【发布时间】：2015-05-28 13:19:16
【问题描述】：
我正在使用以下代码通过连接到我的三星打印机的 USB 电缆通过 android 设备进行打印。
当使用startPrinting 方法时，它会在调试日志中给我以下验证：
- 成功发送到打印机的命令
- 已授予打印机权限。
打印机甚至开始发出哔哔声，但我提供的数据没有被打印出来。我被困在这个阶段，也没有从谷歌或 stackoverflow 上找到任何帮助。
注意：没有崩溃也没有错误
我正在 Android Jelly bean 4.3 OS 上测试此代码
任何帮助将不胜感激。
private UsbManager mUsbManager;
private UsbDevice mDevice;
private UsbDeviceConnection mConnection;
private UsbInterface mInterface;
private UsbEndpoint mEndPoint;
private PendingIntent mPermissionIntent;
private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
private static Boolean forceCLaim = true;
HashMap<String, UsbDevice> mDeviceList;
Iterator<UsbDevice> mDeviceIterator;
int protocol;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
mDeviceList = mUsbManager.getDeviceList();
mDeviceIterator = mDeviceList.values().iterator();
Button print = (Button) findViewById(R.id.buttonPrint);
Toast.makeText(this, "Device List Size: " + String.valueOf(mDeviceList.size()), Toast.LENGTH_SHORT).show();
TextView textView = (TextView) findViewById(R.id.usbDevice);
String usbDevice = "";
// This is just testing what devices are connected
while (mDeviceIterator.hasNext())
{
UsbDevice usbDevice1 = mDeviceIterator.next();
usbDevice += "\n" + "DeviceID: " + usbDevice1.getDeviceId() + "\n" + "DeviceName: " + usbDevice1.getDeviceName() + "\n" + "DeviceClass: " + usbDevice1.getDeviceClass() + " - "
+ translateDeviceClass(usbDevice1.getDeviceClass()) + "\n" + "DeviceSubClass: " + usbDevice1.getDeviceSubclass() + "\n" + "VendorID: " + usbDevice1.getVendorId() + "\n" + "ProductID: " + usbDevice1.getProductId()
+ "\n";
protocol = usbDevice1.getDeviceProtocol();
int interfaceCount = usbDevice1.getInterfaceCount();
Toast.makeText(this, "INTERFACE COUNT: " + String.valueOf(interfaceCount), Toast.LENGTH_SHORT).show();
mDevice = usbDevice1;
if (mDevice == null)
{
Toast.makeText(this, "mDevice is null", Toast.LENGTH_SHORT).show();
}
else
{
// Toast.makeText(this, "mDevice is not null", Toast.LENGTH_SHORT).show();
}
textView.setText(usbDevice);
}
if (mDevice == null)
{
Toast.makeText(this, "mDevice is null", Toast.LENGTH_SHORT).show();
}
else
{
// Toast.makeText(this, "mDevice is not null", Toast.LENGTH_SHORT).show();
}
print.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View view)
{
mPermissionIntent = PendingIntent.getBroadcast(MainActivity.this, 0, new Intent(ACTION_USB_PERMISSION), 0);
IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
registerReceiver(mUsbReceiver, filter);
if (mDevice != null)
mUsbManager.requestPermission(mDevice, mPermissionIntent);
// else
// Toast.makeText(this, "USB ", Toast.LENGTH_SHORT).show();
// print(mConnection, mInterface);
}
});
}
private String translateDeviceClass(int deviceClass)
{
switch (deviceClass)
{
case UsbConstants.USB_CLASS_APP_SPEC:
return "Application specific USB class";
case UsbConstants.USB_CLASS_AUDIO:
return "USB class for audio devices";
case UsbConstants.USB_CLASS_CDC_DATA:
return "USB class for CDC devices (communications device class)";
case UsbConstants.USB_CLASS_COMM:
return "USB class for communication devices";
case UsbConstants.USB_CLASS_CONTENT_SEC:
return "USB class for content security devices";
case UsbConstants.USB_CLASS_CSCID:
return "USB class for content smart card devices";
case UsbConstants.USB_CLASS_HID:
return "USB class for human interface devices (for example, mice and keyboards)";
case UsbConstants.USB_CLASS_HUB:
return "USB class for USB hubs";
case UsbConstants.USB_CLASS_MASS_STORAGE:
return "USB class for mass storage devices";
case UsbConstants.USB_CLASS_MISC:
return "USB class for wireless miscellaneous devices";
case UsbConstants.USB_CLASS_PER_INTERFACE:
return "USB class indicating that the class is determined on a per-interface basis";
case UsbConstants.USB_CLASS_PHYSICA:
return "USB class for physical devices";
case UsbConstants.USB_CLASS_PRINTER:
return "USB class for printers";
case UsbConstants.USB_CLASS_STILL_IMAGE:
return "USB class for still image devices (digital cameras)";
case UsbConstants.USB_CLASS_VENDOR_SPEC:
return "Vendor specific USB class";
case UsbConstants.USB_CLASS_VIDEO:
return "USB class for video devices";
case UsbConstants.USB_CLASS_WIRELESS_CONTROLLER:
return "USB class for wireless controller devices";
default:
return "Unknown USB class!";
}
}
// Broadcast receiver to obtain permission from user for connection
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)
{
UsbDevice device = (UsbDevice) intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false))
{
if (device != null)
{
// call method to set up device communication
mInterface = device.getInterface(0);
mEndPoint = mInterface.getEndpoint(0);
mConnection = mUsbManager.openDevice(device);
Log.i("Info", "Device permission granted");
startPrinting(device);
// setup();
}
}
else
{
// Log.d("SUB", "permission denied for device " + device);
Toast.makeText(context, "PERMISSION DENIED FOR THIS DEVICE", Toast.LENGTH_SHORT).show();
}
}
}
}
};
public void startPrinting(final UsbDevice printerDevice)
{
Handler handler = new Handler();
handler.post(new Runnable()
{
UsbDeviceConnection conn;
UsbInterface usbInterface;
@Override
public void run()
{
try
{
Log.i("Info", "Bulk transfer started");
// usbInterface = printerDevice.getInterface(0);
for (int i = 0; i < printerDevice.getInterfaceCount(); i++)
{
usbInterface = printerDevice.getInterface(i);
if (usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_PRINTER)
{
// usbInterface = mDevice;
}
}
UsbEndpoint endPoint = usbInterface.getEndpoint(0);
conn = mUsbManager.openDevice(mDevice);
conn.claimInterface(usbInterface, true);
String myStringData = "TEXT";
myStringData += "\n";
byte[] array = myStringData.getBytes();
ByteBuffer output_buffer = ByteBuffer.allocate(array.length);
UsbRequest request = new UsbRequest();
request.initialize(conn, endPoint);
request.queue(output_buffer, array.length);
if (conn.requestWait() == request)
{
Log.i("Info", output_buffer.getChar(0) + "");
Message m = new Message();
m.obj = output_buffer.array();
output_buffer.clear();
}
else
{
Log.i("Info", "No request recieved");
}
int transfered = conn.bulkTransfer(endPoint, myStringData.getBytes(), myStringData.getBytes().length, 5000);
Log.i("Info", "Amount of data transferred : " + transfered);
}
catch (Exception e)
{
Log.e("Exception", "Unable to transfer bulk data");
e.printStackTrace();
}
finally
{
try
{
conn.releaseInterface(usbInterface);
Log.i("Info", "Interface released");
conn.close();
Log.i("Info", "Usb connection closed");
unregisterReceiver(mUsbReceiver);
Log.i("Info", "Brodcast reciever unregistered");
}
catch (Exception e)
{
Log.e("Exception", "Unable to release resources because : " + e.getMessage());
e.printStackTrace();
}
}
}
});
}
private void print(UsbDeviceConnection connection, UsbInterface intrface)
{
String test = "THIS IS A PRINT TEST";
// String text = "#move " + protocol + ";" + "#print" + test;
// Log.e("text", text);
byte[] testBytes = test.getBytes();
if (intrface == null)
{
Toast.makeText(this, "INTERFACE IS NULL", Toast.LENGTH_SHORT).show();
}
if (connection == null)
{
Toast.makeText(this, "CONNECTION IS NULL", Toast.LENGTH_SHORT).show();
}
if (forceCLaim == null)
{
Toast.makeText(this, "FORCE CLAIM IS NULL", Toast.LENGTH_SHORT).show();
}
connection.claimInterface(intrface, forceCLaim);
connection.bulkTransfer(mEndPoint, testBytes, testBytes.length, 0);
connection.close();
}
【问题讨论】：
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我想你可能需要为这个问题开始赏金......