依据 《利用Java实现串口全双工通讯》蒋清野 更新。

更新1：修正其源代码返回的字符数比发送的字符数滞后的BUG

更新2：修正javax.comm的BUG。此BUG表现为 java BlackBox 总是返回 No serial ports found！

注：更新处标注 update by LZA

环境：Win7  + JDK1.7 + Java Communications API 2.0 (comm.jar)

ReadSerial.java

//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) {

}

}

}

SerialBean.java

//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 startss a

* thread which consistently monitors the serial port. Any signal capturred

* 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 incomin

* 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();

}

}

SerialBuffer.java

//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 incomin

* 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()) // update by LZA

{

available = true;

}

notifyAll();

}

}

SerialExample.java

import java.io.*;

import java.util.*;

import javax.comm.*;

import com.sun.comm.*;

class SerialExample {

public static void main(String[] args) {

// update by LZA

Win32Driver w32Driver = new Win32Driver();

// 这两行修正javax.comm的BUG

w32Driver.initialize();

// 这才正常初始化，才会正常找出所有port

// 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();

}

}