如何防止名称缓存并检测发现时的蓝牙名称更改 [英] How to prevent name caching and detect bluetooth name changes on discovery

问题描述

我正在编写一个从蓝牙设备接收信息的 Android 应用程序.我们的客户建议蓝牙设备(他们生产的)将根据某些条件更改其名称 - 最简单的例子，其名称有时是xxx-ON"，有时是xxx-OFF".我的应用程序只是应该寻找这个 BT 发射器(我使用 BluetoothAdapter.startDiscovery() )并根据它找到的名称做不同的事情.我没有与蓝牙设备配对(虽然我认为这可能是可能的，但该应用程序最终应该可以与多个 Android 设备和多个 BT 发射器配合使用，所以我不确定这是否是一个好主意).

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).

我的代码可以很好地检测 BT 设备并找到它们的名称.此外，如果设备关闭，我下次搜索时可以检测到它不在那里.但似乎如果它在那里并且更改了名称，我会选择旧名称 - 大概它被缓存在某个地方.即使蓝牙设备关闭，我们注意到，下次我检测到它时，我仍然看到旧名称.

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.

我在 Google 代码中发现了这个问题:这里但是我什至不清楚如何使用给定的解决方法(尝试连接").有没有人做过这个并且有任何运气?可以分享代码吗?

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?

是否有一种简单的方法可以删除缓存的名称并再次搜索，以便我始终找到最新的名称?即使是一种不简单的方法也会很好(我正在为有根设备编写).

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).

谢谢

推荐答案

我建议使用 'fetchUuidsWithSdp()'.重要的是，与类似的 getUuids() 方法不同，fetchUuidsWithSdp 会导致设备更新有关远程设备的缓存信息.我相信这包括远程名称以及 SPD.

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.

注意我提到的两个方法在 4.0.3 之前都是隐藏的，所以你的代码看起来像这样:

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." );
            }               
        }
    }
}

然后您需要监听 BluetoothDevice.ACTION_NAME_CHANGED 意图，并从中提取 BluetoothDevice.EXTRA_NAME.

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

如果这有帮助，请告诉我.

Let me know if that helps.

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