Allow No 'Access-Control-Allow-Origin' header is present

后台使用laravel框架，前端请求数据报错 Allow No 'Access-Control-Allow-Origin' header is present 

解决办法：

一、在App\Http\Middleware目录下新建Cors.php

<?php

namespace App\Http\Middleware;

use Closure;

class Cors
{
/**
* Handle an incoming request.
*
* @param  \Illuminate\Http\Request  $request
* @param  \Closure  $next
* @return mixed
*/
public function handle($request, Closure $next)
{
$response = $next($request);

$headers = config('star.cors', []);

$response->headers->add($headers);

return $response;
}
}

二、在项目配置文件config\star.php 文件中新增跨域的配置信息

/*
|--------------------------------------------------------------------------
| CORS跨域配置
|--------------------------------------------------------------------------
|
*/
'cors' => [
'Access-Control-Allow-Origin' => '*',
'Access-Control-Allow-Credentials' => 'true',
'Access-Control-Allow-Headers' => 'Origin, X-Requested-With, Content-Type, Accept, Cache-Control, Authorization',
'Access-Control-Allow-Methods' => 'HEAD, GET, POST, PUT, PATCH, DELETE, OPTIONS, TRACE',
],

三、讲Cros.php中间件加入到App\Http\Kernel.php中

protected $middleware = [
\Illuminate\Foundation\Http\Middleware\CheckForMaintenanceMode::class,
\App\Http\Middleware\Cors::class,
];

以上是正常请求，为了处理异常请求的返回，在App\Exceptions\Hander.php中增加header信息

$headers = config('star.cors', []);

$response->headers->add($headers);