Android检测外接USB设备的几种方法

柔光的暖阳◎ 2022-06-07 05:49 958阅读 0赞

遇到需要监测USB键盘的问题，搜集了一些方法做总结。

1. 使用BroadcastReceiver监听系统广播

private void detectUsbWithBroadcast() {
            Log.d(TAG, "listenUsb: register");
            IntentFilter filter = new IntentFilter();
            filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
            filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
            filter.addAction(UsbManager.ACTION_USB_ACCESSORY_ATTACHED);
            filter.addAction(UsbManager.ACTION_USB_ACCESSORY_DETACHED);
            filter.addAction("android.hardware.usb.action.USB_STATE");
    
            registerReceiver(mUsbStateChangeReceiver, filter);
            Log.d(TAG, "listenUsb: registered");
        }
    
        private BroadcastReceiver mUsbStateChangeReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                Log.d(TAG, "onReceive: " + intent.getAction());
            }
    
        };

2. 使用InputManager检测输入设备

private void detectUsbDeviceWithInputManager() {
            InputManager im = (InputManager) getSystemService(INPUT_SERVICE);
            int[] devices = im.getInputDeviceIds();
            for (int id : devices) {
                InputDevice device = im.getInputDevice(id);
    //            Log.d(TAG, "detectUsbDeviceWithInputManager: " + device.getName());
                //do something
            }
        }

3. 使用Configuration

private void detectUsbKeyboardWithConfig() {
            Configuration config = getResources().getConfiguration();
            if (config.keyboard == Configuration.KEYBOARD_NOKEYS) {
                Log.i(TAG, "detectUsbKeyboardWithConfig: config: no keyboard");
            } else {
                Log.i(TAG, "detectUsbKeyboardWithConfig: config: has keyboard: " + config.keyboard);
            }
        }

4. 使用UsbManager

private void detectUsbDeviceWithUsbManager() {
            HashMap<String, UsbDevice> deviceHashMap = ((UsbManager) getSystemService(USB_SERVICE)).getDeviceList();
    
            for (Map.Entry entry : deviceHashMap.entrySet()) {
                Log.d(TAG, "detectUsbDeviceWithUsbManager: " + entry.getKey() + ", " + entry.getValue());
            }
        }

5. 调用Linux命令

private void detectInputDeviceWithShell() {
            try {
                //获得外接USB输入设备的信息
                Process p = Runtime.getRuntime().exec("cat /proc/bus/input/devices");
                BufferedReader in = new BufferedReader(new InputStreamReader(p.getInputStream()));
                String line = null;
                while ((line = in.readLine()) != null) {
                    String deviceInfo = line.trim();
                    //对获取的每行的设备信息进行过滤，获得自己想要的。
    //                if (deviceInfo.contains("Name="))
                        Log.d(TAG, "detectInputDeviceWithShell: " + deviceInfo);
                }
                Log.d(TAG, "-----------------------");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

对于usb键盘，以上2、5两种方法是行之有效的，其他的并不能检测到，具体原因不明。

根据网上所说，Linux下USB设备分为字符设备（顺序访问）和块设备（随机访问），而键盘属于字符设备，U盘属于块设备，或许是因为这个原因导致二者的差别？