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

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;

如果您正在使用PHP，我建议使用用于Firebase的PHP SDK: Firebase Admin SDK。为了一个简单的配置，您可以按照以下步骤:

从Firebase获取项目凭证json文件(初始化sdk)，并将其包含在项目中。

在项目中安装SDK。我使用composer:

composer require kreait/firebase-php ^4.35

试试SDK文档中云消息会话的任何例子:

use Kreait\Firebase;
use Kreait\Firebase\Messaging\CloudMessage;

$messaging = (new Firebase\Factory())
->withServiceAccount('/path/to/firebase_credentials.json')
->createMessaging();

$message = CloudMessage::withTarget(/* see sections below */)
    ->withNotification(Notification::create('Title', 'Body'))
    ->withData(['key' => 'value']);

$messaging->send($message);

使用curl的示例

向特定设备发送消息

要将消息发送到特定设备，请将该设置为特定应用实例的注册令牌

curl -H "Content-type: application/json" -H "Authorization:key=<Your Api key>"  -X POST -d '{ "data": { "score": "5x1","time": "15:10"},"to" : "<registration token>"}' https://fcm.googleapis.com/fcm/send

向主题发送消息

这里的主题是:/topics/foo-bar

curl -H "Content-type: application/json" -H "Authorization:key=<Your Api key>"  -X POST -d '{ "to": "/topics/foo-bar","data": { "message": "This is a Firebase Cloud Messaging Topic Message!"}}' https://fcm.googleapis.com/fcm/send

向设备组发送消息

向设备组发送消息与向单个设备发送消息非常相似。将to参数设置为设备组的唯一通知键

curl -H "Content-type: application/json" -H "Authorization:key=<Your Api key>"  -X POST -d '{"to": "<aUniqueKey>","data": {"hello": "This is a Firebase Cloud Messaging Device Group Message!"}}' https://fcm.googleapis.com/fcm/send

使用服务API的示例

火网址:https://fcm.googleapis.com/fcm/send

头

Content-type: application/json
Authorization:key=<Your Api key>

请求方式:POST

请求体

发送到特定设备的消息

{
  "data": {
    "score": "5x1",
    "time": "15:10"
  },
  "to": "<registration token>"
}

主题的消息

{
  "to": "/topics/foo-bar",
  "data": {
    "message": "This is a Firebase Cloud Messaging Topic Message!"
  }
}

给设备组的消息

{
  "to": "<aUniqueKey>",
  "data": {
    "hello": "This is a Firebase Cloud Messaging Device Group Message!"
  }
}

或者你可以使用Firebase的云功能，对我来说，这是实现推送通知的更简单的方法。 重火力点/ functions-samples