Java实现的串口通信功能示例

package com.chengzhong.tools;import java.io.*;import javax.comm.CommPortIdentifier;import javax.comm.*;/**** This bean provides some basic functions to implement full duplex* information exchange through the serial port.**/public class SerialBean{public static String PortName;public static CommPortIdentifier portId;public static SerialPort serialPort;public static OutputStream out;public static InputStream in;//保存读数结果public static String result="";public static int openSignal=1;/**** Constructor** @param PortID the ID of the serial to be used. 1 for COM1,* 2 for COM2, etc.**/public SerialBean(int PortID){ PortName = "COM" +PortID;}/**** This function initialize the serial port for communication. It starts a* thread which consistently monitors the serial port. Any signal captured* from the serial port is stored into a buffer area.**/public int Initialize(){  openSignal=1;  try  {  portId = CommPortIdentifier.getPortIdentifier(PortName);  try  {  serialPort = (SerialPort)  portId.open("Serial_Communication", 2000);  } catch (PortInUseException e)  {    if(!SerialBean.portId.getCurrentOwner().equals("Serial_Communication"))    {      openSignal=2; //该串口被其它程序占用    }else if(SerialBean.portId.getCurrentOwner().equals("Serial_Communication")){      openSignal=1;      return openSignal;    }   return openSignal;  }  //Use InputStream in to read from the serial port, and OutputStream  //out to write to the serial port.  try  {  in = serialPort.getInputStream();  out = serialPort.getOutputStream();  } catch (IOException e)  {     openSignal=3;  //输入输出流错误     return openSignal;  }  //Initialize the communication parameters to 9600, 8, 1, none.  try  {  serialPort.setSerialPortParams(9600,  SerialPort.DATABITS_8,  SerialPort.STOPBITS_1,  SerialPort.PARITY_NONE);  } catch (UnsupportedCommOperationException e)  {     openSignal=4;  //参数不正确     return openSignal;  }  } catch (NoSuchPortException e)  {     portId=null;     openSignal=5; //没有该串口     return openSignal;  }  // when successfully open the serial port, create a new serial buffer,  // then create a thread that consistently accepts incoming signals from  // the serial port. Incoming signals are stored in the serial buffer.// return success informationreturn openSignal;}/**** This function returns a string with a certain length from the incoming* messages.** @param Length The length of the string to be returned.**/public static void ReadPort(){  SerialBean.result="";int c;try {  if(in!=null){    while(in.available()>0)    {      c = in.read();      Character d = new Character((char) c);      SerialBean.result=SerialBean.result.concat(d.toString());    }  }} catch (IOException e) {  // TODO Auto-generated catch block  e.printStackTrace();}}/**** This function sends a message through the serial port.** @param Msg The string to be sent.**/public static void WritePort(String Msg){try{  if(out!=null){    for (int i = 0; i < Msg.length(); i++)       out.write(Msg.charAt(i));  }} catch (IOException e) {  return;}}/**** This function closes the serial port in use.**/public void ClosePort(){ serialPort.close();}}

package com.chengzhong.dwr;import java.io.IOException;import com.chengzhong.tools.Arith;import com.chengzhong.tools.SerialBean;public class Put {  //2011.9.17  public String write(){    //发送指令R，仪器发送一次净重数据    SerialBean.WritePort("R");    //读取数据    SerialBean.ReadPort();    String temp=SerialBean.result.trim();  //我这里temp是形如 wn125.000kg 的数据    if(!temp.equals("") && temp.length()==11)    {       return (change(temp)).toString();    }else{      return "";    }  }  //响应开始称重  public String startWeight(String num){     int n=Integer.parseInt(num.trim());     SerialBean SB = new SerialBean(n);     SB.Initialize();     return SerialBean.openSignal+""; //返回初始化信息  }//响应停止称重  public void endWeight(){    try {      //关闭输入、输出流      SerialBean.in.close();      SerialBean.out.close();    } catch (IOException e) {      // TODO Auto-generated catch block      e.printStackTrace();    }    if(SerialBean.serialPort!=null){      SerialBean.serialPort.close(); //关闭串口    }    SerialBean.serialPort=null;    SerialBean.portId=null;    SerialBean.result="";  }  /**      * 将形如 wn125.000kg 格式的重量转换为 125.000 (kg)(四舍五入，小数点后保留两位)   */   public String change(String source){     Double result=0.0;     String s1=source.substring(2,9);     try{       result=Double.parseDouble(s1);       result=Arith.round(result,2);     }catch(Exception e){       e.printStackTrace();       return "";     }     return result.toString();   }}

package com.chengzhong.tools;import java.math.BigDecimal;/*** 由于Java的简单类型不能够精确的对浮点数进行运算，这个工具类提供精* 确的浮点数运算，包括加减乘除和四舍五入。*/public class Arith{  //默认除法运算精度  private static final int DEF_DIV_SCALE = 10;  //这个类不能实例化  private Arith(){  }  /**   * 提供精确的加法运算。   * @param v1 被加数   * @param v2 加数   * @return 两个参数的和   */  public static double add(double v1,double v2){    BigDecimal b1 = new BigDecimal(Double.toString(v1));    BigDecimal b2 = new BigDecimal(Double.toString(v2));    return b1.add(b2).doubleValue();  }  /**   * 提供精确的减法运算。   * @param v1 被减数   * @param v2 减数   * @return 两个参数的差   */  public static double sub(double v1,double v2){    BigDecimal b1 = new BigDecimal(Double.toString(v1));    BigDecimal b2 = new BigDecimal(Double.toString(v2));    return b1.subtract(b2).doubleValue();  }  /**   * 提供精确的乘法运算。   * @param v1 被乘数   * @param v2 乘数   * @return 两个参数的积   */  public static double mul(double v1,double v2){    BigDecimal b1 = new BigDecimal(Double.toString(v1));    BigDecimal b2 = new BigDecimal(Double.toString(v2));    return b1.multiply(b2).doubleValue();  }  /**   * 提供（相对）精确的除法运算，当发生除不尽的情况时，精确到   * 小数点以后10位，以后的数字四舍五入。   * @param v1 被除数   * @param v2 除数   * @return 两个参数的商   */  public static double div(double v1,double v2){    return div(v1,v2,DEF_DIV_SCALE);  }  /**   * 提供（相对）精确的除法运算。当发生除不尽的情况时，由scale参数指   * 定精度，以后的数字四舍五入。   * @param v1 被除数   * @param v2 除数   * @param scale 表示表示需要精确到小数点以后几位。   * @return 两个参数的商   */  public static double div(double v1,double v2,int scale){    if(scale<0){      throw new IllegalArgumentException(        "The scale must be a positive integer or zero");    }    BigDecimal b1 = new BigDecimal(Double.toString(v1));    BigDecimal b2 = new BigDecimal(Double.toString(v2));    return b1.divide(b2,scale,BigDecimal.ROUND_HALF_UP).doubleValue();  }  /**   * 提供精确的小数位四舍五入处理。   * @param v 需要四舍五入的数字   * @param scale 小数点后保留几位   * @return 四舍五入后的结果   */  public static double round(double v,int scale){    if(scale<0){      throw new IllegalArgumentException(        "The scale must be a positive integer or zero");    }    BigDecimal b = new BigDecimal(Double.toString(v));    BigDecimal one = new BigDecimal("1");    return b.divide(one,scale,BigDecimal.ROUND_HALF_UP).doubleValue();  }}

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