我正在努力使Android代码工作，可以与多个USB串行设备和Android平板电脑进行通信。为此，我使用FELHR85 https://github.com/felHR85/UsbSerial的USB串行库。
我能够一次与单个USB设备通信。但是，现在当我尝试连接并与多个USB串行设备通信时，App失败了。我使用下面的代码来测试多个设备。
public class UsbService extends Service {
public static final String ACTION_USB_READY = "com.felhr.connectivityservices.USB_READY";
public static final String ACTION_USB_ATTACHED = "android.hardware.usb.action.USB_DEVICE_ATTACHED";
public static final String ACTION_USB_DETACHED = "android.hardware.usb.action.USB_DEVICE_DETACHED";
public static final String ACTION_USB_NOT_SUPPORTED = "com.felhr.usbservice.USB_NOT_SUPPORTED";
public static final String ACTION_NO_USB = "com.felhr.usbservice.NO_USB";
public static final String ACTION_USB_PERMISSION_GRANTED = "com.felhr.usbservice.USB_PERMISSION_GRANTED";
public static final String ACTION_USB_PERMISSION_NOT_GRANTED = "com.felhr.usbservice.USB_PERMISSION_NOT_GRANTED";
public static final String ACTION_USB_DISCONNECTED = "com.felhr.usbservice.USB_DISCONNECTED";
public static final String ACTION_CDC_DRIVER_NOT_WORKING = "com.felhr.connectivityservices.ACTION_CDC_DRIVER_NOT_WORKING";
public static final String ACTION_USB_DEVICE_NOT_WORKING = "com.felhr.connectivityservices.ACTION_USB_DEVICE_NOT_WORKING";
public static final int MESSAGE_FROM_SERIAL_PORT = 0;
private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
private static int BAUD_RATE = 4800; // BaudRate. Change this value if you need
public static boolean SERVICE_CONNECTED = false;
private IBinder binder = new UsbBinder();
private Context context;
private Handler mHandler;
private UsbManager usbManager;
private UsbDevice device;
private UsbDeviceConnection connection;
private UsbSerialDevice serialPort;
private boolean serialPortConnected;
UsbInterface intf;
SessionManager sessionManager;
/*
* Data received from serial port will be received here. Just populate onReceivedData with your code
* In this particular example. byte stream is converted to String and send to UI thread to
* be treated there.
*/
private UsbSerialInterface.UsbReadCallback mCallback = new UsbSerialInterface.UsbReadCallback() {
@Override
public void onReceivedData(byte[] arg0) {
try {
String data = new String(arg0, "UTF-8");
data.concat("\0");
if (mHandler != null)
mHandler.obtainMessage(MESSAGE_FROM_SERIAL_PORT, data).sendToTarget();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
};
/*
* Different notifications from OS will be received here (USB attached, detached, permission responses...)
* About BroadcastReceiver: http://developer.android.com/reference/android/content/BroadcastReceiver.html
*/
private final BroadcastReceiver usbReceiver = new BroadcastReceiver() {
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1) @Override
public void onReceive(Context arg0, Intent arg1) {
if (arg1.getAction().equals(ACTION_USB_PERMISSION)) {
boolean granted = arg1.getExtras().getBoolean(UsbManager.EXTRA_PERMISSION_GRANTED);
if (granted) // User accepted our USB connection. Try to open the device as a serial port
{
Intent intent = new Intent(ACTION_USB_PERMISSION_GRANTED);
arg0.sendBroadcast(intent);
connection = usbManager.openDevice(device);
serialPortConnected = true;
new ConnectionThread().run();
} else // User not accepted our USB connection. Send an Intent to the Main Activity
{
Intent intent = new Intent(ACTION_USB_PERMISSION_NOT_GRANTED);
arg0.sendBroadcast(intent);
}
} else if (arg1.getAction().equals(ACTION_USB_ATTACHED)) {
if (!serialPortConnected)
findSerialPortDevice(); // A USB device has been attached. Try to open it as a Serial port
} else if (arg1.getAction().equals(ACTION_USB_DETACHED)) {
// Usb device was disconnected. send an intent to the Main Activity
if(intf != null && intf.getInterfaceClass() == UsbConstants.USB_CLASS_HID){
Intent intent = new Intent(ACTION_USB_DISCONNECTED);
arg0.sendBroadcast(intent);
serialPortConnected = false;
if(serialPort != null)
serialPort.close();
}
}
}
};
/*
* onCreate will be executed when service is started. It configures an IntentFilter to listen for
* incoming Intents (USB ATTACHED, USB DETACHED...) and it tries to open a serial port.
*/
@Override
public void onCreate() {
this.context = this;
serialPortConnected = false;
UsbService.SERVICE_CONNECTED = true;
setFilter();
sessionManager = new SessionManager(context);
usbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
findSerialPortDevice();
}
/* MUST READ about services
* http://developer.android.com/guide/components/services.html
* http://developer.android.com/guide/components/bound-services.html
*/
@Override
public IBinder onBind(Intent intent) {
return binder;
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
return Service.START_NOT_STICKY;
}
@Override
public void onDestroy() {
super.onDestroy();
UsbService.SERVICE_CONNECTED = false;
}
/*
* This function will be called from MainActivity to write data through Serial Port
*/
public void write(byte[] data) {
if (serialPort != null)
{
//Log.e("Serialport Found","Serialport Found");
serialPort.write(data);
}
//Log.e("Serialport Not Found","Serialport Not Found");
}
public void setHandler(Handler mHandler) {
this.mHandler = mHandler;
}
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1) private void findSerialPortDevice() {
// This snippet will try to open the first encountered usb device connected, excluding usb root hubs
HashMap<String, UsbDevice> usbDevices = usbManager.getDeviceList();
System.out.println("<====================== Counter Settings =========================>");
System.out.println("Counter Baudrate =============>"+sessionManager.getCOUNTER_BAUDRATE());
System.out.println("Counter DataBits =============>"+sessionManager.getCOUNTER_DATA_BITS());
System.out.println("Counter StopBits =============>"+sessionManager.getCOUNTER_STOP_BITS());
System.out.println("Counter Parity =============>"+sessionManager.getCOUNTER_PARITY());
System.out.println("Counter Flow Control =============>"+sessionManager.getCOUNTER_FLOW_CONTROL());
System.out.println("<====================== Scale Settings =========================>");
System.out.println("Scale Baudrate =============>"+sessionManager.getSCALE_BAUDRATE());
System.out.println("Scale DataBits =============>"+sessionManager.getSCALE_DATA_BITS());
System.out.println("Scale StopBits =============>"+sessionManager.getSCALE_STOP_BITS());
System.out.println("Scale Parity =============>"+sessionManager.getSCALE_PARITY());
System.out.println("Scale Flow Control =============>"+sessionManager.getSCALE_FLOW_CONTROL());
if (!usbDevices.isEmpty()) {
boolean keep = true;
for (Map.Entry<String, UsbDevice> entry : usbDevices.entrySet()) {
device = entry.getValue();
int deviceVID = device.getVendorId();
int devicePID = device.getProductId();
intf = device.getInterface(0);
if(device != null && !device.equals(""))
Utils.writeIntoFile(getBaseContext(),"device =============>"+device+"\n"+"getInterface Count =============>"+device.getInterfaceCount());
if (intf.getInterfaceClass() != UsbConstants.USB_CLASS_HID) {
if (deviceVID != 0x1d6b && (devicePID != 0x0001 || devicePID != 0x0002 || devicePID != 0x0003)) {
if(device.getDeviceName().equalsIgnoreCase("/dev/bus/usb/001/004")){
BAUD_RATE = Integer.valueOf(sessionManager.getCOUNTER_BAUDRATE());
System.out.println("getCOUNTER_BAUDRATE=============>"+BAUD_RATE);
}else if(device.getDeviceName().equalsIgnoreCase("/dev/bus/usb/001/003")){
BAUD_RATE = Integer.valueOf(sessionManager.getSCALE_BAUDRATE());
System.out.println("getSCALE_BAUDRATE=============>"+BAUD_RATE);
}
// There is a device connected to our Android device. Try to open it as a Serial Port.
requestUserPermission();
keep = false;
} else {
connection = null;
device = null;
}
}
if (!keep)
break;
}
if (!keep) {
// There is no USB devices connected (but usb host were listed). Send an intent to MainActivity.
Intent intent = new Intent(ACTION_NO_USB);
sendBroadcast(intent);
}
} else {
// There is no USB devices connected. Send an intent to MainActivity
Intent intent = new Intent(ACTION_NO_USB);
sendBroadcast(intent);
}
}
private void setFilter() {
IntentFilter filter = new IntentFilter();
filter.addAction(ACTION_USB_PERMISSION);
filter.addAction(ACTION_USB_DETACHED);
filter.addAction(ACTION_USB_ATTACHED);
registerReceiver(usbReceiver, filter);
}
/*
* Request user permission. The response will be received in the BroadcastReceiver
*/
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1) private void requestUserPermission() {
PendingIntent mPendingIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
usbManager.requestPermission(device, mPendingIntent);
}
public class UsbBinder extends Binder {
public UsbService getService() {
return UsbService.this;
}
}
/*
* A simple thread to open a serial port.
* Although it should be a fast operation. moving usb operations away from UI thread is a good thing.
*/
private class ConnectionThread extends Thread {
@Override
public void run() {
serialPort = UsbSerialDevice.createUsbSerialDevice(device, connection);
if (serialPort != null) {
if (serialPort.open()) {
serialPort.setBaudRate(BAUD_RATE);
serialPort.setDataBits(UsbSerialInterface.DATA_BITS_8);
serialPort.setStopBits(UsbSerialInterface.STOP_BITS_1);
serialPort.setParity(UsbSerialInterface.PARITY_NONE);
serialPort.setFlowControl(UsbSerialInterface.FLOW_CONTROL_OFF);
serialPort.read(mCallback);
// Everything went as expected. Send an intent to MainActivity
Intent intent = new Intent(ACTION_USB_READY);
context.sendBroadcast(intent);
} else {
// Serial port could not be opened, maybe an I/O error or if CDC driver was chosen, it does not really fit
// Send an Intent to Main Activity
if (serialPort instanceof CDCSerialDevice) {
Intent intent = new Intent(ACTION_CDC_DRIVER_NOT_WORKING);
context.sendBroadcast(intent);
} else {
Intent intent = new Intent(ACTION_USB_DEVICE_NOT_WORKING);
context.sendBroadcast(intent);
}
}
} else {
// No driver for given device, even generic CDC driver could not be loaded
Intent intent = new Intent(ACTION_USB_NOT_SUPPORTED);
context.sendBroadcast(intent);
}
}
}
}
有人知道如何实现这一目标。我也愿意使用另一个可以帮助我一次连接多个USB串行设备的库。