Android USB Host 使用详解（U盘）（三）
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
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);
} @Override
protected 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permission
Log.d(TAG, "Please insert USB flash disk!"); // 手机请使用Toast
Toast.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() {
@Override
public 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1
if(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2
if(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();
}
}
} @Override
public 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。