重庆免费做网站,男生和女生做污的事情免费网站,徐州泉山建设局网站,建设外贸企业网站当使用 Android 设备作为 USB 配件时#xff0c;可以使用 Android 提供的 USB Accessory API 来进行 USB 通信。以下是一个简单的 Android USB 配件模式的通信例子。在本例中#xff0c;我们将接收连接到 Android 设备的 USB 主机发送的数据并向 USB 主机发送响应。
首先可以使用 Android 提供的 USB Accessory API 来进行 USB 通信。以下是一个简单的 Android USB 配件模式的通信例子。在本例中我们将接收连接到 Android 设备的 USB 主机发送的数据并向 USB 主机发送响应。
首先在 AndroidManifest.xml 文件中添加以下权限
uses-feature android:nameandroid.hardware.usb.accessory /
uses-permission android:nameandroid.permission.ACCESSORY /
uses-permission android:nameandroid.permission.WAKE_LOCK /接着在 res/xml 文件夹中创建一个名为 accessory_filter.xml 的文件用于指定 USB 配件的属性及其应用程序的信息。以下是示例文件的内容
?xml version1.0 encodingutf-8?
resourcesusb-accessory modelAndroid Accessory manufacturerAndroid version1.0 /
/resources在 Activity 中添加以下代码
private static final String TAG USBAccessoryDemo;private static final String ACTION_USB_PERMISSION com.example.android.usbaccessory.USB_PERMISSION;
private static final int TIMEOUT 1000;
private static final int MAX_PACKET_SIZE 16384;private UsbAccessory mAccessory;
private UsbManager mUsbManager;
private PendingIntent mPermissionIntent;
private boolean mPermissionRequestPending;
private UsbAccessoryConnection mAccessoryConnection;Override
protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mUsbManager (UsbManager) getSystemService(Context.USB_SERVICE);mPermissionIntent PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);IntentFilter filter new IntentFilter(ACTION_USB_PERMISSION);registerReceiver(mUsbReceiver, filter);HashMapString, UsbAccessory accessoryList mUsbManager.getAccessoryList();if (accessoryList ! null) {UsbAccessory accessory accessoryList.get(0);if (accessory ! null) {if (mUsbManager.hasPermission(accessory)) {openAccessory(accessory);} else {mUsbManager.requestPermission(accessory, mPermissionIntent);mPermissionRequestPending true;}} else {Log.d(TAG, accessory is null);}} else {Log.d(TAG, accessoryList is null);}
}Override
public void onResume() {super.onResume();if (mAccessoryConnection ! null mAccessoryConnection.isOpen()) {mAccessoryConnection.startReading();}
}Override
public void onPause() {super.onPause();if (mAccessoryConnection ! null mAccessoryConnection.isOpen()) {mAccessoryConnection.stopReading();}
}Override
protected void onDestroy() {super.onDestroy();unregisterReceiver(mUsbReceiver);if (mAccessoryConnection ! null mAccessoryConnection.isOpen()) {mAccessoryConnection.close();}
}private final BroadcastReceiver mUsbReceiver new BroadcastReceiver() {public void onReceive(Context context, Intent intent) {String action intent.getAction();if (ACTION_USB_PERMISSION.equals(action)) {synchronized (this) {UsbAccessory accessory (UsbAccessory) intent.getParcelableExtra(UsbManager.EXTRA_ACCESSORY);if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {openAccessory(accessory);} else {Log.d(TAG, permission denied for accessory accessory);}mPermissionRequestPending false;}}}
};private void openAccessory(UsbAccessory accessory) {mAccessoryConnection new UsbAccessoryConnection(this, accessory);mAccessoryConnection.open();
}private class UsbAccessoryConnection implements Runnable {private final UsbManager mUsbManager;private final UsbAccessory mAccessory;private UsbDeviceConnection mConnection;private UsbEndpoint mInEndpoint;private UsbEndpoint mOutEndpoint;private InputStream mInputStream;private OutputStream mOutputStream;private Thread mReadThread;private boolean mIsRunning;public UsbAccessoryConnection(Context context, UsbAccessory accessory) {mUsbManager (UsbManager) context.getSystemService(Context.USB_SERVICE);mAccessory accessory;}public void open() {mConnection mUsbManager.openAccessory(mAccessory);if (mConnection ! null) {mInEndpoint mAccessory.getEndpoint(0);mOutEndpoint mAccessory.getEndpoint(1);mInputStream new BufferedInputStream(mConnection.openInputStream(mInEndpoint), MAX_PACKET_SIZE);mOutputStream new BufferedOutputStream(mConnection.openOutputStream(mOutEndpoint), MAX_PACKET_SIZE);mIsRunning true;mReadThread new Thread(this);mReadThread.start();} else {Log.d(TAG, openAccessory failed);}}public void close() {mIsRunning false;if (mReadThread ! null) {try {mReadThread.join();} catch (InterruptedException e) {e.printStackTrace();}}if (mInputStream ! null) {try {mInputStream.close();} catch (IOException e) {e.printStackTrace();}}if (mOutputStream ! null) {try {mOutputStream.close();} catch (IOException e) {e.printStackTrace();}}if (mConnection ! null) {mConnection.close();}}public boolean isOpen() {return mConnection ! null;}public void startReading() {if (mReadThread ! null !mReadThread.isAlive()) {mIsRunning true;mReadThread new Thread(this);mReadThread.start();}}public void stopReading() {mIsRunning false;}public void write(byte[] data) {if (mOutputStream ! null) {try {mOutputStream.write(data);mOutputStream.flush();} catch (IOException e) {e.printStackTrace();}}}Overridepublic void run() {byte[] buffer new byte[MAX_PACKET_SIZE];while (mIsRunning) {try {int len mInputStream.read(buffer);if (len 0) {final String receivedData new String(buffer, 0, len);runOnUiThread(new Runnable() {Overridepublic void run() {// 处理接收到的数据}});}} catch (IOException e) {e.printStackTrace();mIsRunning false;}}}
}在上面的代码中我们首先检查是否已连接 USB 配件。如果已连接则尝试打开连接。如果没有权限则请求权限。如果没有可用的 USB 配件则在日志中记录错误消息。
在打开连接后我们创建一个 UsbAccessoryConnection 对象并使用 open() 方法打开连接。在 open() 方法中我们获取连接的 UsbDeviceConnection 对象并使用它来获取读取和写入数据的输入/输出流。我们还启动了一个读线程该线程不断地从输入流中读取数据并将其传递给主线程以进行处理。
最后我们可以使用 write() 方法向 USB 主机发送数据并使用 close() 方法关闭连接。
以上就是Android usb 配件模式下的示例在实际的开发过程中会比较复杂但原理基本类似。如果文档对你有帮助欢迎点赞、收藏和评论谢谢
