使用蓝牙将两台 Android 设备与第三台设备配对

Question

我正在做一个 Android 应用程序，我需要 2 台或更多台设备才能通过蓝牙连接到一台设备。以对等形式将两个设备连接在一起的代码有效，但是当我尝试连接另一个设备时，我收到一个 IOException 说“连接被拒绝”，因为 Socket 已关闭，因此无法完成配对。错误如下所示。

Socket closed. Unable to complete pairing.
java.io.IOException: Connection refused
    at android.bluetooth.BluetoothSocket.connectNative(Native Method)
    at android.bluetooth.BluetoothSocket.connect(BluetoothSocket.java:216)
    at com.ablueworld.androidgridcomputingframework.BluetoothManager$ConnectAsyncTask.doInBackground(BluetoothManager.java:270)
    at com.ablueworld.androidgridcomputingframework.BluetoothManager$ConnectAsyncTask.doInBackground(BluetoothManager.java:1)
    at android.os.AsyncTask$2.call(AsyncTask.java:264)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
    at java.lang.Thread.run(Thread.java:856)
Could not connect to this device

然后我读到它需要为每个连接使用不同的 UUID，对吗？无论如何，我已经编写了如下所示的代码，为每个新连接从数组中获取不同的 UUID。

    // Unique UUID for this application
    private static int indexUUID = 0;
    private static final UUID[] MY_UUID_SECURE = {UUID.fromString("98b97e6b-62ff-4a36-a81b-82256fd1d168"),
                                                  UUID.fromString("98b97e6b-62ff-4a36-a81b-82256fd1d169"),
                                                  UUID.fromString("98b97e6b-62ff-4a36-a81b-82256fd1d170"),
                                                  UUID.fromString("98b97e6b-62ff-4a36-a81b-82256fd1d171"),
                                                  UUID.fromString("98b97e6b-62ff-4a36-a81b-82256fd1d172")};
    private static final String NAME_SECURE = "GridFrameworkSecure";

    /**
     * Method to connect securely to Bluetooth device using it's MAC address
     * @param macAddress valid Bluetooth MAC address
     */
    public boolean connectSecurelyToDevice(BluetoothAdapter btAdapter, String macAddress){
        BluetoothDevice device = btAdapter.getRemoteDevice(macAddress);
        ConnectAsyncTask connectTask = new ConnectAsyncTask();
        BluetoothSocket deviceSocket = null;
        try {
            deviceSocket = connectTask.execute(device).get();
        } catch (InterruptedException e) {
            e.printStackTrace();
            return false;
        } catch (ExecutionException e) {
            e.printStackTrace();
            return false;
        }
        if(deviceSocket!=null){
            if(serverBluetoothNode==null){
                try {
                    serverBluetoothNode = new BluetoothNode(deviceSocket);
                    Log.i("bluetooth manager", "You are now a slave node.");


                    return true;
                } catch (IOException e) {
                    e.printStackTrace();
                    return false;
                }
            } else {
                Log.e("bluetooth manager", "You already have a master.");
                return false;
            }
        } else return false;
    }

    /**
     * Method to allow this Bluetooth device to accept connection from another Bluetooth device
     */
    public void allowSecureConnectionFromRemoteDevice(BluetoothAdapter btAdapter){
        AcceptConnectionAsyncTask acceptTask = new AcceptConnectionAsyncTask();
        acceptTask.execute(btAdapter);
    }

    private class ConnectAsyncTask extends AsyncTask<BluetoothDevice, Void, BluetoothSocket> {

        @Override
        protected BluetoothSocket doInBackground(BluetoothDevice... params) {
            BluetoothDevice device = params[0];
            BluetoothSocket socket = null;

            // Get a BluetoothSocket for a connection with the
            // given BluetoothDevice
            try {
                socket = device.createRfcommSocketToServiceRecord(MY_UUID_SECURE[indexUUID]);
            } catch (IOException e) {
                Log.e("Bluetooth Pairing", "create() failed", e);
            }

            Log.i("Bluetooth Pairing", "BEGIN ConnectThread SocketType: Secure");

            // Make a connection to the BluetoothSocket
            try {
                // This is a blocking call and will only return on a
                // successful connection or an exception
                socket.connect();
                Log.i("bluetooth manager", "You have connected a slave node to this one.");

                return socket;
            } catch (IOException e) {
                Log.e("Bluetooth Pairing", "Socket closed. Unable to complete pairing.", e);
                // Close the socket
                try {
                    socket.close();
                    indexUUID++;
                } catch (IOException e2) {
                    Log.e("Bluetooth Pairing", "unable to close() socket during connection failure", e2);
                }
            }

            return null;
        }

    }

    private class AcceptConnectionAsyncTask extends AsyncTask<BluetoothAdapter, Void, Void> {

        @Override
        protected Void doInBackground(BluetoothAdapter... params) {
            BluetoothServerSocket serverSocket = null;
            String socketType = "Secure";

            // Create a new listening server socket
            try {
                serverSocket = params[0].listenUsingRfcommWithServiceRecord(NAME_SECURE, MY_UUID_SECURE[indexUUID]);
            } catch (IOException e) {
                Log.e("Accept Bluetooth Pairing Thread", "Socket Type: " + socketType + "listen() failed", e);
                indexUUID++;
            }

            Log.d("Accept Bluetooth Pairing Thread", "Socket Type: " + socketType +
                    "BEGIN mAcceptThread" + this);

            BluetoothSocket socket = null;

            // Listen to the server socket if we're not connected
            while (true) { //mState != STATE_CONNECTED) {
                try {
                    // This is a blocking call and will only return on a
                    // successful connection or an exception
                    socket = serverSocket.accept();
                    Log.i("Slave", "server socket found");                    

                    // If a connection was accepted
                    if (socket != null) {
                        BluetoothNode node = null;
                        try {
                            node = new BluetoothNode(socket);
                            Log.i("connected to", node.getDeviceInformation());
                            slaveBluetoothNodes.add(node);

                            indexUUID++;
                    serverSocket = params[0].listenUsingRfcommWithServiceRecord(NAME_SECURE, MY_UUID_SECURE[indexUUID]);

                        } catch (IOException e) {
                            e.printStackTrace();

                            indexUUID++;
                            serverSocket = params[0].listenUsingRfcommWithServiceRecord(NAME_SECURE, MY_UUID_SECURE[indexUUID]);
                        }
                    }
                } catch (IOException e) {
                    Log.e("Accept Bluetooth Pairing Thread", "Socket Type: " + socketType + "accept() failed", e);

                    try {
                        indexUUID++;
                        serverSocket = params[0].listenUsingRfcommWithServiceRecord(NAME_SECURE, MY_UUID_SECURE[indexUUID]);
                    } catch (IOException e1) {
                        Log.e("Accept Bluetooth Pairing Thread", "Socket Type: " + socketType + "listen() failed", e1);
                    }
                }


            }
        }

    }

但即便如此，我在尝试连接到已经与第二台设备的蓝牙连接正常工作的第三台手机上遇到不同的错误，如下所示。

 Socket closed. Unable to complete pairing.
 java.io.IOException: Service discovery failed
    at android.bluetooth.BluetoothSocket$SdpHelper.doSdp(BluetoothSocket.java:406)
    at android.bluetooth.BluetoothSocket.connect(BluetoothSocket.java:217)
    at com.ablueworld.androidgridcomputingframework.BluetoothManager$ConnectAsyncTask.doInBackground(BluetoothManager.java:270)
    at com.ablueworld.androidgridcomputingframework.BluetoothManager$ConnectAsyncTask.doInBackground(BluetoothManager.java:1)
    at android.os.AsyncTask$2.call(AsyncTask.java:185)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
    at java.util.concurrent.FutureTask.run(FutureTask.java:138)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
    at java.lang.Thread.run(Thread.java:1019)
 Could not connect to this device

谁能帮忙解决这个问题？谢谢。

Answer 1

在创建套接字连接之前，尝试在您的 BluetoothAdapter 上调用 cancelDiscovery()。这可能会解决您收到的java.io.IOException: Service discovery failed 的问题。

Answer 2

我已经找到了解决问题的方法。

在监听然后建立连接的方法中，我是这样写的：

UUID[] MY_UUID_SECURE = {UUID.fromString("98b97e6b-62ff-4a36-a81b-82256fd1d168"),
                                                  UUID.fromString("98b97e6b-62ff-4a36-a81b-82256fd1d169"),
                                                  UUID.fromString("98b97e6b-62ff-4a36-a81b-82256fd1d170"),
                                                  UUID.fromString("98b97e6b-62ff-4a36-a81b-82256fd1d171"),
                                                  UUID.fromString("98b97e6b-62ff-4a36-a81b-82256fd1d172")};

BluetoothServerSocket serverSocket = null;
            BluetoothSocket socket = null;

            try {
                // Listen for all UUIDs in array
                for (int i = 0; i < MY_UUID_SECURE.length; i++) {
                    serverSocket = btAdapter.listenUsingRfcommWithServiceRecord(NAME_SECURE, MY_UUID_SECURE[i]);
                    socket = serverSocket.accept();
                    if (socket != null) {
                        BluetoothNode node = null;
                        node = new BluetoothNode(socket);
                        Log.i("connected to", node.getDeviceInformation());
                        slaveBluetoothNodes.add(node);

                        // add node to database
                        databaseManager.insertToGridTree(node.getDeviceAddress(), "slave", "active", node.getDeviceName());
                    }                       
                }
            } catch (IOException e) {
                Log.e("Accept Bluetooth Pairing Thread", "accept() failed", e);
            }

以及从设备连接主设备的方法：

    BluetoothDevice device = params[0];
    BluetoothSocket socket = null;

    Log.i("Bluetooth Pairing", "BEGIN ConnectThread SocketType: Secure");

    // Get a BluetoothSocket for a connection with the
    // given BluetoothDevice
    for(int i=0; i<MY_UUID_SECURE.length; i++){
        try {
            socket = device.createRfcommSocketToServiceRecord(MY_UUID_SECURE[i]);
            // This is a blocking call and will only return on a
            // successful connection or an exception
            socket.connect();
            Log.i("bluetooth manager", "You have connected a slave node to this one.");

            return socket;
        } catch (IOException e) {
            Log.e("Bluetooth Pairing", "create() failed", e);
            Log.i("Bluetooth Pairing", "trying another UUID");
            try {
                socket.close();
            } catch (IOException e2) {
                Log.e("Bluetooth Pairing", "unable to close() socket during connection failure", e2);
            }
        }
    }

这个项目帮我解决了这个问题：https://github.com/polyclef/BluetoothChatMulti

希望这对遇到同样问题的人有所帮助。 :)