Go to cloud Messaging select:  Server key



function sendGCM($message, $deviceToken) {

    $url = 'https://fcm.googleapis.com/fcm/send';
    $fields = array (
            'registration_ids' => array (
                $id
            ),
            'data' => array (
                "title" =>  "Notification title",
                "body" =>  $message,
            )
    );
    $fields = json_encode ( $fields );
    $headers = array (
        'Authorization: key=' . "YOUR_SERVER_KEY",
        'Content-Type: application/json'
    );
    $ch = curl_init ();
    curl_setopt ( $ch, CURLOPT_URL, $url );
    curl_setopt ( $ch, CURLOPT_POST, true );
    curl_setopt ( $ch, CURLOPT_HTTPHEADER, $headers );
    curl_setopt ( $ch, CURLOPT_RETURNTRANSFER, true );
    curl_setopt ( $ch, CURLOPT_POSTFIELDS, $fields );
    $result = curl_exec ( $ch );
    echo $result;

    curl_close ($ch);
}

使用Firebase Console可以根据应用程序包向所有用户发送消息。但对于CURL或PHP API，这是不可能的。

通过API可以向指定的设备ID或订阅的用户发送通知给选定的主题或订阅的主题用户。

Get a view on following link. It will help you.
https://firebase.google.com/docs/cloud-messaging/send-message

Firebase云消息传递有一个服务器端api，您可以调用它来发送消息。见https://firebase.google.com/docs/cloud-messaging/server。

发送消息可以像使用curl调用HTTP端点一样简单。看到https://firebase.google.com/docs/cloud-messaging/server implementing-http-connection-server-protocol

curl -X POST --header "Authorization: key=<API_ACCESS_KEY>" \
    --Header "Content-Type: application/json" \
    https://fcm.googleapis.com/fcm/send \
    -d "{\"to\":\"<YOUR_DEVICE_ID_TOKEN>\",\"notification\":{\"title\":\"Hello\",\"body\":\"Yellow\"}}"

您可以在任何环境中使用所有这些REST API，但是这里列出的许多平台都有专门的所谓管理sdk。

下面是我使用CURL的项目中的工作代码。

<?PHP
//Avoid keys confusions!
//firebase Cloud Messaging have 3 different keys: 
//API_KEY, SERVER_KEY and PUSH_KEY ... here we need SERVER_KEY

// SERVER access key from Google firebase Console    
define( 'SERVER_ACCESS_KEY', 'YOUR-SERVER-ACCESS-KEY-GOES-HERE' );


 $registrationIds = array( $_GET['id'] );

  // prep the bundle
 $msg = array
 (
   'message'    => 'here is a message. message',
    'title'     => 'This is a title. title',
    'subtitle'  => 'This is a subtitle. subtitle',
    'tickerText'    => 'Ticker text here...Ticker text here...Ticker text here',
    'vibrate'   => 1,
    'sound'     => 1,
    'largeIcon' => 'large_icon',
    'smallIcon' => 'small_icon'
 );

 $fields = array
 (
    // use this to method if want to send to topics
    // 'to' => 'topics/all'
    'registration_ids'  => $registrationIds,
     'notification'         => $msg
 );

 $headers = array
 (
    'Authorization: key=' . SERVER_ACCESS_KEY,
    'Content-Type: application/json'
 );

 $ch = curl_init();
 curl_setopt( $ch,CURLOPT_URL, 'https://fcm.googleapis.com/fcm/send' );
 curl_setopt( $ch,CURLOPT_POST, true );
 curl_setopt( $ch,CURLOPT_HTTPHEADER, $headers );
 curl_setopt( $ch,CURLOPT_RETURNTRANSFER, true );
 curl_setopt( $ch,CURLOPT_SSL_VERIFYPEER, false );
 curl_setopt( $ch,CURLOPT_POSTFIELDS, json_encode( $fields ) );
 $result = curl_exec($ch );
 curl_close( $ch );

 echo $result;

2020年作品

$response = Http::withHeaders([
            'Content-Type' => 'application/json',
            'Authorization'=> 'key='. $token,
        ])->post($url, [
            'notification' => [
                'body' => $request->summary,
                'title' => $request->title,
                'image' => 'http://'.request()->getHttpHost().$path,
                
            ],
            'priority'=> 'high',
            'data' => [
                'click_action'=> 'FLUTTER_NOTIFICATION_CLICK',
                
                'status'=> 'done',
                
            ],
            'to' => '/topics/all'
        ]);

Go to cloud Messaging select:  Server key



function sendGCM($message, $deviceToken) {

    $url = 'https://fcm.googleapis.com/fcm/send';
    $fields = array (
            'registration_ids' => array (
                $id
            ),
            'data' => array (
                "title" =>  "Notification title",
                "body" =>  $message,
            )
    );
    $fields = json_encode ( $fields );
    $headers = array (
        'Authorization: key=' . "YOUR_SERVER_KEY",
        'Content-Type: application/json'
    );
    $ch = curl_init ();
    curl_setopt ( $ch, CURLOPT_URL, $url );
    curl_setopt ( $ch, CURLOPT_POST, true );
    curl_setopt ( $ch, CURLOPT_HTTPHEADER, $headers );
    curl_setopt ( $ch, CURLOPT_RETURNTRANSFER, true );
    curl_setopt ( $ch, CURLOPT_POSTFIELDS, $fields );
    $result = curl_exec ( $ch );
    echo $result;

    curl_close ($ch);
}