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 information
return 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();
  }
}

<script type="text/javascript" src="/ChengZhong/dwr/engine.js"></script>
<script type="text/javascript" src="/ChengZhong/dwr/util.js"></script>
<script type='text/javascript' src='/ChengZhong/dwr/interface/ss.js' ></script>
<script type='text/javascript' >
 var ID;
   function begin(){
    ID=window.setInterval('get()',500); //每隔半秒自动调用 get(),取得毛重数据填入文本框中
   }
 function get()
   {
    ss.write(readIt);  //调用dwr类 Put.java 中的write方法
   }
   function readIt(Data){
    if(Data!=null && Data!="")
    {
      document.getElementById("mzBF").value=Data;
        }
   }
</script>