在我的应用程序中使用USB主机模式，在我的用例中提供有关连接的USB大容量存储设备的信息说Usb Flash Drive。现在我需要在连接的闪存驱动器上创建一个文件并将一些数据保存在文件。到目前为止，我发现连接到设备如下，
MainActivity.java
public class MainActivity extends AppCompatActivity {
private static final String TAG = MainActivity.class.getSimpleName();
private Button mCheckForDevice;
private TextView mDeviceInfo;
private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
private PendingIntent mPermissionIntent;
private UsbManager mUsbManager;
private UsbDevice mDeviceFound;
private UsbDeviceConnection mConnection;
private UsbInterface mUsbInterface = null;
private UsbEndpoint mInputEndpoint = null;
private UsbEndpoint mOutputEndpoint = null;
@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mCheckForDevice = (Button) findViewById(R.id.check);
mDeviceInfo = (TextView) findViewById(R.id.deviceInfo);
count=0;
mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
final HashMap<String, UsbDevice> deviceList = mUsbManager.getDeviceList();
Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
registerReceiver(mUsbReceiver, filter);
while (deviceIterator.hasNext()) {
final UsbDevice device = deviceIterator.next();
mDeviceFound = device;
i += "\n" +
"DeviceID: " + device.getDeviceId() + "\n" +
"DeviceName: " + device.getDeviceName() + "\n" +
"VendorID: " + device.getVendorId() + "\n" +
"ProductID: " + device.getProductId() + "\n" +
"Serial Number: " + device.getSerialNumber() + "\n";
}
mCheckForDevice.setOnClickListener(new View.OnClickListener() {
@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
@Override
public void onClick(View v) {
if(deviceList.size() > 0){
checkInfo(mDeviceFound);
}else{
Toast.makeText(getApplicationContext(), "No device found", Toast.LENGTH_SHORT).show();
}
}
});
}
String i = "";
private int count ;
private void checkInfo(UsbDevice device) {
count++;
if(count == 1) {
mUsbManager.requestPermission(device, mPermissionIntent);
mDeviceInfo.setText(i);
} else
Toast.makeText(this, "Already connected", Toast.LENGTH_SHORT).show();
}
@Override
protected void onPause() {
super.onPause();
count=0;
try {
unregisterReceiver(mUsbReceiver);
}catch (Exception e){
e.printStackTrace();
}
}
private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// Toast.makeText(context, "onReceive", Toast.LENGTH_SHORT).show(); writeToFile("onReceive");
if (ACTION_USB_PERMISSION.equals(action)) {
synchronized (this) {
UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
Toast.makeText(context, "Permission Granted", Toast.LENGTH_SHORT).show();
connectUsb(device);
} else {
Log.d(TAG, "permission denied for device " + device);
Toast.makeText(context, "permission denied for device" + device, Toast.LENGTH_SHORT).show();
}
}
}
}
};
private void connectUsb(UsbDevice device) {
if(device != null){
for(int i=0;i<device.getInterfaceCount();i++){
mUsbInterface = device.getInterface(i);
UsbEndpoint tOut = null;
UsbEndpoint tIn = null;
int usbEndPointCount = mUsbInterface.getEndpointCount();
if(usbEndPointCount >=2){
for(int j =0;j<usbEndPointCount;j++){
if(mUsbInterface.getEndpoint(j).getType() == UsbConstants.USB_ENDPOINT_XFER_BULK){
if(mUsbInterface.getEndpoint(j).getDirection() == UsbConstants.USB_DIR_OUT){
tOut = mUsbInterface.getEndpoint(j);
}else if(mUsbInterface.getEndpoint(j).getDirection() == UsbConstants.USB_DIR_IN){
tIn = mUsbInterface.getEndpoint(j);
}
}
}
if(tIn!=null & tOut !=null){
mInputEndpoint = tIn;
mOutputEndpoint = tOut;
}
}
}
mConnection = mUsbManager.openDevice(device);
if (mConnection.claimInterface(mUsbInterface, true)) {
Toast.makeText(this, "Connected to device", Toast.LENGTH_SHORT).show();
String msg = "Hello world";
byte[] byteArray = msg.getBytes();
int dataTransfered = mConnection.bulkTransfer(mOutputEndpoint,byteArray,byteArray.length, 0);
int controlTransfer = mConnection.controlTransfer( UsbConstants.USB_DIR_OUT, 1,0,0,byteArray,byteArray.length,0);
Toast.makeText(this, "controlTransfer " +controlTransfer, Toast.LENGTH_SHORT).show();
} else {
Log.i(TAG, "Could not connect!");
Toast.makeText(this, "Could not connect", Toast.LENGTH_SHORT).show();
}
}else{
Toast.makeText(this, "Null", Toast.LENGTH_SHORT).show();
}
}
activity_main.xml中
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/check"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Search for devices "
android:textColor="@color/black"
android:textSize="15sp" />
<TextView
android:id="@+id/deviceInfo"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_below="@+id/check"
android:layout_marginTop="14dp"
android:textColor="@color/black"
android:textSize="15sp" />
</RelativeLayout>
在上面的示例中，我尝试将String值发送到连接的设备，返回的int值是发送的字符数。但是这个信息存储在连接设备上的位置我的意思是位置？
一旦建立与设备的连接，是否有办法在连接的设备上创建文件？相关博客文章的链接很有帮助。
我在堆栈上找到this，但解决方案没有任何帮助。
感谢任何帮助。谢谢。
答案 0 :(得分：3)
您正在搜索批量端点，这意味着您正尝试使用BBB进行扇区读/写（请参阅大规模存储类BBB的USB规范）。
Now I need to create a file on the connected flash drive and save some data in the file.
使用端点执行扇区读/写，但您必须在其上编写文件系统驱动程序（如FAT32或EXT4等）。
文件创建是文件系统操作，而不是扇区级读/写。
Is there a way to create a file on connected device once the connection to the device is established?
您必须使用Android文件系统安装工具，然后使用通用文件API创建文件。
答案 1 :(得分：0)
在考虑了所有建议的想法之后，我找到了可以接受的解决方案。使用 UsbHost Api获取设备相关信息然后 使用存储访问框架执行归档操作。