java操作串口通信

最近接触了modbus串口通信，记录一下，方便以后使用。

1. 下载动态链接库:rxtx-for-java 、

Windows

Copy RXTXcomm.jar ---> <JAVA_HOME>\jre\lib\ext
Copy rxtxSerial.dll ---> <JAVA_HOME>\jre\bin
Copy rxtxParallel.dll ---> <JAVA_HOME>\jre\bin

linux

Copy RXTXcomm.jar ---> <JAVA_HOME>/jre/lib/ext
Copy librxtxSerial.so ---> <JAVA_HOME>/jre/lib/i386/
Copy librxtxParallel.so ---> <JAVA_HOME>/jre/lib/i386/

注：如果运行过程中抛出 java.lang.UnsatisfiedLinkError 错误或 gnu.io 下的类找不到，请将rxtx解压包中的 rxtxParallel.dll，rxtxSerial.dll 这两个文件复制到 C:\Windows\System32 目录下即可解决该错误。

2. maven依赖：

<dependency>
    <groupId>org.rxtx</groupId>
    <artifactId>rxtx</artifactId>
    <version>2.1.7</version>
</dependency>
<dependency>
    <groupId>org.bidib.jbidib.org.qbang.rxtx</groupId>
    <artifactId>rxtxcomm</artifactId>
    <version>2.2</version>
</dependency>

3. Examples

demo:查询所有串口

package com.wekri.modbus.rtu;

import gnu.io.CommPort;
import gnu.io.CommPortIdentifier;
import gnu.io.PortInUseException;

import java.util.Enumeration;
import java.util.HashSet;

/**
 * Discovering available comm ports
 * Created by liuweiguo on 2018/4/10.
 */
public class DiscoveringPorts {
    public static void main(String[] args) {
        HashSet<CommPortIdentifier> set = getAvailableSerialPorts();
        System.out.println("total:" + set.size());

        for (CommPortIdentifier a : set) {
            System.out.println(a.getName());
        }

        System.out.println("finish");
    }

    /**
     * @return    A HashSet containing the CommPortIdentifier for all serial ports that are not currently being used.
     */
    public static HashSet<CommPortIdentifier> getAvailableSerialPorts() {
        HashSet<CommPortIdentifier> h = new HashSet<>();
        Enumeration thePorts = CommPortIdentifier.getPortIdentifiers();
        while (thePorts.hasMoreElements()) {
            CommPortIdentifier com = (CommPortIdentifier) thePorts.nextElement();
            switch (com.getPortType()) {
                case CommPortIdentifier.PORT_SERIAL:
                    try {
                        CommPort thePort = com.open("CommUtil", 50);
                        thePort.close();
                        h.add(com);
                    } catch (PortInUseException e) {
                        System.out.println("Port, "  + com.getName() + ", is in use.");
                    } catch (Exception e) {
                        System.err.println("Failed to open port " +  com.getName());
                        e.printStackTrace();
                    }
            }
        }
        return h;
    }
}

demo2：连接串口

package com.wekri.modbus.rtu;

import gnu.io.CommPort;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Created by liuweiguo on 2018/4/10.
 */
public class TwoWaySerialComm {
    public TwoWaySerialComm() {
        super();
    }

    void connect(String portName) throws Exception {
        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(57600, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);

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

                (new Thread(new SerialReader(in))).start();
                (new Thread(new SerialWriter(out))).start();

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

    /** */
    public static class SerialReader implements Runnable {
        InputStream in;

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

        public void run() {
            byte[] buffer = new byte[1024];
            int len = -1;
            try {
                while ((len = this.in.read(buffer)) > -1) {
                    System.out.print(new String(buffer, 0, len));
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /** */
    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();
            }
        }
    }

    public static void main(String[] args) {
        try {
//            new TwoWaySerialComm().connect("COM3");
            new TwoWaySerialComm().connect("COM2");
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

参考文档：

http://rxtx.qbang.org/wiki/index.php/Main_Page