微信 Ｏauth 回调域名和使用域名不一样的使用。

wechat_oauth.php

<?php
$appid = APPID;
$appkey = APPKEY;
$redirect_url = urlencode(REDIRECT_URL);//可以为跳板url，然后跳板url跳到这里来。域名可以不一样。
$scope = "snsapi_userinfo";//snsapi_userinfo //这个可以不用关注;
$state = "";
if(isset($_GET['code'])) {
    $code = $_GET['code'];
    $api_url = "https://api.weixin.qq.com/sns/oauth2/access_token?appid={$appid}&secret={$appkey}&code={$code}&grant_type=authorization_code";
    $data_str = get($api_url);
    $data = json_decode($data_str, true);
    var_dump($data);
} else {
    $oauth_url = "https://open.weixin.qq.com/connect/oauth2/authorize?appid={$appid}&redirect_uri={$redirect_url}&response_type=code&scope={$scope}&state={$state}#wechat_redirect";
    header("location: {$oauth_url}");
}

function get($url) {
    $curl =  curl_init($url);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_TIMEOUT, 2);
    return curl_exec($curl);
}

wechat_redirect.php

<?php
$back_url = BACKURL; // oauth 所在的 URL
if(isset($_GET['code'])) {
   $code = $_GET['code'];
   $state = $_GET['state'];
   $url = "{$back_url}?code={$code}&state={$state}";
   header("location: {$url}");

} else {
    header("HTTP/1.1 403  Forbidden");
    echo "403 Forbidden";
}