How to prevent name caching and detect bluetooth name changes on discovery

问题

I'm writing an Android app which receives information from a Bluetooth device. Our client has suggested that the Bluetooth device (which they produce) will change its name depending on certain conditions - for the simplest example its name will sometimes be "xxx-ON" and sometimes "xxx-OFF". My app is just supposed to seek this BT transmitter (I use BluetoothAdapter.startDiscovery() ) and do different things depending on the name it finds. I am NOT pairing with the Bluetooth device (though I suppose it might be possible, the app is supposed to eventually work with multiple Android devices and multiple BT transmitters so I'm not sure it would be a good idea).

My code works fine to detect BT devices and find their names. Also, if the device goes off, I can detect the next time I seek, that it is not there. But it seems that if it is there and it changes name, I pick up the old name - presumably it is cached somewhere. Even if the bluetooth device goes off, and we notice that, the next time I detect it, I still see the old name.

I found this issue in Google Code: here but it was unclear to me even how to use the workaround given ("try to connect"). Has anyone done this and had any luck? Can you share code?

Is there a simple way to just delete the cached names and search again so I always find the newest names? Even a non-simple way would be good (I am writing for a rooted device).

Thanks

回答1:

I would suggest 'fetchUuidsWithSdp()'. It's significance is that, unlike the similar getUuids() method, fetchUuidsWithSdp causes the device to update cached information about the remote device. And I believe this includes the remote name as well as the SPD.

Note that both the methods I mentioned are hidden prior to 4.0.3, so your code would look l ike this:

public static void startServiceDiscovery( BluetoothDevice device ) {
    // Need to use reflection prior to API 15
    Class cl = null;
    try {
        cl = Class.forName("android.bluetooth.BluetoothDevice");
    } catch( ClassNotFoundException exc ) {
        Log.e(CTAG, "android.bluetooth.BluetoothDevice not found." );
    }
    if (null != cl) {
        Class[] param = {};
        Method method = null;
        try {
            method = cl.getMethod("fetchUuidsWithSdp", param);
        } catch( NoSuchMethodException exc ) {
            Log.e(CTAG, "fetchUuidsWithSdp not found." );
        }
        if (null != method) {
            Object[] args = {};
            try {
                method.invoke(device, args);
            } catch (Exception exc) {
                Log.e(CTAG, "Failed to invoke fetchUuidsWithSdp method." );
            }               
        }
    }
}

You'll then need to listen for the BluetoothDevice.ACTION_NAME_CHANGED intent, and extract BluetoothDevice.EXTRA_NAME from it.

Let me know if that helps.

来源：https://stackoverflow.com/questions/10171843/how-to-prevent-name-caching-and-detect-bluetooth-name-changes-on-discovery

标签

android

caching

bluetooth

names