的java没有看到连接的设备COM4

Question

Java是没有看到在COM4的arudino的代码似乎是工作

package tester; 
import java.io.BufferedReader; 
import java.io.InputStreamReader; 
import java.io.OutputStream; 
import gnu.io.CommPortIdentifier; 
import gnu.io.SerialPort; 
import gnu.io.SerialPortEvent; 
import gnu.io.SerialPortEventListener; 
import java.util.Enumeration; 
public class SerialTest implements SerialPortEventListener { 
SerialPort serialPort; 
    /** The port we're normally going to use. */ 
private static final String PORT_NAMES[] = { 
     "/dev/tty.usbserial-A9007UX1", // Mac OS X 
        "/dev/ttyACM0", // Raspberry Pi 
     "/dev/ttyUSB0", // Linux 
     "COM4", // Windows 
}; 
/** 
* A BufferedReader which will be fed by a InputStreamReader 
* converting the bytes into characters 
* making the displayed results codepage independent 
*/ 
private BufferedReader input; 
/** The output stream to the port */ 
private OutputStream output; 
/** Milliseconds to block while waiting for port open */ 
private static final int TIME_OUT = 2000; 
/** Default bits per second for COM port. */ 
private static final int DATA_RATE = 9600; 

public void initialize() { 
      // the next line is for Raspberry Pi and 
      // gets us into the while loop and was suggested here was  suggested http://www.raspberrypi.org/phpBB3/viewtopic.php?f=81&t=32186 
      System.setProperty("gnu.io.rxtx.SerialPorts", "/dev/ttyACM0"); 

    CommPortIdentifier portId = null; 
    Enumeration portEnum = CommPortIdentifier.getPortIdentifiers(); 

    //First, Find an instance of serial port as set in PORT_NAMES. 
    while (portEnum.hasMoreElements()) { 
     CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement(); 
     for (String portName : PORT_NAMES) { 
      if (currPortId.getName().equals(portName)) { 
       portId = currPortId; 
       break; 
      } 
     } 
    } 
    if (portId == null) { 
     System.out.println("Could not find COM port."); 
     return; 
    } 

    try { 
     // open serial port, and use class name for the appName. 
     serialPort = (SerialPort) portId.open(this.getClass().getName(), 
       TIME_OUT); 

     // set port parameters 
     serialPort.setSerialPortParams(DATA_RATE, 
       SerialPort.DATABITS_8, 
       SerialPort.STOPBITS_1, 
       SerialPort.PARITY_NONE); 

     // open the streams 
     input = new BufferedReader(new InputStreamReader(serialPort.getInputStream())); 
     output = serialPort.getOutputStream(); 

     // add event listeners 
     serialPort.addEventListener(this); 
     serialPort.notifyOnDataAvailable(true); 
    } catch (Exception e) { 
     System.err.println(e.toString()); 
    } 
} 

/** 
* This should be called when you stop using the port. 
* This will prevent port locking on platforms like Linux. 
*/ 
public synchronized void close() { 
    if (serialPort != null) { 
     serialPort.removeEventListener(); 
     serialPort.close(); 
    } 
} 

/** 
* Handle an event on the serial port. Read the data and print it. 
*/ 
public synchronized void serialEvent(SerialPortEvent oEvent) { 
    if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) { 
     try { 
      String inputLine=input.readLine(); 
      System.out.println(inputLine); 
     } catch (Exception e) { 
      System.err.println(e.toString()); 
     } 
    } 
    // Ignore all the other eventTypes, but you should consider the other ones. 
} 

public static void main(String[] args) throws Exception { 
    SerialTest main = new SerialTest(); 
    main.initialize(); 
    Thread t=new Thread() { 
     public void run() { 
      //the following line will keep this app alive for 1000 seconds, 
      //waiting for events to occur and responding to them (printing incoming messages to console). 
      try {Thread.sleep(1000000);} catch (InterruptedException ie) {} 
     } 
    }; 
    t.start(); 
    System.out.println("Started"); 
}} 

似乎是工作，但所有我在控制台得到的是

WARNING: RXTX Version mismatch 
Jar version = RXTX-2.2pre1 
native lib Version = RXTX-2.2pre2 
Could not find COM port. 
Started 

我看着在罐子版本关闭，但rxtx要求它在那里稳定版本

Answer 1

为什么你认为它将永远是“COM4”在Windows上？也许试图得到像这样的COM端口（从http://www.programcreek.com/java-api-examples/index.php?api=gnu.io.CommPortIdentifier）：

public static List<String> getSerialPorts(){ 
    List<String> vp=new ArrayList<String>(); 
    Enumeration portList=CommPortIdentifier.getPortIdentifiers(); 
    while (portList.hasMoreElements()) { 
    CommPortIdentifier portId=(CommPortIdentifier)portList.nextElement(); 
    if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) { 
     vp.add(portId.getName()); 
    } 
    } 
    return vp; 
}