管理連線

建立連線

當找到鄰近裝置時，探索人員可以啟動連線。以下範例會在找到裝置後立即要求連線。

private final EndpointDiscoveryCallback endpointDiscoveryCallback =
    new EndpointDiscoveryCallback() {
      @Override
      public void onEndpointFound(String endpointId, DiscoveredEndpointInfo info) {
        // An endpoint was found. We request a connection to it.
        Nearby.getConnectionsClient(context)
            .requestConnection(getLocalUserName(), endpointId, connectionLifecycleCallback)
            .addOnSuccessListener(
                (Void unused) -> {
                  // We successfully requested a connection. Now both sides
                  // must accept before the connection is established.
                })
            .addOnFailureListener(
                (Exception e) -> {
                  // Nearby Connections failed to request the connection.
                });
      }

      @Override
      public void onEndpointLost(String endpointId) {
        // A previously discovered endpoint has gone away.
      }
    };

根據您的用途，您可以改為顯示已發現的項目清單來選擇要連接的裝置。

接受或拒絕連線

發現者要求與廣告客戶建立關係後，雙方透過 onConnectionInitiated() 收到連線啟動程序的通知方法 ConnectionLifecycleCallback 回呼。請注意，此回呼會傳入 startAdvertising() 探索工具的廣告客戶與 requestConnection() 但從這裡開始 API 屬於對稱式 API

現在雙方必須選擇接受或拒絕通話分別設為 acceptConnection() 或 rejectConnection()連結是只有在雙方都接受時，系統才會建立完整資料庫。如果兩個或兩者皆拒絕連線。無論您選擇哪一種，結果都會傳送到 onConnectionResult()。

下列程式碼片段說明如何實作這個回呼：

private final ConnectionLifecycleCallback connectionLifecycleCallback =
    new ConnectionLifecycleCallback() {
      @Override
      public void onConnectionInitiated(String endpointId, ConnectionInfo connectionInfo) {
        // Automatically accept the connection on both sides.
        Nearby.getConnectionsClient(context).acceptConnection(endpointId, payloadCallback);
      }

      @Override
      public void onConnectionResult(String endpointId, ConnectionResolution result) {
        switch (result.getStatus().getStatusCode()) {
          case ConnectionsStatusCodes.STATUS_OK:
            // We're connected! Can now start sending and receiving data.
            break;
          case ConnectionsStatusCodes.STATUS_CONNECTION_REJECTED:
            // The connection was rejected by one or both sides.
            break;
          case ConnectionsStatusCodes.STATUS_ERROR:
            // The connection broke before it was able to be accepted.
            break;
          default:
            // Unknown status code
        }
      }

      @Override
      public void onDisconnected(String endpointId) {
        // We've been disconnected from this endpoint. No more data can be
        // sent or received.
      }
    };

再次強調，本範例顯示雙方自動接受連線，但您可以根據自己的使用情境，以某種方式向使用者顯示這個選項。

驗證連線

要求連線時，應用程式可透過以下方式「驗證」連線：使用提供給 onConnectionInitiated() 的驗證權杖這個能讓使用者確認，所連結的是裝置。兩部裝置標有相同的符記，都是短隨機字串。驗證方式完全由您決定這通常涉及顯示並請使用者手動比較並確認類似於藍牙配對對話方塊

此程式碼範例示範了透過顯示 AlertDialog 中使用者的驗證權杖：

@Override
public void onConnectionInitiated(String endpointId, ConnectionInfo info) {
  new AlertDialog.Builder(context)
      .setTitle("Accept connection to " + info.getEndpointName())
      .setMessage("Confirm the code matches on both devices: " + info.getAuthenticationDigits())
      .setPositiveButton(
          "Accept",
          (DialogInterface dialog, int which) ->
              // The user confirmed, so we can accept the connection.
              Nearby.getConnectionsClient(context)
                  .acceptConnection(endpointId, payloadCallback))
      .setNegativeButton(
          android.R.string.cancel,
          (DialogInterface dialog, int which) ->
              // The user canceled, so we should reject the connection.
              Nearby.getConnectionsClient(context).rejectConnection(endpointId))
      .setIcon(android.R.drawable.ic_dialog_alert)
      .show();
}