Question

我声明了一个twoWaySerialComm对象来配置端口连接。在twoWaySerialComm类中，我创建了一个线程来读取名为＆＃39; SerialReader＆＃39;的类中的传入串行数据。如何从主线程＆＃39; twoWaySerialComm＆＃39;？

访问串行数据

我已将传入的串行数据读入＆＃39; hex＆＃39; ＆＃39; SerialReader＆＃39;中的字符串一个while循环中的类。我能够在while循环中打印传入的数据，但是我无法访问这个＆＃39; hex＆＃39; ＆＃39; twoWaySerialComm＆＃39;中的字符串类。为什么我无法访问＆＃39; hex＆＃39; while循环外的字符串？如何才能做到这一点？

import gnu.io.CommPort;
import gnu.io.CommPortIdentifier;
import gnu.io.NoSuchPortException;
import gnu.io.PortInUseException;
import gnu.io.SerialPort;
import gnu.io.UnsupportedCommOperationException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author asanka
 */
public class TwoWaySerialComm {

    private static TwoWaySerialComm twoWaySerialComm;

    String read;

    private TwoWaySerialComm() throws NoSuchPortException, PortInUseException, UnsupportedCommOperationException, IOException {
        String portName = "/dev/ttyUSB0";
        CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(portName);
        if (portIdentifier.isCurrentlyOwned()) {
            System.out.println("Error: Port is currently in use");
        } else {
            CommPort commPort = portIdentifier.open(this.getClass().getName(), 2000);

            if (commPort instanceof SerialPort) {
                SerialPort serialPort = (SerialPort) commPort;
                serialPort.setSerialPortParams(115200, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);

                InputStream in = serialPort.getInputStream();
                OutputStream out = serialPort.getOutputStream();

                SerialReader reader;
                (new Thread(reader = new SerialReader(in))).start();
                read = reader.readHex();

            } else {
                System.out.println("Error: Only serial ports are handled by this example.");
            }
        }
    }

    public static TwoWaySerialComm getTwoWaySerialComm() throws NoSuchPortException, PortInUseException, UnsupportedCommOperationException, IOException {
        if (twoWaySerialComm == null) {
            twoWaySerialComm = new TwoWaySerialComm();
        }
        return twoWaySerialComm;
    }

    public String data() {
        return read;
    }

    /**
     *
     */
    public static class SerialReader implements Runnable {

        String hex;
        InputStream in;

        public SerialReader(InputStream in) {
            this.in = in;
        }

        public void run() {
            byte[] buffer = new byte[1024];

            int len;
            try {
                while ((len = this.in.read(buffer)) > -1) {

                    hex = new String(buffer, 0, len).replaceAll("\\s", "");
                    Thread.sleep(1000);
                    System.out.println(hex);
                }

            } catch (IOException e) {
                e.printStackTrace();
            } catch (InterruptedException ex) {
                Logger.getLogger(TwoWaySerialComm.class.getName()).log(Level.SEVERE, null, ex);
            }
        }

        public String readHex() {
            return hex;
        }
    }

    /**
     *
     */
    public static class SerialWriter implements Runnable {

        OutputStream out;

        public SerialWriter(OutputStream out) {
            this.out = out;
        }

        public void run() {
            try {
                int c = 0;
                while ((c = System.in.read()) > -1) {
                    this.out.write(c);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

}

Answer 1

据我所知，您正在另一个Thread中运行读取操作。在调用readHex（）方法时，该Thread可能尚未填充hex字段。

首先需要在新线程上调用join（），以确保它已完成。或者使用java.util.concurrent包中的CompletableFuture。

双向串行通信 - 无法访问串行读取器线程中的字符串读取

1 个答案: