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目前我正尝试通过Java与并行端口进行通信，但事实证明这很麻烦。我目前正在使用EEG进行大脑研究，我想发送简单的“事件标记”到脑电图系统，这必须通过并行端口进行。我已经使用了javax.comm和RXTX，但由于某些原因，我无法将输出写入端口。测试码如下：并行端口通信Rxtx或javax.comm
import gnu.io.*; // RXTX
// import javax.comm.*; // javax.comm
public class PrlCom {
private String msg= "1";
private OutputStream outputStream;
private InputStream inputStream;
private ParallelPort parallelPort; // can be both Rxtx or javax.comm
private CommPortIdentifier port;
// CONSTANTS
public final String PARALLEL_PORT = "LPT1";
public final String[] PORT_TYPE = { "Serial Port", "Parallel Port" };
public static void main(String[] args) {
new PrlCom();
}
public PrlCom(){
openParPort();
}
public void openParPort() {
try {
// get the parallel port connected to the EEG-system (used to be printer)
port = CommPortIdentifier.getPortIdentifier(PARALLEL_PORT);
System.out.println("\nport.portType = " + port.getPortType());
System.out.println("port type = " + PORT_TYPE[port.getPortType() - 1]);
System.out.println("port.name = " + port.getName());
// open the parallel port -- open(App name, timeout)
parallelPort = (ParallelPort) port.open("CommTest", 50);
outputStream = parallelPort.getOutputStream();
inputStream = parallelPort.getInputStream();
System.out.println("Write...");
outputStream.write(toBytes(msg.toCharArray()));
System.out.println("Flush...");
outputStream.flush();
} catch (NoSuchPortException nspe) {
System.out.println("\nPrinter Port LPT1 not found : " + "NoSuchPortException.\nException:\n" + nspe + "\n");
} catch (PortInUseException piue) {
System.out.println("\nPrinter Port LPT1 is in use : " + "PortInUseException.\nException:\n" + piue + "\n");
} catch (IOException ioe) {
System.out.println("\nPrinter Port LPT1 failed to write : " + "IOException.\nException:\n" + ioe + "\n");
} catch (Exception e) {
System.out.println("\nFailed to open Printer Port LPT1 with exeception : " + e + "\n");
} finally {
if (port != null && port.isCurrentlyOwned()) {
parallelPort.close();
}
System.out.println("Closed all resources.\n");
}
}
我得到的toBytes（）函数从Converting char[] to byte[]。我也直接尝试spam.getBytes（），这没有什么区别。
使用javax.comm包运行此代码后，并行端口无法识别。如果我用RXTX（gnu.io）运行代码，我会得到一个IOException。整个打印输出如下
Stable Library
=========================================
Native lib Version = RXTX-2.1-7
Java lib Version = RXTX-2.1-7
port.portType = 2
port type = Parallel Port
port.name = LPT1
Output stream opened
Write...
Printer Port LPT1 failed to write : IOException.
Exception:
java.io.IOException: The device is not connected.
in writeByte
Closed all resources.
使用Rxtx，代码可以与并行端口建立连接。但是，它无法将一个字节写入输出流。有人可以告诉我如何解决这个问题吗？
我已经阅读了许多其他主题并行端口是多么过时，我应该使用USB。但是，我正在使用EEG系统（BioSemi ActiveTwo和ActiView软件）来测量大脑活动，可悲的是，我没有可能改变这一点。并行端口-USB转换器也无法选择。 （奇怪的是，如此技术先进的东西使用这种过时的硬件）。
非常感谢！