Android(安卓)USB Host 使用详解（U盘）（三）
16lz
2021-01-25
Android USB Host使用详解之三：U盘操作实例
U盘命令传输流程参看：U盘bulk-only传输文档
Android中，在USB Host Mode下，U盘可以使用的传输数据（或命令）的函数有
bulkTransfer(UsbEndpoint endpoint, byte[] buffer,int length, int timeout)controlTransfer(int requestType, int request, int value, int index, byte[] buffer, int length, int timeout) controlTransfer()用于传输控制命令（控制端点），包括reset和get max lnu等命令。
下面U盘操作实例进行讲解：
1）布局文件
2）AndroidManifest.xml和device_filter.xml
<?xml version="1.0" encoding="utf-8"?> <?xml version="1.0" encoding="utf-8"?> 3）成员变量和控件初始化
private final String TAG = "++MainActivity++";private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";private Button mBtnReset;private Button mBtnGetMaxLnu;private Button mBtnSendCommand;private TextView mTvInfo;private UsbManager mUsbManager;private UsbDevice mUsbDevice;private UsbEndpoint mEndpointIn;private UsbEndpoint mEndpointOut;private UsbDeviceConnection mConnection = null;private final int mVendorID = 3544;private final int mProductID = 8199;private boolean mDetachedRegistered = false; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mBtnReset = (Button)findViewById(R.id.btn_reset); mBtnGetMaxLnu = (Button)findViewById(R.id.btn_get_max_lnu); mBtnSendCommand = (Button)findViewById(R.id.btn_send_command); mTvInfo = (TextView)findViewById(R.id.tv_info); mBtnReset.setOnClickListener(this); mBtnGetMaxLnu.setOnClickListener(this); mBtnSendCommand.setOnClickListener(this); mUsbManager = (UsbManager)getSystemService(Context.USB_SERVICE); }@Overrideprotected void onResume() {super.onResume();// 获取启动Activity的USB设备Intent intent = getIntent();String action = intent.getAction(); mUsbDevice = null;if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action)) {mUsbDevice = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);if(mVendorID != mUsbDevice.getVendorId() || mProductID != mUsbDevice.getProductId()) {mUsbDevice = null;}} if(mUsbDevice == null) { refreshDevice(); }if(mUsbDevice == null) { // 插入设备自动启动应用程序,自动获取获取permissionLog.d(TAG, "Please insert USB flash disk!");// 手机请使用ToastToast.makeText(this, "Please insert USB flash disk!", Toast.LENGTH_SHORT).show();finish();return;} // 判断是否拥有权限if(!mUsbManager.hasPermission(mUsbDevice)) {PendingIntent permissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0); IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION); registerReceiver(mPermissionReceiver, filter); mUsbManager.requestPermission(mUsbDevice, permissionIntent); } else { Log.d(TAG, "Correct device!"); Toast.makeText(MainActivity.this, "Correct device!", Toast.LENGTH_SHORT).show(); makeConnection(); } registerReceiver(usbDetachedReceiver, usbDetachedFilter); // 注册弹出通知 mDetachedRegistered = true;}5）refreshDevice()
// 启动程序前已经插入了设备,需要从设备列表中获取private void refreshDevice() {HashMap deviceList = mUsbManager.getDeviceList();Iterator deviceIterator = deviceList.values().iterator();while(deviceIterator.hasNext()){ mUsbDevice = deviceIterator.next(); if(mVendorID == mUsbDevice.getVendorId() && mProductID == mUsbDevice.getProductId()) { break; } else { mUsbDevice = null; }}} private IntentFilter usbDetachedFilter = new IntentFilter(UsbManager.ACTION_USB_DEVICE_DETACHED); private BroadcastReceiver usbDetachedReceiver = new BroadcastReceiver() {@Overridepublic void onReceive(Context context, Intent intent) {UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);if(device != null) {// 确保弹出的设备为指定的if(mVendorID == device.getVendorId() && mProductID == device.getProductId()) { mUsbDevice = null; finish();}}} }; private void makeConnection() { if(mUsbDevice == null) {Log.d(TAG, "Please insert USB flash disk!");Toast.makeText(this, "Please insert USB flash disk!", Toast.LENGTH_SHORT).show(); finish();return;} // U盘接口个数为1if(mUsbDevice.getInterfaceCount() != 1) {Log.d(TAG, "Not a USB flash disk!");Toast.makeText(this, "Not a USB flash disk!", Toast.LENGTH_SHORT).show();finish();return;}UsbInterface intf = mUsbDevice.getInterface(0);// U盘接口0可获取的端点数为2if(intf.getEndpointCount() != 2) {Log.d(TAG, "Not a USB flash disk!");Toast.makeText(this, "Not a USB flash disk!", Toast.LENGTH_SHORT).show();finish();return;} else {mEndpointIn = intf.getEndpoint(0); // Bulk-In端点mEndpointOut = intf.getEndpoint(1); // Bulk_Out端点}if (mUsbDevice != null) { UsbDeviceConnection connection = mUsbManager.openDevice(mUsbDevice); if (connection != null && connection.claimInterface(intf, true)) { Log.d(TAG, "Make connection succeeded!"); Toast.makeText(this, "Make connection succeeded!", Toast.LENGTH_SHORT).show(); mConnection = connection; } else { Log.d(TAG, "Make connection failed!"); Toast.makeText(this, "Make connection failed!", Toast.LENGTH_SHORT).show(); mConnection = null; finish(); } }}@Overridepublic void onClick(View v) {switch(v.getId()) {case R.id.btn_reset :reset();break;case R.id.btn_get_max_lnu :getMaxLnu();break;case R.id.btn_send_command :sendCommand();break;default :break;}}private void reset() {synchronized (this) { if (mConnection != null) { String str = mTvInfo.getText().toString(); // 复位命令的设置有USB Mass Storage的定义文档给出 int result = mConnection.controlTransfer(0x21, 0xFF, 0x00, 0x00, null, 0, 1000); if(result < 0) { // result<0说明发送失败 Log.d(TAG, "Send reset command failed!"); str += "Send reset command failed!\n"; } else { Log.d(TAG, "Send reset command succeeded!"); str += "Send reset command succeeded!\n"; } mTvInfo.setText(str); } }}10）getMaxLnu()获取最大的LNU
private void getMaxLnu() {synchronized (this) { if (mConnection != null) { String str = mTvInfo.getText().toString(); // 接收的数据只有1个字节 byte[] message = new byte[1]; // 获取最大LUN命令的设置由USB Mass Storage的定义文档给出 int result = mConnection.controlTransfer(0xA1, 0xFE, 0x00, 0x00, message, 1, 1000); if(result < 0) { Log.d(TAG, "Get max lnu failed!"); str += "Get max lnu failed!\n"; } else { Log.d(TAG, "Get max lnu succeeded!"); str += "Get max lnu succeeded!\nMax LNU : "; for(int i=0; i11）sendCommand()发送read format capacities命令
private void sendCommand() {String str = mTvInfo.getText().toString();byte[] cmd = new byte[] {(byte) 0x55, (byte) 0x53, (byte) 0x42, (byte) 0x43, // 固定值(byte) 0x28, (byte) 0xe8, (byte) 0x3e, (byte) 0xfe, // 自定义,与返回的CSW中的值是一样的(byte) 0x00, (byte) 0x02, (byte) 0x00, (byte) 0x00, // 传输数据长度为512字节(byte) 0x80, // 传入数据(byte) 0x00, // LNU为0,则设为0(byte) 0x01, // 命令长度为1(byte) 0x23, (byte) 0x00, (byte) 0x00, (byte) 0x00, // READ FORMAT CAPACITIES,后面的0x00皆被忽略(byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,(byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,(byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00};int result = mConnection.bulkTransfer(mEndpointOut, cmd, cmd.length, 1000);if(result < 0) { Log.d(TAG, "Send command failed!");str += "Send command failed!\n";} else {Log.d(TAG, "Send command succeeded!");str += "Send command succeeded!\n";}byte[] message = new byte[24];// 需要足够的长度接收数据result = mConnection.bulkTransfer(mEndpointIn, message, message.length, 1000);if(result < 0) { Log.d(TAG, "Receive message failed!");str += "Receive message failed!\n";} else {Log.d(TAG, "Receive message succeeded!");str += "Receive message succeeded!\nFormat capacities : \n";for(int i=0; i到这里就不得不提一下U盘发送命令的顺序
以Android手机和U盘举例，首先准备工作做好（已建立连接，bulk-in和bulk-out端点），然后Android手机发送一个CBW命令给U盘，告诉U盘要做什么：
（1）如果是发送数据给U盘，那么U盘准备好接收数据，紧接着Android手机发送数据，U盘接收数据后，返回一个CSW给Android手机，告诉接收数据是否成功，这种情况，对于开发者来说，首先发送CBW命令，判断是否发送成功，如果发送成功，紧接着发送数据（注意时间），发送数据后接收CSW，判断是否成功.......
（2）如果是要从U盘获取数据，那么U盘准备好数据发送给Android手机，Android手机从bulk-in端点接收数据，然后接收U盘发送CSW。
（3）如果是纯命令，即不用发数据，那么Android手机就接收CSW响应。
上面为先发送一个read format capacities的命令，然后接收format capacities，最后接收CSW。（没讲清楚，敬请原谅！）
最后来看一下结果吧：
接收的数据皆以16进制的形式给出，至于format capacities结果怎么计算的，我也没搞明白，我的U盘是4GB的（如果大神知道，告诉小弟呗），最后的CSW的值的前八个字节与CBW的前八个一样的，后面的请看文章开头给出的参考文档。
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