Why am I getting a Java NoSuchPortException when the port exists?

问题

Got the following production code below, I'm using it for a new driver. portName is COM4 and this port exists on the PC (and I can connect to it with hyperterminal), so why does Javacomm throw a NoSuchPortException? COM4 shows up fine in device mgr. too

    final String portName = getSerialPort();
    try {
        final CommPortIdentifier id = CommPortIdentifier.getPortIdentifier(portName);
        port = (SerialPort) id.open(getName(), 1000);
    } catch (NoSuchPortException nspe) {
        report(SeverityCode.LEVEL2, getName(), "PIN Pad is not connected to " + portName + " port, or the port does not exist.");
        return;
    } catch (PortInUseException piue) {
        report(SeverityCode.LEVEL2, getName(), portName + " port is already in-use by some other device. Reason: " + piue.getMessage());
        return;
    }

回答1:

Try enumerating the list of ports that are available on your system using the CommPortIdentifier.getPortIdentifiers() and print what's listed. Are you sure that you installed the jarfiles and dll in the correct folders? If yes, then try adding COM4 using CommPortIdentifier.addPortName(java.lang.String portName, int portType, CommDriver driver) .You can set the driver parameter to null to use the default driver.

来源：https://stackoverflow.com/questions/3026804/why-am-i-getting-a-java-nosuchportexception-when-the-port-exists