从输入流串行端口Java读取时出现异常（java.io.IOException：底层输入流返回零字节）

Question

我正在尝试从串行端口读取输入流但是获得异常＆＃34; java.io.IOException：底层输入流返回零字节＆＃34;

以下是代码：

package communication;

import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.charset.StandardCharsets;
import java.util.Enumeration;
import org.apache.commons.io.IOUtils;

public class Serial_0306 implements SerialPortEventListener {

    public SerialPort serialPort;

    private static final String PORT_NAMES[] = {   
        "COM3", // Windows
    };
enter code herepublic static BufferedReader input;
    public static OutputStream output;
    public static InputStream inputStream;

    public static final int TIME_OUT = 2000;   
    public static final int DATA_RATE = 9600;

    public void initialize() {
        CommPortIdentifier portId = null;
        Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();

        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 {
            serialPort = (SerialPort) portId.open(this.getClass().getName(),
                    TIME_OUT);

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

            inputStream = serialPort.getInputStream();
            String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8); // Exception over here
            System.out.println("Result ::" + result);

            output = serialPort.getOutputStream();          

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

    public synchronized void close() {
        if (serialPort != null) {
            serialPort.removeEventListener();
            serialPort.close();
        }
    }

    @Override
    public synchronized void serialEvent(SerialPortEvent oEvent) {
        if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
            try {
                String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8);
                System.out.println("Result in Serial Event::" + result);

            } catch (Exception e) {
                System.err.println(e.toString());
            }
        }

    }

    public static synchronized void writeData(String data) {
        System.out.println("Sent: " + data);
        try {
            output.write(data.getBytes());
            System.out.println("Received DATA BYTES");
        } catch (Exception e) {
            System.out.println("could not write to port");
        }
    }

    public static void main(String[] args) throws Exception {
        Serial_0306 main = new Serial_0306();
        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(1500);
                    writeData("CP");
                } catch (InterruptedException ie) {
                    ie.printStackTrace();
                }
            }
        };
        t.start();
        System.out.println("Started");
    }
}

**输出：

稳定的图书馆

Native lib Version = RXTX-2.1-7 Java lib Version = RXTX-2.1-7 入门 java.io.IOException：底层输入流返回零字节 已发送：CP 无法写入端口**

我的实际需求是从串口获取输入流并将其转换为String。 但出于测试目的，我自己发送输出流并尝试读取相同的内容。但每当我尝试读取输入流时，我都会得到异常。 我的代码是否正确？我还需要做些什么才能获得正确的输入流并将其转换为String。