我晕啦,终于成功了,原来是我的基础不稳固造成的,呵呵今天成功了!!!

import java.util.*;

import java.io.*;

import javax.comm.*;

public class Jcomm

{

     static OutputStream out;

     static InputStream  in;

     public static void main(String args[]) throws IOException

     {

         BufferedReader buf=new BufferedReader(new InputStreamReader(System.in));

         Enumeration ports = CommPortIdentifier.getPortIdentifiers();

         String portName;

         CommPortIdentifier portId;

         SerialPort serialPort;

         if (ports == null)

         {

   System.out.println("No comm ports found!");

         }

         else

            while(ports.hasMoreElements())

            {

    System.out.println(" "+ ((CommPortIdentifier) ports.nextElement()).getName());

                System.out.print("Selet one port from the list up:");

                portName=buf.readLine();

                try

                {

                   portId=CommPortIdentifier.getPortIdentifier(portName);

                   try

                   {

                       serialPort=(SerialPort)portId.open("Jcomm",2000);

                     try

                     {

                        serialPort.setSerialPortParams(9600,SerialPort.DATABITS_8,SerialPort.STOPBITS_1,SerialPort.PARITY_NONE);

                        System.out.println("Port Open Successfully!");

                        serialPort.close();

                     }

                     catch(UnsupportedCommOperationException e)

                     {

                        System.out.println("Port set failed!"); 

                     }

                   }

                   catch(PortInUseException e){}

                 }

                 catch(NoSuchPortException e){}

             }

     }

} 

把上面的try欢欢位置就ok了!