关于session不能使用的问题

                                             laraval关于session失效问题

Kernel.php中开启Session

```

    protected $middleware = [

        \App\Http\Middleware\CheckForMaintenanceMode::class,

        \Illuminate\Foundation\Http\Middleware\ValidatePostSize::class,

        \App\Http\Middleware\TrimStrings::class,

        \Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class,

        \App\Http\Middleware\TrustProxies::class,

         \Illuminate\Session\Middleware\StartSession::class,

}

```

切忌是先运行构造方法在走session 这种顺序！！！