Ubuntu RXTX不识别USB
我将一个带有librxtx-java的设备连接到Ubuntu。 该代码以前工作在10.04，但在12.04，它无法发现连接到计算机的USB串行。
java.util.Enumeration<CommPortIdentifier> portEnum = CommPortIdentifier.getPortIdentifiers();
while ( portEnum.hasMoreElements() )
{
CommPortIdentifier portIdentifier = portEnum.nextElement();
System.out.println( portIdentifier.getName() + " - " + getPortTypeName(portIdentifier.getPortType()) );
}
尽管安装了适当的librxtx-java库并且识别了设备（dmesg | tail在一行中显示USB“串行设备转换器检测到”），但代码的这一部分从未进入while循环。
更新：
它看起来像Ubuntu 12.04 64位不适用于任何USB串行设备（尽管它们显示在dmesg中并显示为/ dev / ttyUSB，但它似乎不仅仅是Java的问题。
我安装了Ubuntu 11.10内核3.0.0-12-generic-pae和librxtx-java version 2.2pre2-8 。 使用下面的代码，它会正确列出我的串行端口。 现在你有USB串口转换器安装正确？ 您需要检查转换器使用的端口。 使用下面的示例应用程序，您可以尝试类似java -cp /usr/share/java/RXTXcomm.jar:. GetCommPorts 2 java -cp /usr/share/java/RXTXcomm.jar:. GetCommPorts 2
请确保您在/ dev /中的ttySXX或ttyUSBXX文件中拥有正确的权限。
crw-rw---- 1 root dialout 4, 65 2012-02-29 01:08 /dev/ttyS1
crw-rw---- 1 root dialout 4, 66 2012-02-29 01:08 /dev/ttyS2
这些串行端口显示在我的系统中，想要运行该应用程序的用户应该在组拨出。 要添加自己，请使用：
sudo usermod -a -G dialout username
你现在应该在“拨出”组。
import gnu.io.CommPortIdentifier;
import gnu.io.NoSuchPortException;
import gnu.io.PortInUseException;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import gnu.io.UnsupportedCommOperationException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Enumeration;
import java.util.TooManyListenersException;
public class GetCommPorts
{
static Enumeration<CommPortIdentifier> portList;
static CommPortIdentifier portId;
static SerialPort serialPort;
static OutputStream outputStream;
static boolean outputBufferEmptyFlag = false;
public static class SerialReader implements SerialPortEventListener
{
private InputStream in;
private byte[] buffer = new byte[1024];
public SerialReader(InputStream in)
{
this.in = in;
}
@Override
/**
* treat n as end of block.
*/
public void serialEvent(SerialPortEvent ev)
{
int data;
try
{
int len = 0;
while ( (data = in.read()) > -1)
{
if (data == 'n')
{
break;
}
buffer[len++] = (byte) data;
}
System.out.println(new String(buffer, 0, len));
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
System.exit(-1);
}
}
}
public static class SerialWriter implements Runnable
{
OutputStream out;
public SerialWriter(OutputStream out)
{
this.out = out;
}
@Override
public void run()
{
try
{
int c = 0;
while ( (c = System.in.read()) > -1)
{
this.out.write(c);
}
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
System.exit(-1);
}
}
}
private static String getPortTypeName ( int portType )
{
switch ( portType )
{
case CommPortIdentifier.PORT_I2C:
return "I2C";
case CommPortIdentifier.PORT_PARALLEL:
return "Parallel";
case CommPortIdentifier.PORT_RAW:
return "Raw";
case CommPortIdentifier.PORT_RS485:
return "RS485";
case CommPortIdentifier.PORT_SERIAL:
return "Serial";
default:
return "unknown type";
}
}
private static void listPorts()
{
@SuppressWarnings("unchecked")
java.util.Enumeration<CommPortIdentifier> portEnum = CommPortIdentifier.getPortIdentifiers();
while ( portEnum.hasMoreElements() )
{
CommPortIdentifier portIdentifier = portEnum.nextElement();
System.out.println(portIdentifier.getName() + " - " + getPortTypeName(portIdentifier.getPortType()) );
if (portIdentifier.getPortType() == 1)
{
try
{
serialPort = (SerialPort) portIdentifier.open(portIdentifier.getName(), 3000);
}
catch (PortInUseException e)
{
System.err.print("port in use");
continue;
}
System.out.println("Baud is " + serialPort.getBaudRate());
System.out.println("Bits is " + serialPort.getDataBits());
System.out.println("Stop is " + serialPort.getStopBits());
System.out.println("Par is " + serialPort.getParity());
serialPort.close();
}
}
}
private static int doReadWrite(String portName)
{
CommPortIdentifier portIdentifier;
try
{
portIdentifier = CommPortIdentifier.getPortIdentifier(portName);
if (portIdentifier.isCurrentlyOwned())
{
System.err.println("error: port is currently in use");
return -1;
}
SerialPort sport = (SerialPort) portIdentifier.open(portName, 3000);
sport.setSerialPortParams(57600, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
InputStream in = sport.getInputStream();
OutputStream out = sport.getOutputStream();
(new Thread(new SerialWriter(out))).start();
sport.addEventListener(new SerialReader(in));
sport.notifyOnDataAvailable(true);
}
catch (NoSuchPortException e)
{
e.printStackTrace();
return -1;
}
catch (PortInUseException e)
{
e.printStackTrace();
return -1;
}
catch (UnsupportedCommOperationException e)
{
e.printStackTrace();
return -1;
}
catch (IOException e)
{
e.printStackTrace();
return -1;
}
catch (TooManyListenersException e)
{
e.printStackTrace();
return -1;
}
return 0;
}
static void showHelp()
{
System.out.println("Usage " + GetCommPorts.class.getName() + "N");
System.out.println("1 read and write from the serial port");
System.out.println("2 list all serial ports in the system");
System.out.println("default show this help ");
}
public static void main(String[] args)
{
int operation = 0;
try
{
if (args.length != 1)
{
showHelp();
return;
}
operation = Integer.parseInt(args[0]);
}
catch (NumberFormatException e)
{
}
switch (operation)
{
case 1:
doReadWrite("/dev/ttyUSB0");
break;
case 2:
listPorts();
break;
default:
showHelp();
}
}
}
这个应用程序的输出：
$ java -cp /usr/share/java/RXTXcomm.jar:. GetCommPorts 2
/dev/ttyS1 - Serial
Baud is 9600
Bits is 8
Stop is 1
Par is 0
/dev/ttyS0 - Serial
Baud is 9600
Bits is 8
Stop is 1
Par is 0