開始在 Android 應用程式中使用 Firebase 雲端通訊

// Declare the launcher at the top of your Activity/Fragment:
private val requestPermissionLauncher = registerForActivityResult(
    ActivityResultContracts.RequestPermission(),
) { isGranted: Boolean ->
    if (isGranted) {
        // FCM SDK (and your app) can post notifications.
    } else {
        // TODO: Inform user that that your app will not show notifications.
    }
}

private fun askNotificationPermission() {
    // This is only necessary for API level >= 33 (TIRAMISU)
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.POST_NOTIFICATIONS) ==
            PackageManager.PERMISSION_GRANTED
        ) {
            // FCM SDK (and your app) can post notifications.
        } else if (shouldShowRequestPermissionRationale(Manifest.permission.POST_NOTIFICATIONS)) {
            // TODO: display an educational UI explaining to the user the features that will be enabled
            //       by them granting the POST_NOTIFICATION permission. This UI should provide the user
            //       "OK" and "No thanks" buttons. If the user selects "OK," directly request the permission.
            //       If the user selects "No thanks," allow the user to continue without notifications.
        } else {
            // Directly ask for the permission
            requestPermissionLauncher.launch(Manifest.permission.POST_NOTIFICATIONS)
        }
    }
}
MainActivity.kt

// Declare the launcher at the top of your Activity/Fragment:
private final ActivityResultLauncher<String> requestPermissionLauncher =
        registerForActivityResult(new ActivityResultContracts.RequestPermission(), isGranted -> {
            if (isGranted) {
                // FCM SDK (and your app) can post notifications.
            } else {
                // TODO: Inform user that that your app will not show notifications.
            }
        });

private void askNotificationPermission() {
    // This is only necessary for API level >= 33 (TIRAMISU)
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.POST_NOTIFICATIONS) ==
                PackageManager.PERMISSION_GRANTED) {
            // FCM SDK (and your app) can post notifications.
        } else if (shouldShowRequestPermissionRationale(Manifest.permission.POST_NOTIFICATIONS)) {
            // TODO: display an educational UI explaining to the user the features that will be enabled
            //       by them granting the POST_NOTIFICATION permission. This UI should provide the user
            //       "OK" and "No thanks" buttons. If the user selects "OK," directly request the permission.
            //       If the user selects "No thanks," allow the user to continue without notifications.
        } else {
            // Directly ask for the permission
            requestPermissionLauncher.launch(Manifest.permission.POST_NOTIFICATIONS);
        }
    }
}
MainActivity.java

  /**
   * There are three scenarios when `onRegistered` is called:
   * 1) Every time a manual `register()` call finishes successfully
   * 2) Whenever the FID is changed and the app is re-registered with FCM via the new FID.
   * 3) Automatically on app startup or routine sync when auto-initialization is enabled.
   * Under #2, there are three scenarios when the existing FID is changed:
   * A) App is restored to a new device
   * B) User uninstalls/reinstalls the app
   * C) User clears app data
   */
  override fun onRegistered(installationId: String) {
      Log.d(TAG, "Registered installation ID: $installationId")

      // Send the Firebase Installation ID to your app server.
      sendRegistrationToServer(installationId)
  }
    

  /**
   * There are three scenarios when `onRegistered` is called:
   * 1) Every time a manual `register()` call finishes successfully
   * 2) Whenever the FID is changed and the app is re-registered with FCM via the new FID
   * 3) Automatically on app startup or routine sync when auto-initialization is enabled.
   * Under #2, there are three scenarios when the existing FID is changed:
   * A) App is restored to a new device
   * B) User uninstalls/reinstalls the app
   * C) User clears app data
   */
  @Override
  public void onRegistered(@NonNull String installationId) {
      Log.d(TAG, "Registered installation ID: " + installationId);

      // Send the Firebase Installation ID to your app server.
      sendRegistrationToServer(installationId);
  }
    

  // Trigger manual registration if auto-initialization is turned off.
  // Consider calling this every time the app starts to guarantee sync status.
  FirebaseMessaging.getInstance().register()
      .addOnCompleteListener(this) { task ->
        if (!task.isSuccessful()) {
          // Registration failed. Consider retrying the registration with exponential backoff.
          Log.w(TAG, "Failed to register with Firebase Cloud Messaging", task.exception)
        }
        // Success! The Firebase Installation ID can be used to target messages to this app
        // instance and will be delivered asynchronously to your `onRegistered()` callback.
      }
    

  // Trigger manual registration if auto-initialization is turned off.
  // Consider calling this every time the app starts to guarantee sync status.
  FirebaseMessaging.getInstance().register()
      .addOnCompleteListener(task -> {
        if (!task.isSuccessful()) {
          // Registration failed. Consider retrying the registration with exponential backoff.
          Log.w(TAG, "Failed to register with Firebase Cloud Messaging", task.exception)
        }
        // Success! The Firebase Installation ID can be used to target messages to this app
        // instance and will be delivered asynchronously to your `onRegistered()` callback.
      });
    

FirebaseMessaging.getInstance().token.addOnCompleteListener(OnCompleteListener { task ->
    if (!task.isSuccessful) {
        Log.w(TAG, "Fetching FCM registration token failed", task.exception)
        return@OnCompleteListener
    }

    // Get new FCM registration token
    val token = task.result

    // Log and toast
    val msg = getString(R.string.msg_token_fmt, token)
    Log.d(TAG, msg)
    Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
})

FirebaseMessaging.getInstance().getToken()
    .addOnCompleteListener(new OnCompleteListener<String>() {
        @Override
        public void onComplete(@NonNull Task<String> task) {
          if (!task.isSuccessful()) {
            Log.w(TAG, "Fetching FCM registration token failed", task.getException());
            return;
          }

          // Get new FCM registration token
          String token = task.getResult();

          // Log and toast
          String msg = getString(R.string.msg_token_fmt, token);
          Log.d(TAG, msg);
          Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();
        }
    });

/**
 * Called if the FCM registration token is updated. This may occur if the security of
 * the previous token had been compromised. Note that this is called when the
 * FCM registration token is initially generated so this is where you would retrieve the token.
 */
override fun onNewToken(token: String) {
    Log.d(TAG, "Refreshed token: $token")

    // If you want to send messages to this application instance or
    // manage this apps subscriptions on the server side, send the
    // FCM registration token to your app server.
    sendRegistrationToServer(token)
}
MyFirebaseMessagingService.kt

/**
 * There are two scenarios when onNewToken is called:
 * 1) When a new token is generated on initial app startup
 * 2) Whenever an existing token is changed
 * Under #2, there are three scenarios when the existing token is changed:
 * A) App is restored to a new device
 * B) User uninstalls/reinstalls the app
 * C) User clears app data
 */
@Override
public void onNewToken(@NonNull String token) {
    Log.d(TAG, "Refreshed token: " + token);

    // If you want to send messages to this application instance or
    // manage this apps subscriptions on the server side, send the
    // FCM registration token to your app server.
    sendRegistrationToServer(token);
}
MyFirebaseMessagingService.java

Firebase.messaging.isAutoInitEnabled = true
MainActivity.kt

FirebaseMessaging.getInstance().setAutoInitEnabled(true);
MainActivity.java