XMLHttpRequest否'訪問控制允許來源'

Question

我試圖使用ionic 2和angular 2進行登錄訪問。每當按正確的詳細信息時，都會出現此錯誤

 XMLHttpRequest cannot load http://adirzoari.16mb.com/newapi.php. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8100' is therefore not allowed access.' 

我還在網站上閱讀了類似的問題，但仍然沒有任何解決方案。

這是我登錄的php文件

        <?php
    header("Access-Control-Allow-Origin: *");
    header("Content-Type: application/json; charset=UTF-8");
    $conn = new mysqli("mysql.hostinger.co.uk", "a", "1234", "appd");

        //http://stackoverflow.com/questions/18382740/cors-not-working-php
        if (isset($_SERVER['HTTP_ORIGIN'])) {
            header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
            header('Access-Control-Allow-Credentials: true');
            header('Access-Control-Max-Age: 86400');    // cache for 1 day
        }

        // Access-Control headers are received during OPTIONS requests
        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);
        }


        //http://stackoverflow.com/questions/15485354/angular-http-post-to-php-and-undefined
        $postdata = file_get_contents("php://input");
        if (isset($postdata)) {
            $request = json_decode($postdata);
            $username = $request->username;
            $password = $request->password;
                    $data = array();

            if ($password != "" && $username != "") {

            //echo "Server returns: " . $username . "Password is :" . $password;

                /*$arr=array();

                $st="select * from subnews order by SubID desc limit 10";
                $qr=$conn->query($st);
                while($row=$qr->fetch_assoc()){
                    $arr[]=$row;
                }
                echo json_encode($arr);*/

                $sel="SELECT id FROM users WHERE username='$username' AND password='$password'";
                $result=$conn->query($sel);
                $numrow=$result->num_rows;
                if($numrow == 1){ 
                            include 'tokengenerate.php'; 
                            $token=generateRandomString();    
                            $update="update users set token='$token' where username='$username' AND password='$password'";    
                            $qr=$conn->query($update);
                            if($qr){

                               $sel="SELECT id FROM users WHERE username='$username' AND password='$password'";
                               $query=$conn->query($sel);
                               while($row=$query->fetch_assoc(){
                                     $data[]=array(
                                     "name"->$row['username'],
                                     "token"->$row['token']
                                   );
                               echo json_encode($data);
                               }

                               } 
                }

            }
            else {
                header('HTTP/1.1 401 Unauthorized', true, 401);
            }
        }
        else {
            echo "Not called properly with username parameter!";
        }
    ?>  

Answer 1

當您將XmlHttpRequest從您的域發送到另一個域並且瀏覽器由於出於安全目的的交叉源而被阻止時，可能會導致此問題。

如果您不請求其他檢查，或者不是從非安全URL到安全URL的請求，例如從http URL到https的請求，這也可能導致該錯誤。