如何通过 java 服务器使用 FCM 向 android 设备发送推送通知？

Question

我已经通过 java 服务器代码编写了使用 fcm 发送通知的代码。但它抛出异常 服务器返回 HTTP 响应代码：URL 500：https://fcm.googleapis.com/fcm/send

public static void pushFCMNotification(String userDeviceIdKey) throws     Exception{

    String authKey = AUTH_KEY_FCM;   // You FCM AUTH key
    String FMCurl = API_URL_FCM;     

    URL url = new URL(FMCurl);
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();

    conn.setUseCaches(false);
    conn.setDoInput(true);
    conn.setDoOutput(true);

    conn.setRequestMethod("POST");
    conn.setRequestProperty("Authorization","key="+authKey);
    conn.setRequestProperty("Content-Type","application/json");

    JSONObject json = new JSONObject();
    json.put("to",userDeviceIdKey.trim());
    JSONObject info = new JSONObject();
    info.put("title", "Notificatoin Title");   // Notification title
    info.put("body", "Hello Test notification"); // Notification body
    json.put("notification", info);

    OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
    wr.write(json.toString());
        wr.flush();
        wr.close();

        int responseCode = conn.getResponseCode();
        System.out.println("\nSending 'POST' request to URL : " + url);
        System.out.println("Post parameters : " + json);
        System.out.println("Response Code : " + responseCode);

        BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();

        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();


    /*OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
    wr.write(json.toString());
    wr.flush();
    conn.getInputStream();*/
    }

Answer 1

根据官方文档：

Errors in the 500-599 range (such as 500 or 503) indicate that there was an internal error in the FCM connection server while trying to process the request, or that the server is temporarily unavailable (for example, because of timeouts). Sender must retry later, honoring any Retry-After header included in the response. Application servers must implement exponential back-off.

来源：https://firebase.google.com/docs/cloud-messaging/http-server-ref#interpret-downstream

但是，请确保 JSON 请求的格式正确。尝试使用 json.toString() 更新您的问题，并使用 Checking the validity of a server key

中描述的过程检查您的 API 密钥是否仍然有效

如何通过 java 服务器使用 FCM 向 android 设备发送推送通知？

how to send push notification to the android device using FCM by java server?

java

exception

firebase-cloud-messaging