谢谢大家，我发现了我的问题.从这篇文章复制并粘贴代码PHP之后，我决定对其进行优化-我将所有语句放入if METHOD == OPTIONS .这是错误的.

Thank you all, guys, I found my problem. After I copy-paste code PHP-from this post, I decided to optimize it - I placed all statements into if METHOD == OPTIONS. This is fault.

标头Access-Control-Allow-Origin不仅应返回给OPTIONS请求，还应返回.

Header Access-Control-Allow-Origin should be returned not only for OPTIONS request.

我更新的代码工作正常:

My updated code works fine:

if (isset($_SERVER["HTTP_ORIGIN"])) {
    header("Access-Control-Allow-Origin: {$_SERVER["HTTP_ORIGIN"]}");
}

if ($_SERVER["REQUEST_METHOD"] == "OPTIONS") {
    if (isset($_SERVER["HTTP_ACCESS_CONTROL_REQUEST_METHOD"])) {
        header("Access-Control-Allow-Methods: GET, POST, OPTIONS");
    }

    if (isset($_SERVER["HTTP_ACCESS_CONTROL_REQUEST_HEADERS"])) {
        header("Access-Control-Allow-Headers: {$_SERVER["HTTP_ACCESS_CONTROL_REQUEST_HEADERS"]}");
    }

    exit(0);
}

感谢@Patrick Evans的第二条评论，但它已经被删除=)

Thanks to @Patrick Evans second comment, but it's already deleted =)