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：

/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
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;
}
}