如何以编程方式判断是否已连接蓝牙设备? [英] How to programmatically tell if a Bluetooth device is connected?

问题描述

我了解如何获取已配对设备的列表，但是如何知道它们是否已连接?

I understand how to get a list of paired devices but how can I tell if they are connected?

因为我在手机的蓝牙设备列表中看到了它们，并指出了它们的连接状态，所以这一定是可能的.

It must be possible since I see them listed in my phone's Bluetooth device list and it states their connection status.

推荐答案

向您的AndroidManifest添加蓝牙权限，

Add bluetooth permission to your AndroidManifest,

<uses-permission android:name="android.permission.BLUETOOTH" />

然后使用意图过滤器收听ACTION_ACL_CONNECTED，ACTION_ACL_DISCONNECT_REQUESTED和ACTION_ACL_DISCONNECTED广播:

Then use intent filters to listen to the ACTION_ACL_CONNECTED, ACTION_ACL_DISCONNECT_REQUESTED, and ACTION_ACL_DISCONNECTED broadcasts:

public void onCreate() {
    ...
    IntentFilter filter = new IntentFilter();
    filter.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
    filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED);
    filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
    this.registerReceiver(mReceiver, filter);
}

//The BroadcastReceiver that listens for bluetooth broadcasts
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

        if (BluetoothDevice.ACTION_FOUND.equals(action)) {
           ... //Device found
        }
        else if (BluetoothDevice.ACTION_ACL_CONNECTED.equals(action)) {
           ... //Device is now connected
        }
        else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
           ... //Done searching
        }
        else if (BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED.equals(action)) {
           ... //Device is about to disconnect
        }
        else if (BluetoothDevice.ACTION_ACL_DISCONNECTED.equals(action)) {
           ... //Device has disconnected
        }           
    }
};

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一些注意事项:

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A few notes:

• 在应用程序启动时无法检索已连接设备的列表.蓝牙API不允许您查询，而是允许您收听更改.
• 解决上述问题的麻烦方法是检索所有已知/已配对设备的列表...然后尝试连接到每个设备(以确定是否已连接).
• 或者，您可以让后台服务监视Bluetooth API并将设备状态写入磁盘，以供您的应用程序以后使用.

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