1.微信端访问，用户同意授权：

https://open.weixin.qq.com/connect/oauth2/authorize?appid=APPID&redirect_uri=REDIRECT_URI&response_type=code&scope=SCOPE&state=STATE#wechat_redirect

2.同意授权后跳转到第三方URL，通过code参数得到网页授权access_token

https://api.weixin.qq.com/sns/oauth2/access_token?appid=APPID&secret=SECRET&code=CODE&grant_type=authorization_code

3.刷新access_token（如果需要）

https://api.weixin.qq.com/sns/oauth2/refresh_token?appid=APPID&grant_type=refresh_token&refresh_token=REFRESH_TOKEN

3.获取微信用户信息(需scope为 snsapi_userinfo)

使用上一步获取的ACCESS_TOKEN和OPENID

https://api.weixin.qq.com/sns/userinfo?access_token=ACCESS_TOKEN&openid=OPENID&lang=zh_CN

下面我将这个过程写为了一个PHP函数，供大家使用：

/**
 * $appid str 公众号ID
 * $secret str 公众号秘钥
 * $code str 用户授权登录后传过来的参数
 */
function getWechatOpenId($appid,$secret,$code){
    //1.微信端访问，用户同意授权
    //2.同意授权后跳转到第三方URL，通过code换取网页授权access_token
    $get_token_url = 'https://api.weixin.qq.com/sns/oauth2/access_token?appid='.$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_SSL_VERIFYPEER, FALSE);
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
    $res = curl_exec($ch);
    curl_close($ch);
    $json_obj = json_decode($res,true);

    //3.刷新access_token（如果需要）
    $refresh_token = $json_obj['refresh_token'];
    $refresh_token_url = 'https://api.weixin.qq.com/sns/oauth2/refresh_token?appid='.$appid.'&grant_type=refresh_token&refresh_token='.$refresh_token;

    $ch = curl_init();
    curl_setopt($ch,CURLOPT_URL,$refresh_token_url);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
    $res = curl_exec($ch);
    curl_close($ch);
    $json_obj = json_decode($res,true);
    
    //4.根据openid和access_token拉取用户信息(需scope为 snsapi_userinfo)
    $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_SSL_VERIFYPEER, FALSE);
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
    $res = curl_exec($ch);
    curl_close($ch);
    $user_obj = json_decode($res,true);

    return $user_obj;
}

标签：微信公众平台  微信授权  微信开发  微信OAUTH2  微信网页授权  网页授权