parking_manage_system/app/Events/SendAnnouncement.php

<?php

namespace App\Events;

use Illuminate\Broadcasting\Channel;
use Illuminate\Broadcasting\InteractsWithSockets;
use Illuminate\Contracts\Broadcasting\ShouldBroadcast;
use Illuminate\Foundation\Events\Dispatchable;
use Illuminate\Queue\SerializesModels;

class SendAnnouncement implements ShouldBroadcast
{
    use Dispatchable, InteractsWithSockets, SerializesModels;

    public $message;

    public function __construct($message)
    {
        $this->message = $message;
    }

    /**
     * 指定事件广播到的频道
     */
    public function broadcastOn(): array
    {
        return [
            new Channel('chat'),  // 公共频道
        ];
    }

    /**
     * 可选：自定义广播数据
     */
    public function broadcastWith(): array
    {
        return [
            'message' => $this->message,
            'time' => now()->toDateTimeString(),
        ];
    }
}