【发布时间】：2012-09-24 07:08:51
【问题描述】：
我必须（写入）将数据“0x01”输出到并行端口。我正在使用以下代码写入端口但它没有写入，程序只是运行并且没有任何反应。
import java.io.*;
import javax.comm.CommPortIdentifier;
import javax.comm.NoSuchPortException;
import javax.comm.ParallelPort;
import javax.comm.PortInUseException;
public class ParallelIO {
private static OutputStream outputStream;
private static InputStream inputStream;
private static ParallelPort parallelPort;
private static CommPortIdentifier port;
static byte dat = 0x02;
public static final String PARALLEL_PORT = "LPT1";
public ParallelIO() {
try {
//detec the port
System.out.println("Port : " + PARALLEL_PORT + " is detected");
// get the parallel port connected to the output
port = CommPortIdentifier.getPortIdentifier(PARALLEL_PORT);
//port identified
System.out.println("Port identified : " + port);
// open the parallel port --
//port(App name, timeout);
parallelPort = (ParallelPort) port.open("0x0378", 50);
//port opened
System.out.println("Port opened : " + parallelPort);
outputStream = parallelPort.getOutputStream();
//get output
System.out.println("Out put taken : " + outputStream);
outputStream.write(dat);
//data written
System.out.println("Data Written : " + dat);
outputStream.flush();
outputStream.close();
} 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 exception : " + e + "\n");
} finally {
if (port != null && port.isCurrentlyOwned()) {
parallelPort.close();
}
System.out.println("Closed all resources.\n");
}
}
public static void main(String[] args) {
ParallelIO parr = new ParallelIO();
}
}
【问题讨论】：
-
什么都没有发生？甚至你的第一个
System.out.println("Port : " + PARALLEL_PORT + " is detected");都没有运行？ -
你必须先设置java通信库的路径
标签： java windows-7 parallel-port