预检响应中的 Access-Control-Allow-Headers 不允许请求标头字段 Access-Control-Allow-Headers

Question

我正在尝试从跨域创建登录页面但我无法解决问题，错误是：

XMLHttpRequest 无法加载 http://localhost/testing/resp.php。预检响应中的 Access-Control-Allow-Headers 不允许请求标头字段 Access-Control-Allow-Headers。

我的 Javascript 代码是：

$('#login').click(function(){
		var username = $('#uname').val();
		var password = $('#pass').val();
		var result = $('.result');
		result.text('loading....');

		if (username != '' && password !=''){
			var urltopass = 'action=login&username='+username+'&password='+password;
			$.ajax({
				type: 'POST',
				data: urltopass,
				headers: {"Access-Control-Allow-Headers": "Content-Type"},
				url: 'http://localhost/testing/resp.php',
				crossDomain: true,
				cache: false,
				success: function(responseText){
					console.log(responseText);
					if(responseText== "0"){
						result.text('incorrect login information');
					} else if (responseText == "1"){
						window.location="http://localhost/testing/home.php";
					} else{
						alert('error in sql query \n' + responseText);
					}
				}
			});
		} else return false;
	});

http://localhost/testing/resp.php 的 PHP 代码：

<?php
	include "db.php"; //Connecting to database

	if (!isset($_SERVER['HTTP_ORIGIN'])) {
		echo "This is not cross-domain request";
    exit;
}
	header("Access-Control-Allow-Origin: *");
	header("Access-Control-Allow-Credentials: true");
	header("Access-Control-Allow-Methods: POST, GET, OPTIONS");
	header("Access-Control-Allow-Headers: Content-Type, Authorization, X-Requested-With");
	header('P3P: CP="CAO PSA OUR"'); // Makes IE to support cookies
	header("Content-Type: application/json; charset=utf-8");

	if (isset($_POST['action']) && $_POST['action'] == 'login'){
		$uname = $_POST['username'];
		$pass = $_POST['password'];

		$sql = "SELECT * FROM loginajax WHERE username='$uname' AND password='$pass'";
	
		$rs=$conn->query($sql);

		if (mysqli_num_rows($rs) <= 0){
			echo "0";
		} else {
			echo "1";
		}
		
	} else echo "this is not Login";

?>

Answer 1

删除这个：

headers: {"Access-Control-Allow-Headers": "Content-Type"},

来自您的 jQuery.ajax 调用。

服务器以Access-Control-Allow-Headers 标头响应，客户端不会将其发送到服务器。

客户端发送Access-Control-Request-Headers 以请求允许某些标头，服务器以Access-Control-Allow-Headers 响应，其中列出了其将允许的实际标头。客户端不会要求允许哪些标头。