Android listenUsingRfcommWithServiceRecord（…）返回null

我的蓝牙服务器在尝试创建蓝牙服务器套接字时崩溃。 我已经在谷歌上搜索了很多，找到了几个我尝试过的答案，但都没用。 我在几个不同的设备上尝试了这段代码，但同样的错误随处可见

...
private class AcceptThread extends Thread {
    private final BluetoothServerSocket mmServerSocket;

    public AcceptThread() {
        // Use a temporary object that is later assigned to mmServerSocket,
        // because mmServerSocket is final
        BluetoothServerSocket tmp = null;
        try {
            // MY_UUID is the app's UUID string, also used by the client code
            tmp = mBluetoothAdapter.listenUsingRfcommWithServiceRecord(Var.SERVICE_NAME, UUID.fromString("a70aec2c-19e4-4804-8e3c-557de4e3f558"));
        } catch (IOException e) {
            e.printStackTrace();
        }
        mmServerSocket = tmp;
    }

    public void run() {
        BluetoothSocket socket = null;
        // Keep listening until exception occurs or a socket is returned
        while (true) {
            try {
                socket = mmServerSocket.accept();
            } catch (IOException e) {
                break;
            }
...

错误消息：

08-01 16:14:48.361: E/AndroidRuntime(32417): FATAL EXCEPTION: Thread-8045
08-01 16:14:48.361: E/AndroidRuntime(32417): Process: ... .bluetoothserver, PID: 32417
08-01 16:14:48.361: E/AndroidRuntime(32417): java.lang.NullPointerException
08-01 16:14:48.361: E/AndroidRuntime(32417):    at ... .bluetoothserver.communication.BluetoothChat$AcceptThread.run(BluetoothChat.java:103)

08-01 16:14:48.731: E/BluetoothSocket(32417): bindListen, fail to get port number, exception: java.io.IOException: read failed, socket might closed or timeout, read ret: -1

这里怎么了？下一行中的tmp为空：

tmp = mBluetoothAdapter.listenUsingRfcommWithServiceRecord(Var.SERVICE_NAME, UUID.fromString("a70aec2c-19e4-4804-8e3c-557de4e3f558"));

---

listenUsingRfcommWithServiceRecord失败并引发IOException，IOException已被忽略，AcceptThread已启动。mmServerSocket已设置为空

这应该可以解决这个问题：

private class Server_Connect_Thread extends Thread {
private final BluetoothServerSocket mmServerSocket;
private boolean running = true;
public Server_Connect_Thread() {
BluetoothServerSocket tmp = null;
try {
    tmp = bluetooth_adapter.listenUsingRfcommWithServiceRecord("NAME", uuid);
} catch (IOException e) {
    bluetooth_show_message("Bluetooth Error! listenUsingRfcommWithServiceRecord failed. Reason:" + e);
    running = false;
}
mmServerSocket = tmp;
}

public void run() {
while (running) {
    try {
        socket = mmServerSocket.accept();
    } catch (IOException e) {
        bluetooth_show_message("Bluetooth Error! Accepting a connection failed. Reason:" + e);
        break;
    }
...
}

您遇到的IOException经常发生，例如，当其他设备无法及时连接时，或者您连接到错误的蓝牙设备时。就我而言，那是我邻居的电视机