Picses' sky

一個(gè)嵌入式系統(tǒng)通常需要通過(guò)串口與其主控系統(tǒng)進(jìn)行全雙工通訊，譬如一個(gè)流水線
控制系統(tǒng)需要不斷的接受從主控系統(tǒng)發(fā)送來(lái)的查詢和控制信息，并將執(zhí)行結(jié)果或查
詢結(jié)果發(fā)送回主控系統(tǒng)。本文介紹了一個(gè)簡(jiǎn)單的通過(guò)串口實(shí)現(xiàn)全雙工通訊的Java類
庫(kù)，該類庫(kù)大大的簡(jiǎn)化了對(duì)串口進(jìn)行操作的過(guò)程。

本類庫(kù)主要包括：SerialBean.java (與其他應(yīng)用程序的接口), SerialBuffer.java
(用來(lái)保存從串口所接收數(shù)據(jù)的緩沖區(qū)), ReadSerial.java (從串口讀取數(shù)據(jù)的程序)。
另外本類庫(kù)還提供了一個(gè)例程SerialExample.java 作為示范。在下面的內(nèi)容中將逐
一對(duì)這幾個(gè)部分進(jìn)行詳細(xì)介紹。

1. SerialBean

SerialBean是本類庫(kù)與其他應(yīng)用程序的接口。該類庫(kù)中定義了SerialBean的構(gòu)造方
法以及初始化串口，從串口讀取數(shù)據(jù)，往串口寫(xiě)入數(shù)據(jù)以及關(guān)閉串口的函數(shù)。具體
介紹如下：

public SerialBean(int PortID)

本函數(shù)構(gòu)造一個(gè)指向特定串口的SerialBean，該串口由參數(shù)PortID所指定。
PortID = 1 表示COM1，PortID = 2 表示COM2，由此類推。

public int Initialize()

本函數(shù)初始化所指定的串口并返回初始化結(jié)果。如果初始化成功返回1，否
則返回-1。初始化的結(jié)果是該串口被SerialBean獨(dú)占性使用，其參數(shù)被設(shè)置
為9600, N, 8, 1。如果串口被成功初始化，則打開(kāi)一個(gè)進(jìn)程讀取從串口傳
入的數(shù)據(jù)并將其保存在緩沖區(qū)中。

public String ReadPort(int Length)

本函數(shù)從串口(緩沖區(qū))中讀取指定長(zhǎng)度的一個(gè)字符串。參數(shù)Length指定所返
回字符串的長(zhǎng)度。

public void WritePort(String Msg)

本函數(shù)向串口發(fā)送一個(gè)字符串。參數(shù)Msg是需要發(fā)送的字符串。

public void ClosePort()

本函數(shù)停止串口檢測(cè)進(jìn)程并關(guān)閉串口。

SerialBean的源代碼如下：

package serial;

import java.io.*;
import java.util.*;
import javax.comm.*;

/**
*
* This bean provides some basic functions to implement full dulplex
* information exchange through the srial port.
*
*/

public class SerialBean
{

static String PortName;
CommPortIdentifier portId;
SerialPort serialPort;
static OutputStream out;
static InputStream in;

SerialBuffer SB;
ReadSerial RT;

/**
*
* 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()
{

int InitSuccess = 1;
int InitFail = -1;

try
{

portId = CommPortIdentifier.getPortIdentifier(PortName);

try
{
serialPort = (SerialPort)
portId.open("Serial_Communication", 2000);
} catch (PortInUseException e)
{
return InitFail;
}

//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)
{
return InitFail;
}

//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)
{
return InitFail;
}
} catch (NoSuchPortException e)
{
return InitFail;
}

// 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.

SB = new SerialBuffer();
RT = new ReadSerial(SB, in);
RT.start();

// return success information

return InitSuccess;
}

/**
*
* This function returns a string with a certain length from the incoming
* messages.
*
* @param Length The length of the string to be returned.
*
*/

public String ReadPort(int Length)
{
String Msg;
Msg = SB.GetMsg(Length);
return Msg;
}

/**
*
* This function sends a message through the serial port.
*
* @param Msg The string to be sent.
*
*/

public void WritePort(String Msg)
{
int c;
try
{
for (int i = 0; i < Msg.length(); i++)
out.write(Msg.charAt(i));
} catch (IOException e) {}
}

/**
*
* This function closes the serial port in use.
*
*/

public void ClosePort()
{
RT.stop();
serialPort.close();
}
}

2. SerialBuffer

SerialBuffer是本類庫(kù)中所定義的串口緩沖區(qū)，它定義了往該緩沖區(qū)中寫(xiě)入數(shù)據(jù)和
從該緩沖區(qū)中讀取數(shù)據(jù)所需要的函數(shù)。

public synchronized String GetMsg(int Length)

本函數(shù)從串口(緩沖區(qū))中讀取指定長(zhǎng)度的一個(gè)字符串。參數(shù)Length指定所
返回字符串的長(zhǎng)度。

public synchronized void PutChar(int c)

本函數(shù)望串口緩沖區(qū)中寫(xiě)入一個(gè)字符，參數(shù)c 是需要寫(xiě)入的字符。

在往緩沖區(qū)寫(xiě)入數(shù)據(jù)或者是從緩沖區(qū)讀取數(shù)據(jù)的時(shí)候，必須保證數(shù)據(jù)的同
步，因此GetMsg和PutChar函數(shù)均被聲明為synchronized并在具體實(shí)現(xiàn)中采
取措施實(shí)現(xiàn)的數(shù)據(jù)的同步。

SerialBuffer的源代碼如下：

package serial;

/**
*
* This class implements the buffer area to store incoming data from the serial
* port.
*
*/

public class SerialBuffer
{
private String Content = "";
private String CurrentMsg, TempContent;
private boolean available = false;
private int LengthNeeded = 1;

/**
*
* This function returns a string with a certain length from the incoming
* messages.
*
* @param Length The length of the string to be returned.
*
*/

public synchronized String GetMsg(int Length)
{
LengthNeeded = Length;
notifyAll();

if (LengthNeeded > Content.length())
{
available = false;
while (available == false)
{
try
{
wait();
} catch (InterruptedException e) { }
}
}

CurrentMsg = Content.substring(0, LengthNeeded);
TempContent = Content.substring(LengthNeeded);
Content = TempContent;
LengthNeeded = 1;
notifyAll();
return CurrentMsg;
}

/**
*
* This function stores a character captured from the serial port to the
* buffer area.
*
* @param t The char value of the character to be stored.
*
*/

public synchronized void PutChar(int c)
{
Character d = new Character((char) c);
Content = Content.concat(d.toString());
if (LengthNeeded < Content.length())
{
available = true;
}
notifyAll();
}
}

3. ReadSerial

ReadSerial是一個(gè)進(jìn)程，它不斷的從指定的串口讀取數(shù)據(jù)并將其存放到緩沖區(qū)中。

public ReadSerial(SerialBuffer SB, InputStream Port)

本函數(shù)構(gòu)造一個(gè)ReadSerial進(jìn)程，參數(shù)SB指定存放傳入數(shù)據(jù)的緩沖區(qū)，參
數(shù)Port指定從串口所接收的數(shù)據(jù)流。

public void run()

ReadSerial進(jìn)程的主函數(shù)，它不斷的從指定的串口讀取數(shù)據(jù)并將其存放到
緩沖區(qū)中。

ReadSerial的源代碼如下：

package serial;

import java.io.*;

/**
*
* This class reads message from the specific serial port and save
* the message to the serial buffer.
*
*/

public class ReadSerial extends Thread
{
private SerialBuffer ComBuffer;
private InputStream ComPort;

/**
*
* Constructor
*
* @param SB The buffer to save the incoming messages.
* @param Port The InputStream from the specific serial port.
*
*/

public ReadSerial(SerialBuffer SB, InputStream Port)
{
ComBuffer = SB;
ComPort = Port;
}

public void run()
{
int c;
try
{
while (true)
{
c = ComPort.read();
ComBuffer.PutChar(c);
}
} catch (IOException e) {}
}
}

4. SerialExample

SerialExample是本類庫(kù)所提供的一個(gè)例程。它所實(shí)現(xiàn)的功能是打開(kāi)串口COM1，對(duì)
其進(jìn)行初始化，從串口讀取信息對(duì)其進(jìn)行處理后將處理結(jié)果發(fā)送到串口。

import serial.*;
import java.io.*;

/**
*
* This is an example of how to use the SerialBean. It opens COM1 and reads
* six messages with different length form the serial port.
*
*/

class SerialExample
{
public static void main(String[] args)
{
//TO DO: Add your JAVA codes here

SerialBean SB = new SerialBean(1);
String Msg;

SB.Initialize();
for (int i = 5; i <= 10; i++)
{
Msg = SB.ReadPort(i);
SB.WritePort("Reply: " + Msg);
}
SB.ClosePort();
}
}

5. 編譯與調(diào)試

本類庫(kù)中使用了Java Communication API (javax.comm)。這是一個(gè)Java擴(kuò)展類庫(kù)，
并不包括在標(biāo)準(zhǔn)的Java SDK當(dāng)中。如果你尚未安裝這個(gè)擴(kuò)展類庫(kù)的話，你應(yīng)該從Sun
公司的Java站點(diǎn)下載這個(gè)類庫(kù)并將其安裝在你的系統(tǒng)上。在所下載的包里面包括一個(gè)
安裝說(shuō)明，如果你沒(méi)有正確安裝這個(gè)類庫(kù)及其運(yùn)行環(huán)境的話，運(yùn)行這個(gè)程序的時(shí)候你
會(huì)找不到串口。

正確安裝Java Communication API并將上述程序編譯通過(guò)以后，你可以按如下方法測(cè)
試這個(gè)程序。如果你只有一臺(tái)機(jī)器，你可以利用一條RS-232電纜將COM1和COM2連接起
來(lái)，在COM1上運(yùn)行SerialExample，在COM2上運(yùn)行Windows提供的超級(jí)終端程序。如果
你有兩臺(tái)機(jī)器的話，你可以利用一條RS-232電纜將兩臺(tái)機(jī)器的COM1(或者是COM2)連接
起來(lái)，在一端運(yùn)行例程，另外一端運(yùn)行Windows提供的超級(jí)終端程序。如果有必要的
話，可以對(duì)SerialExample中所聲明的串口進(jìn)行相應(yīng)改動(dòng)。

本程序在Windows 2000 + Java SDK 1.3環(huán)境下編譯通過(guò)并成功運(yùn)行。

　　以下是用Java讀取串口的程序。

這個(gè)簡(jiǎn)單的程序包括以下文件：

       IMU.java (主程序)
       ReadBuffer.java (從緩沖區(qū)讀取一個(gè)消息)
       ReadSerial.java (讀取串口數(shù)據(jù)并放入緩沖區(qū))
       SerialBuffer.java (緩沖區(qū))
       WriteSerial.java (不斷的往串口送星號(hào)'*')

測(cè)試程序：

       SendCom.java (將一個(gè)數(shù)據(jù)文件往串口發(fā)送)
       SEND.TXT (供測(cè)試用的數(shù)據(jù)文件)

在這個(gè)通訊程序中使用了一個(gè)簡(jiǎn)單的協(xié)議，既不同的消息之間用星號(hào)'*'作為分隔。這個(gè)程序中的問(wèn)題是ReadSerial進(jìn)程和WriteSerial進(jìn)程不能夠同時(shí)啟動(dòng)，出錯(cuò)信息是不能夠打開(kāi)串口，因?yàn)橥瑯右粋€(gè)串口不能夠同時(shí)被打開(kāi)兩次(在ReadSerial中聲明了FileReader和在WriteSerial中聲明了FileWriter)。這樣是不能夠?qū)崿F(xiàn)全雙工通訊的。

/*
*
* IMU.java 1.0
* Main Program for Serial Communication
*
* Created: March 27, 2001
*
* Author : Qingye Jiang (John)
* American GNC Corporation
* 888 Easy St, Simi Valley CA 93065-1812
*
* Contact: (805) 582-0582 (Tel), (805) 582-0098 (Fax)
* qjiang@tsinghua.edu
*
*/

import java.io.*;

class IMU
{
       public static void main(String[] args)
       {
               //TO DO: Add your JAVA codes here

               File ComPort = new File("COM1");

       SerialBuffer SB = new SerialBuffer();
       ReadSerial r1 = new ReadSerial(SB, ComPort);
       ReadBuffer r2 = new ReadBuffer(SB);
       WriteSerial r3 = new WriteSerial(ComPort);

       r1.start();
       r2.start();
       r3.start();
   }
}

/*
*
* ReadBuffer.java 1.0
* Program to Read the Serial Buffer
*
* Created: March 27, 2001
*
* Author : Qingye Jiang (John)
* American GNC Corporation
* 888 Easy St, Simi Valley CA 93065-1812
*
* Contact: (805) 582-0582 (Tel), (805) 582-0098 (Fax)
* qjiang@tsinghua.edu

*
*/

import java.io.*;

public class ReadBuffer extends Thread
{
   private SerialBuffer ComBuffer;

   public ReadBuffer(SerialBuffer SB)
   {
       ComBuffer = SB;
   }

   public void run()
   {
               String Msg;

       while (true)
       {
               Msg = ComBuffer.GetMsg();
               System.out.println(Msg);
       }

   }
}

/*
*
* ReadSerial.java 1.0
* Program to read characters from the serial port and put it
* to the buffer
*
* Created: March 27, 2001
*
* Author : Qingye Jiang (John)
* American GNC Corporation
* 888 Easy St, Simi Valley CA 93065-1812
*
* Contact: (805) 582-0582 (Tel), (805) 582-0098 (Fax)
*       qjiang@tsinghua.edu
*
*/

import java.io.*;

public class ReadSerial extends Thread
{
   private SerialBuffer ComBuffer;
   private File ComPort;

   public ReadSerial(SerialBuffer SB, File Port)
   {
       ComBuffer = SB;
       ComPort = Port;
   }

   public void run()
   {
               int c;
               try
               {
                       FileReader in = new FileReader(ComPort);

while (true)
           {
               c = in.read();
               ComBuffer.PutChar(c);
           }
               try
               {
                       FileReader in = new FileReader(ComPort);
               while (true)
           {
               c = in.read();

               ComBuffer.PutChar(c);
           }
       } catch (IOException e) {}
   }
}

/*
*
* SerialBuffer.java 1.0
* Class that implements the serial buffer
*
* Created: March 27, 2001
*
* Author : Qingye Jiang (John)
*   American GNC Corporation
* 888 Easy St, Simi Valley CA 93065-1812
*
* Contact: (805) 582-0582 (Tel), (805) 582-0098 (Fax)
* qjiang@tsinghua.edu

*
*/

public class SerialBuffer
{
   private String Content = "";
   private String CurrentMsg, TempContent;
   private boolean available = false;

   public synchronized String GetMsg()
   {
       int SepMark;

       if ((SepMark = Content.indexOf('*')) == -1)
       {
               available = false;
               while (available == false)
               {
               try
               {
                   wait();
               } catch (InterruptedException e) { }
               }
               SepMark = Content.indexOf('*');
       }

       CurrentMsg = Content.substring(0, SepMark);
       TempContent = Content.substring(SepMark+1);
       Content = TempContent;
       notifyAll();
       return CurrentMsg;
   }

   public synchronized void PutChar(int c)
   {
       Character d = new Character((char) c);
       Content = Content.concat(d.toString());
       if (c == '*')
       {
               available = true;
       }
       notifyAll();
   }
}

/*
*
* WriteSerial.java 1.0
* Program to send a character to the serial port
*
* Created: March 27, 2001
*
* Author : Qingye Jiang (John)
* American GNC Corporation
* 888 Easy St, Simi Valley CA 93065-1812
*
* Contact: (805) 582-0582 (Tel), (805) 582-0098 (Fax)
* qjiang@tsinghua.edu
*
*/

import java.io.*;

public class WriteSerial extends Thread
{
   private SerialBuffer ComBuffer;
   private File ComPort;

   public WriteSerial(File Port)
   {
       ComPort = Port;
   }

   public void run()
   {
               int c;
               try
               {
                       FileWriter out = new FileWriter(ComPort);
               while (true)
           {
               out.write('*');
           }
       } catch (IOException e)
       {
               System.out.println(e.getMessage());
       }
   }
}

import java.io.*;

public class SendCom
{
   public static void main(String[] args)
   {

               File OutFile = new File("SEND.TXT");
               File ComPort = new File("COM2");

               int c;

               try
               {
                       FileReader in = new FileReader(OutFile);
                       FileWriter out = new FileWriter(ComPort);
                       while ((c = in.read()) != -1)
                               out.write(c);
                       in.close();
                       out.close();
               } catch (IOException e) {}

       }
}

 

SEND.TXT*

This is a sample of the data file for program testing. *

It should be in the same directory as the SendCom.class file.*

When you run this sample program, connect your COM1 and COM2 with a
serial cable so that you can test this program on one machine. If
you have two machines, you can connect the two machine via a serial
cable and test it. Modified the definition of ComPort in the program
if necessary. *

Thank you for testing this program. If you have any suggestions please
kindly let me know. *

這是一個(gè)通過(guò)JAVA的擴(kuò)展包(javax.comm)從串口讀取值的類，
  本類庫(kù)(javax.comm)主要包括：
 SerialBean.java (與其他應(yīng)用程序的接口),
 SerialBuffer.java (用來(lái)保存從串口所接收數(shù)據(jù)的緩沖區(qū)),
 ReadSerial.java (從串口讀取數(shù)據(jù)的程序)。

 整個(gè)類的設(shè)計(jì)思路大概就是：
 實(shí)現(xiàn)一個(gè)線程一直在監(jiān)聽(tīng)串口中是否有數(shù)據(jù)傳送過(guò)來(lái)，
 如果有的話開(kāi)始拍照，并取得照片后，直接打印出來(lái)。因?yàn)樯婕暗缴虡I(yè)秘密，所以拍照函數(shù)和取得照片函數(shù)采用的是空函數(shù)，請(qǐng)見(jiàn)諒!
 若要運(yùn)行此函數(shù)必須下載該擴(kuò)展包，并加載到你的CLASSPATH下。當(dāng)然，你若要測(cè)試并運(yùn)行此類的話。可能要花費(fèi)不少的精力。
 如果你只有一臺(tái)機(jī)器，你可以利用一條RS-232電纜將COM1和COM2連接起來(lái)，在COM1上運(yùn)行SerialExample，在COM2上運(yùn)行Windows提供的超級(jí)終端程序。
 如果你有兩臺(tái)機(jī)器的話，你可以利用一條RS-232電纜將兩臺(tái)機(jī)器的COM1(或者是COM2)連接起來(lái)，在一端運(yùn)行例程，另外一端運(yùn)行Windows提供的超級(jí)終端程序。
 
該類有相當(dāng)詳細(xì)的注釋。我想應(yīng)該不難理解吧!

import java.io.*;
import java.awt.*;
import java.awt.print.*;
import javax.print.*;
import javax.comm.*; //這是一個(gè)Java擴(kuò)展類庫(kù)，并不包括在標(biāo)準(zhǔn)的Java SDK當(dāng)中。
//如果你尚未安裝這個(gè)擴(kuò)展類那么你需要到sun公司的Java站點(diǎn)下載這個(gè)類庫(kù)

class SuanKou implements Runnable{
  private java.io.FileOutputStream fos=null;
  private Thread th=null;
  private long shiJian=500;//設(shè)置間隔的時(shí)間
   //private int duanKou=1;//設(shè)置端口號(hào)
   private String Msg = null;
   private SerialBean SB=null;
   private int isSucces=-1;
 
   //構(gòu)造函數(shù)
  public SuanKou(long sj,int dk) {
    System.out.println("構(gòu)造函數(shù)");
    try{
    fos=new java.io.FileOutputStream("c:\\log.txt");
   
    this.shiJian=sj;//設(shè)定監(jiān)聽(tīng)端口的時(shí)間
   
    //this.duanKou=dk;//端口號(hào)
   
    SB = new SerialBean(dk);//創(chuàng)建一個(gè)接口對(duì)象，參數(shù)為端口號(hào)
   
   isSucces = SB.Initialize();//初使化所指定的串口并返回初始化結(jié)果。如果初始化成功返回1，否則返回-1
  
    th=new Thread(this);//創(chuàng)建一個(gè)線程對(duì)象
  
    th.start();//創(chuàng)建SuanKou這個(gè)對(duì)象就開(kāi)始啟動(dòng)線程
 }catch(java.io.FileNotFoundException fe){
  fe.printStackTrace();
 }catch(Exception e){
  e.printStackTrace();
 }
  }

//拍照函數(shù)
  public void snape() {
    System.out.println("拍照函數(shù)");
  }

//取得照片函數(shù)
  public void getPicture() {
    System.out.println("取得照片函數(shù)");

  }
 
  //實(shí)現(xiàn)線程接口的RUN方法
  public void run(){
    Thread.sleep(shiJian);
    this.ReadSuanKou();
  }
 
  //定期到串口讀取數(shù)據(jù)和函數(shù)，如果能讀到數(shù)據(jù)就調(diào)用snape(),getPicture(),函數(shù)，寫(xiě)日志，打印
  private void ReadSuanKou() {
  
   //如果初使化成功的話，
    if (isSucces == 1) {
    
      //從串口(緩沖區(qū))中讀取指定長(zhǎng)度的一個(gè)字符串。(500)
     
      try{
      
      Msg = SB.ReadPort(500);

      //如果可以從串口讀到數(shù)據(jù)的話

      if (Msg != null) {
        this.snape();//調(diào)用拍照函數(shù)
       
        this.getPicture();//調(diào)用取得照片函數(shù)
       
        java.text.SimpleDateFormat df=new java.text.SimpleDateFormat("EEEE-MMMM-dd-yyyy");

 Date date=new Date();

 String dateFormat=df.format(date);
 
        fos.write(dateFormat.getBytes());//在日志文件中記錄當(dāng)前時(shí)間
       
        fos.write(Msg.getBytes());//將讀到的數(shù)據(jù)寫(xiě)到日志文件中
 
  //調(diào)用打印方法 注：若要打印，要打印的對(duì)象必須實(shí)現(xiàn)java.awt.print.Printable接口。即getPicture
 
  //返回的對(duì)象必須實(shí)現(xiàn)該接口,因?yàn)椴恢纆etPicture返回什么對(duì)象，故這個(gè)打印功能無(wú)法實(shí)現(xiàn)，不過(guò)大概的思路是
 
  /** 1,需要一個(gè)打印服務(wù)對(duì)象。這可通過(guò)三種方式實(shí)現(xiàn)：
      在jdk1.4之前的版本，必須要實(shí)現(xiàn)java.awt.print.Printable接口
      或通過(guò)Toolkit.getDefaultToolkit().getPrintJob來(lái)獲取打印服務(wù)對(duì)象；
      在jdk1.4中則還可以通過(guò)javax.print.PrintSerivceLookup來(lái)查找定位一個(gè)打印服務(wù)對(duì)象。

　　                2、需要開(kāi)始一個(gè)打印工作。這也有幾種實(shí)現(xiàn)方法：在jdk1.4之前可以通過(guò)java.awt.print.PrintJob
   （jdk1.1提供的，現(xiàn)在已經(jīng)很少用了）調(diào)用print或printAll方法開(kāi)始打印工作；
   也可以通過(guò)java.awt.print.PrinterJob的printDialog顯示打印對(duì)話框，
   然后通過(guò)print方法開(kāi)始打印；在jdk1.4中則可以通過(guò)javax.print.ServiceUI的printDialog顯示打印對(duì)話框，
   然后調(diào)用print方法開(kāi)始一個(gè)打印工作。
 
  根據(jù)以上的提示去做，不會(huì)很難!
  */
 
  java.awt.print.PrinterJob pj=new java.awt.print.PrinterJob();
 
  pj.printDialog();//顯示打印對(duì)話框
  pj.print();//開(kāi)始打印
 
      }

      //SB.WritePort("OK");若要向串口返回一個(gè)結(jié)果可以調(diào)用該函數(shù)?

     
 }catch(Exception e){
 
  e.printStackTrace();

 }finally{
  try{
   fos.close();
    //停止串口檢測(cè)進(jìn)程并關(guān)閉串口。
        SB.ClosePort();
     
  }catch(Exception e){
   e.printStackTrace();
  }
 }

    }
    else {
      throw RuntimeException("讀取串口數(shù)據(jù)時(shí)出錯(cuò)!");
    }

  }

 

  //主函數(shù)
  public static void main(String args[]) {
  
    new SuanKou(1000,1);//參數(shù)為間隔的時(shí)間,和端口號(hào)

  }
}

 

本文介紹一個(gè)利用Java Comm API (javax.comm)實(shí)現(xiàn)串口全雙工通訊的簡(jiǎn)單程序。這個(gè)程序首先打開(kāi)并初始化一個(gè)串口，然后啟動(dòng)如下三個(gè)進(jìn)程：ReadSerial進(jìn)程從該串口讀取數(shù)據(jù)并放入緩沖區(qū)，ReadBuffer進(jìn)程從緩沖區(qū)讀取數(shù)據(jù)并打印到屏幕， WriteSerial進(jìn)程每5秒鐘向該串口發(fā)送一個(gè)星號(hào)(*)。

在這個(gè)示例程序中使用了一個(gè)簡(jiǎn)單的協(xié)議，既不同的消息之間用星號(hào)'*'作為分隔。緩沖區(qū)程序根據(jù)是否收到星號(hào)作為存在等待處理的消息的判斷依據(jù)。

Java Comm API不是標(biāo)準(zhǔn)的Java API，因此的標(biāo)準(zhǔn)的運(yùn)行環(huán)境中并不提供這個(gè)包。如果你的系統(tǒng)上還沒(méi)有安裝這個(gè)包，你可以從SUN公司的網(wǎng)站下載。在這個(gè)包里面有一個(gè)安裝指南，如果你沒(méi)有正確安裝這個(gè)包，可能你不能夠正確運(yùn)行這個(gè)例程。

這個(gè)簡(jiǎn)單的例程包括以下文件：

IMU.java (主程序)
ReadBuffer.java (從緩沖區(qū)讀取一個(gè)消息)
ReadSerial.java (讀取串口數(shù)據(jù)并放入緩沖區(qū))
SerialBuffer.java (緩沖區(qū))
WriteSerial.java (每5秒鐘往串口送一個(gè)星號(hào)'*')

測(cè)試程序：

SendCom.java (將一個(gè)數(shù)據(jù)文件往串口發(fā)送)
SEND.TXT (供測(cè)試用的數(shù)據(jù)文件)

測(cè)試方法：

1 正確安裝Java Comm API后編譯本例程
2 將計(jì)算機(jī)的COM1和COM2用一條串口線連接起來(lái)
3 運(yùn)行IMU。如果你這時(shí)候打開(kāi)Windows自帶的超級(jí)終端并連接到COM2的話，你應(yīng)該能夠看見(jiàn)有星號(hào)出現(xiàn)在超級(jí)終端的屏幕上。超級(jí)終端的參數(shù)設(shè)置為9600, N, 8, 1, none。
4 關(guān)閉超級(jí)終端，運(yùn)行SendCom。這時(shí)候你應(yīng)該能夠從IMU的屏幕上看到數(shù)據(jù)文件里面的內(nèi)容。

/*
*
* IMU.java 1.0
* Main Program for Serial Communication
*
* Created: March 27, 2001
*
* Author : Qingye Jiang (John)
* American GNC Corporation
* 888 Easy St, Simi Valley CA 93065-1812
*
* Contact: (805) 582-0582 (Tel), (805) 582-0098 (Fax)
* qjiang@tsinghua.edu
*
*/

import java.io.*;
import java.util.*;
import javax.comm.*;

class IMU
{

static CommPortIdentifier portId;
static SerialPort serialPort;
static OutputStream out;
static InputStream in;

public static void main(String[] args)
{

try
{

//Declare the serial port, and open it.

portId = CommPortIdentifier.getPortIdentifier("COM1");
try
{

serialPort = (SerialPort) portId.open("IMU_App", 2000);

} catch (PortInUseException e)
{

System.out.println(e.getMessage());

}

//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)
{

System.out.println(e.getMessage());

}

//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)
{

System.out.println(e.getMessage());

}

} catch (NoSuchPortException e)
{

System.out.println(e.getMessage());

}

//Declare the serial buffer area, a thread to read from the seriial port,
//a thread to read from the serial buffer for processing, and a thread
//to write to the serial port.

SerialBuffer SB = new SerialBuffer();
ReadSerial r1 = new ReadSerial(SB, in);
ReadBuffer r2 = new ReadBuffer(SB);
WriteSerial r3 = new WriteSerial(out);

//Start all three threads.

r1.start();
r2.start();
r3.start();

}

}

/*
*
* SerialBuffer.java 1.0
* Class that implements the serial buffer
*
* Created: March 27, 2001
*
* Author : Qingye Jiang (John)
* American GNC Corporation
* 888 Easy St, Simi Valley CA 93065-1812
*
* Contact: (805) 582-0582 (Tel), (805) 582-0098 (Fax)
* qjiang@tsinghua.edu
*
*/

public class SerialBuffer
{

private String Content = "";
private String CurrentMsg, TempContent;
private boolean available = false;


//read a message from the serial buffer. The star character '*' is used
//as the seperation mark between different messages.

public synchronized String GetMsg()
{

int SepMark;

if ((SepMark = Content.indexOf('*')) == -1)
{

available = false;
while (available == false)
{

try
{
        wait();
} catch (InterruptedException e) { }

}
SepMark = Content.indexOf('*');

}

CurrentMsg = Content.substring(0, SepMark);
TempContent = Content.substring(SepMark+1);
Content = TempContent;
notifyAll();
return CurrentMsg;

}

//Put a character to the serial buffer

public synchronized void PutChar(int c)
{

Character d = new Character((char) c);
Content = Content.concat(d.toString());
if (c == '*')
{
        available = true;
}
notifyAll();

}

}

/*
*
* ReadSerial.java 1.0
* Program to read characters from the serial port and put it
* to the buffer
*
* Created: March 27, 2001
*
* Author : Qingye Jiang (John)
* American GNC Corporation
* 888 Easy St, Simi Valley CA 93065-1812
*
* Contact: (805) 582-0582 (Tel), (805) 582-0098 (Fax)
* qjiang@tsinghua.edu
*
*/

import java.io.*;

public class ReadSerial extends Thread
{

private SerialBuffer ComBuffer;
private InputStream ComPort;

public ReadSerial(SerialBuffer SB, InputStream Port)
{
        ComBuffer = SB;
        ComPort = Port;
}

public void run()
{

int c;
try
{

while (true)
{
        c = ComPort.read();
        ComBuffer.PutChar(c);
}

} catch (IOException e) {}

}

}

/*
*
* ReadBuffer.java 1.0
* Program to Read the Serial Buffer
*
* Created: March 27, 2001
*
* Author : Qingye Jiang (John)
* American GNC Corporation
* 888 Easy St, Simi Valley CA 93065-1812
*
* Contact: (805) 582-0582 (Tel), (805) 582-0098 (Fax)
* qjiang@tsinghua.edu
*
*/

import java.io.*;

public class ReadBuffer extends Thread
{

private SerialBuffer ComBuffer;

public ReadBuffer(SerialBuffer SB)
{
        ComBuffer = SB;
}

public void run()
{

String Msg;
while (true)
{
        Msg = ComBuffer.GetMsg();
        System.out.println(Msg);
}

}

}

/*
*
* WriteSerial.java 1.0
* Program to send a star to the serial port every 5 seconds.
*
* Created: March 27, 2001
*
* Author : Qingye Jiang (John)
* American GNC Corporation
* 888 Easy St, Simi Valley CA 93065-1812
*
* Contact: (805) 582-0582 (Tel), (805) 582-0098 (Fax)
* qjiang@tsinghua.edu
*
*/

import java.io.*;

public class WriteSerial extends Thread
{

private SerialBuffer ComBuffer;
private OutputStream ComPort;

public WriteSerial(OutputStream Port)
{
        ComPort = Port;
}

public void run()
{

int c;
try
{

while (true)
{

ComPort.write('*');
try
{
        wait(5000);
} catch (InterruptedException e) { }

}

} catch (IOException e)
{
        System.out.println(e.getMessage());
}

}

}

/*
*
* SendCom.java 1.0
*
* Project: Java Based Information Exchange Support System
* Onboard Plug-in System
* Sending data through serial port
*
* Created: March 15, 2001
*
* Author : Qingye Jiang (John)
* American GNC Corporation
* 888 Easy St, Simi Valley CA 93065-1812
*
* Contact: (805) 582-0582 (Tel), (805) 582-0098 (Fax)
*
*/

import java.io.*;

public class SendCom
{

public static void main(String[] args)
{

File OutFile = new File("SEND.TXT");
File ComPort = new File("COM2");

int c;

try
{

FileReader in = new FileReader(OutFile);
FileWriter out = new FileWriter(ComPort);
while ((c = in.read()) != -1)
        out.write(c);
in.close();
out.close();

} catch (IOException e) {}

}

}

SEND.TXT*

This is a sample of the data file for program testing. *

It should be in the same directory as the SendCom.class file.*

When you run this sample program, connect your COM1 and COM2 with a
serial cable so that you can test this program on one machine. If
you have two machines, you can connect the two machine via a serial
cable and test it. Modified the definition of ComPort in the program
if necessary. *

Thank you for testing this program. If you have any suggestions please
kindly let me know. *

小結(jié):

在上面的例程中，大多數(shù)的程序僅對(duì)我前天發(fā)的《一個(gè)使用Java讀取串口的程序》
一文做了小篇幅的改動(dòng)，有幾個(gè)程序和數(shù)據(jù)文件都沒(méi)有改動(dòng)。但是為了本文的完整
性，仍然將雷同的內(nèi)容也貼了一遍，還望斑竹多多見(jiàn)諒。

這個(gè)例程和前面一個(gè)例程的區(qū)別在于前面一個(gè)例程使用了文件IO，而本例程使用了
Comm API。在C語(yǔ)言里面用fopen()函數(shù)來(lái)打開(kāi)串口是可讀也可寫(xiě)的，但是在Java里
面聲明了File以后并不立即打開(kāi)文件，文件是在聲明FileReader或者FileWriter時(shí)
才打開(kāi)的。由于串口不能同時(shí)被打開(kāi)兩次，所以讀操作和寫(xiě)操作不能夠同時(shí)進(jìn)行，
不能夠?qū)崿F(xiàn)全雙工通訊。

Comm API雖然能夠?qū)崿F(xiàn)全雙工通訊，但是由于它不是標(biāo)準(zhǔn)的Java API，代碼的可移
植性難以保證。如果程序并不要求實(shí)現(xiàn)全雙工的話，我認(rèn)為利用文件操作不失為一
個(gè)好辦法。