端口目前拥有未知的Windows应用程序-条码读取问题

Question

我用java语言编写了读取条形码的程序，使用Device Argox条形码阅读器，型号为As-8250。我使用javax.com jar进行串行通信。下面是我写的从COM13端口号读取的程序。

我还将Argox实用程序的默认端口号设置为COM13。

package scanhandler;

import java.awt.AWTException;
import java.awt.Robot;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.util.Enumeration;
import java.util.Properties;
import java.util.TooManyListenersException;
import javax.comm.CommPortIdentifier;
import javax.comm.PortInUseException;
import javax.comm.SerialPort;
import javax.comm.SerialPortEvent;
import javax.comm.SerialPortEventListener;
import javax.comm.UnsupportedCommOperationException;
public class ScanHandler implements Runnable, SerialPortEventListener {
    private static CommPortIdentifier   myCommPortIdentifier;
    private static Enumeration          portList;
    private static String               TimeStamp;
    private static String               driverClass;
    private static String               connectionString;
    private static String               comPort;    
    private Connection                  myConnection;
    private InputStream                 myInputStream;
    private Robot                       myRobot;
    private SerialPort                  mySerialPort;
    private Thread                      myThread;

    public ScanHandler() {
        // open serial port
        try {
            TimeStamp = new java.util.Date().toString();
            mySerialPort = (SerialPort) myCommPortIdentifier.open("ComControl", 2000);
            //System.out.println(TimeStamp + ": " + myCommPortIdentifier.getName() + " opened for scanner input");
        } catch (PortInUseException e) {
            e.printStackTrace();
        }
        // get serial input stream
        try {
            myInputStream = mySerialPort.getInputStream();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // add an event listener on the port
        try {
            mySerialPort.addEventListener(this);
        } catch (TooManyListenersException e) {
            e.printStackTrace();
        }
        mySerialPort.notifyOnDataAvailable(true);
        // set up the serial port properties
        try {
            mySerialPort.setSerialPortParams(9600,
                SerialPort.DATABITS_8,
                SerialPort.STOPBITS_1,
                SerialPort.PARITY_NONE);
            mySerialPort.setDTR(false);
            mySerialPort.setRTS(false);
        } catch (UnsupportedCommOperationException e) {
            e.printStackTrace();
        }
        // make a robot to pass keyboard data
        try {
            myRobot = new Robot();
        } catch (AWTException e) {
            e.printStackTrace();
        }
        // create the thread
        myThread = new Thread(this);
        myThread.start();
    }
    public void run() {
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {}
    }
    // on scan
    public void serialEvent(SerialPortEvent event) {
        if (event.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
            StringBuilder myStringBuilder = new StringBuilder();
            int c;
            try {
                // append the scanned data onto a string builder
                while ((c = myInputStream.read()) != 10){
                   if (c != 13)  myStringBuilder.append((char) c);
                }               
                // send to keyboard buffer if it the barcode doesn't start with '5'
                if (myStringBuilder.charAt(0) != '5') {
                    for (int i = 0; i < myStringBuilder.length(); i++) {
                        myRobot.keyPress((int) myStringBuilder.charAt(i));
                        myRobot.keyRelease((int) myStringBuilder.charAt(i));
                    }
                // here's the scanned barcode as a variable!
                } else {
                    TimeStamp = new java.util.Date().toString();
                    System.out.println(TimeStamp + ": scanned input received:" + myStringBuilder.toString());                    
                }
                // close the input stream
                myInputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    public static void main(String[] args) {
        // read ScanHandler properties
        Properties myProperties = new Properties();
        // myProperties.load(new FileInputStream("config.properties"));
        comPort             = "COM13";              
        try {
            // get our pre-defined COM port
            myCommPortIdentifier = CommPortIdentifier.getPortIdentifier(comPort);
            ScanHandler reader = new ScanHandler();
        } catch (Exception e) {
            TimeStamp = new java.util.Date().toString();
            System.out.println(TimeStamp + ": " + comPort + " " + myCommPortIdentifier);
            System.out.println(TimeStamp + ": msg1 - " + e);
        }
    };    
}

->这个程序正在监听端口COM13，并打印输入流中的字符串(由条形码阅读器扫描)。

->========================== 问题是这里 =======================当我首先插入Usb并通过设备实用程序强制使用端口COM13时。它工作得很完美。之后，当我运行我的Java程序监听同一端口它抛出异常

javax.comm.PortInUseException: Port currently owned by Unknown Windows Application
    at javax.comm.CommPortIdentifier.open(CommPortIdentifier.java:337)
    at scanhandler.ScanHandler.<init>(ScanHandler.java:41)
    at scanhandler.ScanHandler.main(ScanHandler.java:141)
Fri Jun 13 12:20:05 IST 2014: COM13 javax.comm.CommPortIdentifier@d1a2f1
Fri Jun 13 12:20:05 IST 2014: msg1 - java.lang.NullPointerException

那么，如果我的程序在该端口上被拒绝侦听，我怎么能读取扫描的条形码呢?

Answer 1

下面将显示当前使用特定端口的应用程序的PID:

C:Usersuser>netstat -ano | findstr ":5984"

输出看起来像这样:

  TCP    127.0.0.1:5984         0.0.0.0:0              LISTENING       2036
  TCP    127.0.0.1:5984         127.0.0.1:55706        ESTABLISHED     2036
  TCP    127.0.0.1:5984         127.0.0.1:55710        ESTABLISHED     2036
  TCP    127.0.0.1:5984         127.0.0.1:55711        ESTABLISHED     2036
  TCP    127.0.0.1:5984         127.0.0.1:55712        ESTABLISHED     2036
  TCP    127.0.0.1:5984         127.0.0.1:55713        ESTABLISHED     2036
  TCP    127.0.0.1:5984         127.0.0.1:55714        ESTABLISHED     2036
  TCP    127.0.0.1:55706        127.0.0.1:5984         ESTABLISHED     4716
  TCP    127.0.0.1:55710        127.0.0.1:5984         ESTABLISHED     4716
  TCP    127.0.0.1:55711        127.0.0.1:5984         ESTABLISHED     4716
  TCP    127.0.0.1:55712        127.0.0.1:5984         ESTABLISHED     4716
  TCP    127.0.0.1:55713        127.0.0.1:5984         ESTABLISHED     4716
  TCP    127.0.0.1:55714        127.0.0.1:5984         ESTABLISHED     4716

您可以使用tasklist命令或任务管理器查找名称:

C:Usersuser>tasklist | findstr "2036"
erl.exe                       2036 Services                   0     15,604 K