Java 串口通信

在Windows系统下，用Java开发串口通信相关的程序时，需要用到几个文件。

（1）win32com.dll 要放在jdk\jre\bin目录下。

（2）comm.jar 和javax.comm.properties要放在jdk\jre\lib目录下。

下面是如何使用SerialPort的Demo：

/*
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package tina;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.TooManyListenersException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.comm.CommPortIdentifier;
import javax.comm.NoSuchPortException;
import javax.comm.PortInUseException;
import javax.comm.SerialPort;
import javax.comm.SerialPortEvent;
import javax.comm.SerialPortEventListener;
import javax.comm.UnsupportedCommOperationException;
import javax.swing.JOptionPane;

/**
 *
 * @author Tina
 */
public class DemoCom implements SerialPortEventListener {

    private static final String PORT_NAME = "COM4"; //串口号
    private static final int PORT_BAUDRATE = 115200; //波特率
    private static DemoCom instance;
    private final SerialPort mSerialPort;
    private final PrintWriter mWriter;
    private final InputStream mInputStream;
    private OnMsgArrivedListener mListener;
    private final StringBuffer buffer = new StringBuffer();

    public interface OnMsgArrivedListener {

        //收到字符
        void OnMsgArrived(char c);

    }

    private DemoCom(CommPortIdentifier portId, int baudrate) throws PortInUseException, UnsupportedCommOperationException, IOException {
        mSerialPort = (SerialPort) portId.open("DemoCom", baudrate);
        mSerialPort.setSerialPortParams(baudrate,
                SerialPort.DATABITS_8, //Data Bits
                SerialPort.STOPBITS_1, //Stop Bits
                SerialPort.PARITY_NONE); //无校验
        mSerialPort.notifyOnDataAvailable(true);

        OutputStream mOutputStream = mSerialPort.getOutputStream();
        mInputStream = mSerialPort.getInputStream();
        mWriter = new PrintWriter(mOutputStream);
    }

    public static DemoCom getInstance() {
        if (instance == null) {
            CommPortIdentifier portId;
            try {
                portId = (CommPortIdentifier) CommPortIdentifier.getPortIdentifier(PORT_NAME);
                instance = new DemoCom(portId, PORT_BAUDRATE);
            } catch (NoSuchPortException ex) {
                JOptionPane.showMessageDialog(null, "没有找到串口" + PORT_NAME + "，请确认USB线是否连接好!");
                System.exit(0);
            } catch (PortInUseException ex) {
                JOptionPane.showMessageDialog(null, "串口" + PORT_NAME + "被占用，请关闭其他可能占用的应用软件!");
                System.exit(0);
            } catch (UnsupportedCommOperationException ex) {
                JOptionPane.showMessageDialog(null, "串口" + PORT_NAME + "打开失败:" + ex.getMessage());
                System.exit(0);
            } catch (IOException ex) {
                JOptionPane.showMessageDialog(null, "串口" + PORT_NAME + "打开失败:" + ex.getMessage());
                System.exit(0);
            }
        }
        return instance;
    }

    @Override
    public void serialEvent(SerialPortEvent spe) {
        if (spe.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
            try {
                while (mInputStream.available() > 0) {
                    //处理数据
                    int c = mInputStream.read();
                    buffer.append((char) c);
                    //这里只是将数据传到其他需要监听串口数据的地方
                    if (mListener != null) {
                        mListener.OnMsgArrived((char) c);
                    }

                }
            } catch (IOException ex) {
                Logger.getLogger(PortFixture.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }

    public String sendAndGet(String command, int delayMs) {
        //发送命令
        if (mWriter != null) {
            mWriter.println(command);
            mWriter.flush();
        }
        //延时
        try {
            Thread.sleep(delayMs);
        } catch (InterruptedException ex) {
            Logger.getLogger(PortFixture.class
                    .getName()).log(Level.SEVERE, null, ex);
        }
        //查看回复的数据
        if (!buffer.toString().isEmpty()) { //如果buffer非空
            String str = buffer.toString();
            System.out.println(buffer.toString());
            buffer.delete(0, buffer.length());//读完之后清空
            return str;
        } else {
            return "";
        }
    }

    public void send(String command) {
        buffer.delete(0, buffer.length());//发送之前清空

        try {
            Thread.sleep(10);
        } catch (InterruptedException ex) {
            Logger.getLogger(PortFixture.class.getName()).log(Level.SEVERE, null, ex);
        }
        //发送命令
        if (mWriter != null) {
            mWriter.println(command);
            mWriter.flush();
        }
    }

    public void open() {
        try {
            mSerialPort.addEventListener(this);
        } catch (TooManyListenersException ex) {
            Logger.getLogger(PortFixture.class
                    .getName()).log(Level.SEVERE, null, ex);
        }

        //打开串口后，做一些处理
        if (!sendAndGet("reset", 1000).toLowerCase().contains("ok")) {
            JOptionPane.showMessageDialog(null, "无法复位!");
            System.exit(0);
        }
    }

    public void close() {
        if (mWriter != null) {
            mWriter.close();
        }

        if (mInputStream != null) {
            try {
                mInputStream.close();
            } catch (IOException ex) {
                Logger.getLogger(PortFixture.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
        if (mSerialPort != null) {
            mSerialPort.close();
        }
    }

    public void setOnMsgArrivedListener(OnMsgArrivedListener listener) {
        mListener = listener;
    }
}