[移动开发]Android 监听USB设备插拔事件

通过注册广播的方式监听USB设备 。

广播Action

• UsbManager.ACTION_USB_DEVICE_ATTACHED
  Usb设备插入或者挂载事件通知
• UsbManager.ACTION_USB_DEVICE_DETACHED
  Usb设备拔出或者卸载时间通知

定义广播

private final BroadcastReceiver mUsbMonitorReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(final Context context, final Intent intent) {
            final String action = intent.getAction();
            if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action)) {
                final UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
                int vendorId = device.getVendorId();
                int productId = device.getProductId();
            } else if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action)) {
                final UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
                int vendorId = device.getVendorId();
                int productId = device.getProductId();
            }
        }
    };

根据Usb设备VenorId和ProductId检索被监听的Usb设备节点。

注册广播

IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
        intentFilter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);

        try {
            context.registerReceiver(mUsbMonitorReceiver, intentFilter);
        } catch (Exception e) {
            e.printStackTrace();
        }

注销广播

try {
            context.unregisterReceiver(mUsbMonitorReceiver);
        } catch (Exception e) {
            e.printStackTrace();
        }

有些系统或者设备监听不到Usb设备的插入或者挂载的事件，可通过轮询的方式根据Usb设备的节点信息（一般是VendorId和ProductId）进行检测。

根据 VendorId 和 ProductId查找Usb设备

public static UsbDevice findUsbDevice(Context context, int vendorId, int productId) {
        UsbManager usbManager = (UsbManager) context.getSystemService(Context.USB_SERVICE);
        final HashMap<String, UsbDevice> deviceList = usbManager.getDeviceList();
        if (deviceList != null) {
            final Iterator<UsbDevice> iterator = deviceList.values().iterator();
            while (iterator.hasNext()) {
                UsbDevice  device = iterator.next();
                if (device.getVendorId() == vendorId && device.getProductId() == productId) {
                    return device;
                }
            }
        }
        
        return null;
    }

开始轮询

private void startUsbMonitor() {
        mHandlerThread = new HandlerThread("UsbMonitor");
        mHandlerThread.start();
        mHandler = new Handler(mHandlerThread.getLooper()) {
            @Override
            public void handleMessage(Message msg) {
                switch (msg.what) {
                    case EVENT_CHECK_USB_DEVICE: {
                        boolean found = findUsbDevice(context, vendorId, productId) != null;
                        if (!found){
                            mHandler.sendEmptyMessageDelayed(EVENT_CHECK_USB_DEVICE, 5000);
                        } else {
                            // TODO:
                        }
                        break;
                    }
                    default:
                        break;
                }
            }
        };
        mHandler.sendEmptyMessage(EVENT_CHECK_USB_DEVICE);
    }

结束轮询

private void stopUsbMonitor() {
        if (mHandler != null) {
            mHandler.getLooper().quit();
            mHandler = null;
        }

        if (mHandlerThread != null) {
            mHandlerThread.quitSafely();
            mHandlerThread = null;
        }
    }

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