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!