Android USB 通信开发

Android USB 通信开发主要涉及两种模式：主机模式(Host Mode)和配件模式(Accessory Mode)。以下是开发USB通信应用的关键知识点和步骤。

1. 基本概念

主机模式(Host Mode)

• Android设备作为USB主机，控制连接的USB设备

• 需要设备支持USB主机功能(通常需要OTG支持)

配件模式(Accessory Mode)

• Android设备作为USB配件被其他主机控制

• 需要设备支持USB配件模式

2. 开发准备

清单文件配置

<!-- 声明USB主机功能 -->
<uses-feature android:name="android.hardware.usb.host" /><!-- 声明USB配件功能（如果需要） -->
<uses-feature android:name="android.hardware.usb.accessory" /><!-- 添加必要的权限 -->
<uses-permission android:name="android.permission.USB_PERMISSION" />

3. USB主机模式开发

发现连接的USB设备

UsbManager usbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
HashMap<String, UsbDevice> deviceList = usbManager.getDeviceList();

请求设备权限

private static final String ACTION_USB_PERMISSION = "com.example.USB_PERMISSION";PendingIntent permissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), PendingIntent.FLAG_IMMUTABLE);IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
registerReceiver(usbReceiver, filter);usbManager.requestPermission(device, permissionIntent);

广播接收器处理权限结果

private final BroadcastReceiver usbReceiver = new BroadcastReceiver() {public void onReceive(Context context, Intent intent) {String action = intent.getAction();if (ACTION_USB_PERMISSION.equals(action)) {synchronized (this) {UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {if(device != null){// 权限已授予，可以通信openDevice(device);}} else {Log.d(TAG, "权限被拒绝 for device " + device);}}}}
};

打开设备并通信

private void openDevice(UsbDevice device) {UsbInterface intf = device.getInterface(0);UsbEndpoint endpoint = intf.getEndpoint(0);UsbDeviceConnection connection = usbManager.openDevice(device);if (connection == null) return;connection.claimInterface(intf, true);// 发送数据byte[] sendData = "Hello".getBytes();int sent = connection.bulkTransfer(endpoint, sendData, sendData.length, 0);// 接收数据byte[] receiveData = new byte[64];int received = connection.bulkTransfer(endpoint, receiveData, receiveData.length, 0);
}

4. USB配件模式开发

清单文件配置

<activity ...><intent-filter><action android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED" /></intent-filter><meta-data android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED"android:resource="@xml/accessory_filter" />
</activity>

配件过滤器(xml/accessory_filter.xml)

<resources><usb-accessory manufacturer="YourCompany" model="YourModel" version="1.0" />
</resources>

检测配件连接

UsbManager usbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
UsbAccessory[] accessoryList = usbManager.getAccessoryList();if (accessoryList != null && accessoryList.length > 0) {UsbAccessory accessory = accessoryList[0];openAccessory(accessory);
}

打开配件通信

private void openAccessory(UsbAccessory accessory) {ParcelFileDescriptor fd = usbManager.openAccessory(accessory);if (fd != null) {FileDescriptor fileDescriptor = fd.getFileDescriptor();FileInputStream inputStream = new FileInputStream(fileDescriptor);FileOutputStream outputStream = new FileOutputStream(fileDescriptor);// 现在可以通过输入输出流进行通信}
}

5. 常见问题

1. 权限问题：确保正确请求和处理USB权限

2. 设备兼容性：并非所有Android设备都支持USB主机模式

3. 线程阻塞：USB通信可能阻塞UI线程，建议在后台线程进行

4. 连接稳定性：处理USB设备插拔事件

6. 高级主题

• USB串口通信：使用CDC(Communication Device Class)协议

• HID设备通信：与键盘、鼠标等HID设备交互

• 同步通信：使用控制传输(Control Transfer)和中断传输(Interrupt Transfer)

7. 推荐库

• usb-serial-for-android：简化USB串口通信

• libusb-android：提供更底层的USB访问

开发时请参考Android官方USB文档获取最新信息。