授权获取用户基本信息

http://mp.weixin.qq.com/wiki/17/c0f37d5704f0b64713d5d2c37b468d75.html