java的com口通讯详解编程语言

import gnu.io.CommPortIdentifier;   
import gnu.io.PortInUseException;   
import gnu.io.SerialPort;   
import gnu.io.SerialPortEvent;   
import gnu.io.SerialPortEventListener;   
import gnu.io.UnsupportedCommOperationException;   
   
import java.io.IOException;   
import java.io.InputStream;   
import java.util.Enumeration;   
import java.util.TooManyListenersException;   
   
public class SimpleRead implements Runnable, SerialPortEventListener {   
    static CommPortIdentifier portId;   
   
    static Enumeration portList;   
   
    InputStream inputStream;   
   
    SerialPort serialPort;   
   
    Thread readThread;   
   
    public static void main(String[] args) {   
   
        String com="4";   
        if(args!=null&&args.length>=1)   
        com=args[0];   
           
        portList = CommPortIdentifier.getPortIdentifiers();   
        // 检索系统串口   
        while (portList.hasMoreElements()) {   
            portId = (CommPortIdentifier) portList.nextElement();   
           
            /*如果端口类型是串口，则打印出其端口信息*/    
            if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {   
                System.out.println("------------------------");   
                System.out.println("系统可用串口: "+portId.getName());   
                System.out.println("------------------------");   
                // 指定COM口   
                if (portId.getName().equals("COM"+com)) {   
                    System.out.println("找到COM"+com+"口,初始化...");   
                    SimpleRead reader = new SimpleRead();   
                }else{   
                    System.out.println("无法找到COM"+com+"口,请重新指定...");   
                }   
            }   
        }   
    }   
   
    public SimpleRead() {   
        try {   
        // 打开COM串口 2000 设置毫秒数 超时等待时间   
           
            serialPort = (SerialPort) portId.open("SimpleReadApp", 2000);   
            System.out.println("COM口打开成功！");   
   
        } catch (PortInUseException e) {   
            System.out.println("端口被占用");   
        }   
        try {   
            inputStream = serialPort.getInputStream();   
            System.out.println("获得输入流...");   
        } catch (IOException e) {   
        }   
        //进行端口监听 , 当事件发生自动调用 serialEvent方法   
        try {   
            serialPort.addEventListener(this);   
        } catch (TooManyListenersException e) {   
        }   
        serialPort.notifyOnDataAvailable(true);   
           
        //设置通讯位   
        try {   
            System.out.println("设置通讯位...");   
            serialPort.setSerialPortParams(115200,// 设置波特率   
                    SerialPort.DATABITS_8,// 数据位数   
                    SerialPort.STOPBITS_1,// 停止位   
                    SerialPort.PARITY_NONE);// 奇偶位   
        } catch (UnsupportedCommOperationException e) {   
        }   
   
        // 启动线程，监听   
        readThread = new Thread(this);//线程负责每接收一次数据休眠20秒钟   
        readThread.start();   
    }   
   
    public void run() {   
        try {   
            System.out.println("监听...");   
            Thread.sleep(20000);//休息20秒   
               
        } catch (Exception e) {   
        }   
    }   
    // 处理侦听到的串口事件   
    public synchronized void serialEvent(SerialPortEvent event) {   
    //    System.out.println("接收数据.../r/n");   
           
        switch (event.getEventType()) {   
        case SerialPortEvent.BI://BI - 通讯中断.   
        case SerialPortEvent.OE://OE - 溢位错误.   
        case SerialPortEvent.FE://FE - 帧错误.   
        case SerialPortEvent.PE://PE - 奇偶校验错.   
        case SerialPortEvent.CD://CD - 载波检测.   
        case SerialPortEvent.CTS://CTS - 清除发送.   
        case SerialPortEvent.DSR://DSR - 数据设备准备好.   
        case SerialPortEvent.RI://RI - 　振铃指示.   
        case SerialPortEvent.OUTPUT_BUFFER_EMPTY://OUTPUT_BUFFER_EMPTY - 输出缓冲区已清空   
            break;   
        case SerialPortEvent.DATA_AVAILABLE://DATA_AVAILABLE - 有数据到达   
               
               
            byte[] readBuffer = new byte[10000];   
   
            try {   
                //读数据   
                while (inputStream.available() > 0) {   
                    int numBytes = inputStream.read(readBuffer);   
                }   
               
                String str=new String(readBuffer);   
                if(str.equals("exit")){   
                    inputStream.close();serialPort.close();   
                }   
                //输出内容   
                System.out.println("<------开始------->");   
                System.out.println(str+"==============");   
                System.out.println("<------结束------->");   
                System.out.println("                    ");   
            } catch (IOException e) {   
            }   
            break;   
        }   
    }   
}