Automatically detect which Com Port is connected to a USB GSM Modem using Java

Question

I wrote a Java application that reads and sends SMS messages from a USB GSM modem. I'm using SMSLib (which uses JavaCommAPI), and it runs on Windows. I need to pass in the COM PORT, that the modem appears to be connected to.

So far, I've been looking up the COM PORT manually using the Windows Device Manager, and write it into a properties file. I'm wondering if there's a way to detect which COM PORT, the modem is connected to programmatically?

1. It'll save the trouble of looking it up every time
2. The port number changes if I unplug/replug it sometimes

Thanks!!

Answer 1

package com.cubepro.util;

import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Formatter;

import org.apache.log4j.Logger;
import org.smslib.helper.CommPortIdentifier;

import com.cubepro.general.CommonConstants;

import com.cubepro.util.SendMessage;

public class CommPortTester {
   private static final String _NO_DEVICE_FOUND = "  no device found";

   private final static Formatter _formatter = new Formatter(System.out);

   private static Logger log = Logger.getLogger(CommPortTester.class);

   static CommPortIdentifier portId;

   static Enumeration<CommPortIdentifier> portList;

   static int bauds[] = { 9600, 14400, 19200, 28800, 33600, 38400, 56000,
                          57600, 115200 };

   public static final String MAINCLASS = "org.smslib.Service";

   public CommPortTester() throws Exception {
      Class.forName(MAINCLASS);
   }

   /**
    * Wrapper around {@link CommPortIdentifier#getPortIdentifiers()} to be
    * avoid unchecked warnings.
    */
   private static Enumeration<CommPortIdentifier> getCleanPortIdentifiers() {
      return CommPortIdentifier.getPortIdentifiers();
   }

   public String testAndQualifyPort() throws Exception {
      String status = CommonConstants.MODEM_STATUS_ERROR;
      SendMessage sendMessage = new SendMessage();

      log.debug("\nSearching for devices...");
      portList = getCleanPortIdentifiers();

      while (portList.hasMoreElements()) {
         portId = portList.nextElement();
         if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
            _formatter.format("%nFound port: %-5s%n", portId.getName());
            try {
               if(portId.getName()
               boolean comPortSuccess = sendMessage.doIt(portId.getName());
               if(comPortSuccess == true){
                  return portId.getName();
               }
            } catch (final Exception e) {
               log.debug(" Modem error occured -",e);
            }
         }
      }
      log.debug("\nTest complete.");
      return status;
   }

   public static void main(String[]args){
      try{
      CommPortTester tester = new CommPortTester(); 
      tester.testAndQualifyPort();
      }catch(Exception e){
         e.printStackTrace();
      }
   }
}