使用java RXTXcomm.jar的Commport连接到COM1的InputStream无法读取

Question

我有一个简单的类，使用RXTXcomm.jar类读取和写入数据到COM1。在我打开连接并写一个新行后，没有什么可读的。 inputStream的available（）始终返回0.

    public class ComPortUtility() {
    CommPort commPort;
    SerialPort serialPort;
    InputStream in;
    OuputStream out;
    int timeout = 10000;

    public boolean connect()
    {
     try {
        CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier("COM1");
     if ( portIdentifier.isCurrentlyOwned() )
        {
            System.out.println("Error: Port is currently in use");
            return false;
        }
        else
        {
            this.commPort = portIdentifier.open(this.getClass().getName(),this.timeout);

            if ( commPort instanceof SerialPort )
            {
                this.serialPort = (SerialPort) commPort;
                //setting baud rate, data bits, stop bit, parity
                serialPort.setSerialPortParams(19200,SerialPort.DATABITS_8,SerialPort.STOPBITS_1,SerialPort.PARITY_NONE);
                //setting flow control
                serialPort.setFlowControlMode(SerialPort.FLOWCONTROL_NONE);
                System.out.println("BaudRate: " + serialPort.getBaudRate());
                System.out.println("DataBits: " + serialPort.getDataBits());
                System.out.println("StopBits: " + serialPort.getStopBits());
                System.out.println("Parity: " + serialPort.getParity());
                System.out.println("FlowControl: " + serialPort.getFlowControlMode());
                this.in = serialPort.getInputStream();
                this.out = serialPort.getOutputStream();
                write("\n");
                int b = -1;
                while((b=this.in.read())!=-1) {
                    System.out.println("data: "+b);
                }
           }
       }
    } catch (Exception e) {
        System.out.println("Exception: "+e.getMessage());
        return false;
    } 

    private void write(String command) {
    try {
        this.out.write(command.getBytes());
        this.out.flush();
    } catch (Exception e) {
        e.printStackTrace();
    }
  }
}

什么都没打印出来。任何想法都赞赏！