cors跨域资源共享---解决前后端跨域问题

Cross-Origin Resource Sharing (CORS) ，定义了在跨域访问资源时浏览器和服务器之间如何通信。CORS背后的基本思想是使用自定义的HTTP头部允许浏览器和服务器相互了解对方，从而决定请求或响应成功与否。

解决方法：

①后端加响应头

header("Access-Control-Allow-Origin: *");
header(‘Access-Control-Allow-Credentials: true‘);
header(‘Access-Control-Max-Age: 86400‘);    // cache for 1 day
// header("Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS");
// 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, PUT, DELETE, OPTIONS");
    if (isset($_SERVER[‘HTTP_ACCESS_CONTROL_REQUEST_HEADERS‘]))
        header("Access-Control-Allow-Headers: {$_SERVER[‘HTTP_ACCESS_CONTROL_REQUEST_HEADERS‘]}");
}

②设置前端ajax请求参数