授权：浏览器在请求头中发送用户名和密码，授权没有发送或不符合，服务器返回“401 Unauthorized"响应。认证：检查$_SERVER['PHP_AUTH_USER'] $_SERVER['PHP_AUTH_PW']

          header('WWW-Authenticate:Basic realm="Top Secret Files"');

          header('HTTP/1.0/ 401 Unauthorized');

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