未使用 Java 检测串行端口

Question

我正在尝试连接到我的串行端口“COM6”，但现在我无法连接到它。我尝试使用portId.getName() 打印出可用的串行端口列表。它显示了可用的串行端口列表，但 COM6 没有显示在那里。

这是我的 Java 代码：

portList = CommPortIdentifier.getPortIdentifiers();

    while (portList.hasMoreElements()) {
        portId = (CommPortIdentifier) portList.nextElement();
        if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
            if (portId.getName().equals("COM6")) {
            //if (portId.getName().equals("/dev/term/a")) {
                try {
                    serialPort = (SerialPort)
                    portId.open("Arduino", 2000);
                } catch (PortInUseException e) {
                    System.out.println("Error1 is "+ e);
                }
                try {
                    outputStream = serialPort.getOutputStream();
                } catch (IOException e) {
                    System.out.println("Error2 is "+ e);
                }
                try {
                    serialPort.setSerialPortParams(9600,
                        SerialPort.DATABITS_8,
                        SerialPort.STOPBITS_1,
                        SerialPort.PARITY_NONE);
                } catch (UnsupportedCommOperationException e) {
                    System.out.println("Error3 is "+ e);
                }

                try{
                    byte data1 = 1;
                    outputStream.write(data1);
                    System.out.println("helo");
                    System.out.println(data1);

                }catch(IOException e){
                    System.out.println("Error 3: " + e);
                }

            }

        }
    }
    serialPort.close();

我已在设备管理器中检查了 COM6。它显示可用。如果我在 vb 中运行相同的 com 端口，它会完美运行。谁能帮我解决这个问题。谢谢。

Answer 1

我猜你正在尝试与 Arduino 交流？如果是这样，您必须安装Arduino IDE - 还包含 RXTX 库，它与 Java 通信 API 非常相似。 那你可以试试这段代码，和你的很相似：

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
        "COM3", // 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");
}

}

代码来自Arduino Playground，我现在无法试用，但我在两三个月前使用此代码连接了一个 Arduino（Windows 8、64 位）。帖子中还描述了其他方法，以及所有必要的要求（例如类路径变量） - 在您的系统设置中检查它们。

希望对您有所帮助。