serialbean.java

Java中串口通讯

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 57600, 8, 1, none.

			try
			{
				serialPort.setSerialPortParams(57600,
						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.
	 *
	 */

	@SuppressWarnings("deprecation")
	public void ClosePort()
	{
		RT.stop();
		serialPort.close();
	}
}