linkpacketconnection.java

来自「gps garmingpstool-src-0[1].9.tar.gz」· Java 代码 · 共 208 行

package net.aetherial.gis.garmin;

import java.io.*;
import java.util.*;
import javax.comm.*;
import net.aetherial.gis.garmin.*;

public class LinkPacketConnection
{
	public LinkPacketConnection ()
	{
		ConsoleConfig cc = new ConsoleConfig ();
		
		// Open connection to Comm Port
		
		try 
		{
			ttyS = (SerialPort) CommPortIdentifier.getPortIdentifier (cc.getSerialPort ()).open (new String ("Garmin GPS"), 100);

			ttyS.setSerialPortParams (9600, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
		}
		catch (NoSuchPortException e)
		{
			System.err.println ("The specified port does not exist.");
		}
		catch (PortInUseException e)
		{
			System.err.println ("That port is already in use.");
		}
		catch (UnsupportedCommOperationException e)
		{
			System.err.println ("That port operation is not supported on this platform.");
		}

		try
		{
			in = new BufferedInputStream (ttyS.getInputStream ());
			out = ttyS.getOutputStream ();
		}
		catch (IOException e)
		{
			System.err.println ("Error opening serial port.");
		}
		catch (NullPointerException e)
		{
			System.err.println (e);
		}

	}

	public void destroy ()
	{
		ttyS.close ();
		try
		{
			in.close ();
			out.close ();
		}
		catch (IOException e)
		{
		
		}
	}

	public void send (LinkPacket packet)
	{
		boolean acked = false;

		while (! acked)
		{
			ByteArrayOutputStream baos = new ByteArrayOutputStream ();
			byte single = (byte) 255;

			try
			{
				out.write (packet.toByteArray ());
			}
			catch (IOException e)
			{
				System.err.println (e);
			}
			catch (NullPointerException e)
			{
				System.err.println (e);
			}

// Need to implement proper DLE behavior...

			try
			{
				while (single != (byte) Garmin.EOT)
				{
					single = (byte) in.read ();
					baos.write (single);
				}
			}
			catch (IOException e)
			{
				System.err.println (e);
			}
			catch (NullPointerException e)
			{
				System.err.println (e);
			}

			LinkPacket ack = new LinkPacket (baos.toByteArray ());

			if (ack.getPacketType () == Garmin.ACK)
			{
				acked = true;
			}
		}
	}

	LinkPacket receive ()
	{
		boolean vrfyRcpt = false;
		LinkPacket rcpt = new LinkPacket (0, null);

		while (!vrfyRcpt)
		{
			byte[] header = new byte[3];
			byte[] nullByte = {0, 0};
			int payloadsize;
		
			try
			{
				while (header[0] != (byte) 16)
				{
					header[0] = (byte) in.read ();
				}
				header[1] = (byte) in.read ();
				header[2] = (byte) in.read ();

				// System.out.println ("Packet size: "+header[2]);

				if (header[2] >= 0)
					payloadsize = (int) header[2];
				else
					payloadsize = 256 - (int) header[2];

				// System.out.println ("Payload size: "+payloadsize);
			
				
				byte[] packet = new byte[payloadsize + 6];

				packet[0] = header[0];
				packet[1] = header[1];
				packet[2] = header[2];

				for (int i = 3; i < (payloadsize + 6); i++)
				{
					packet[i] = (byte) in.read ();
				
					if (packet[i] == (byte) 16)
					{
						byte b = (byte) in.read ();
						
						if (b == (byte) 3)
							break;
						else if (b != (byte) 16)
						{
							System.out.println ("DLE anomaly! b = "+b);
						}
					}
				}

				rcpt = new LinkPacket (packet);
			}
			catch (IOException e)
			{
				System.err.println (e);
			}

			nullByte[0] = (byte) rcpt.getPacketType ();

			LinkPacket ack;

		//	if (rcpt.goodChecksum ())
			if (true)
			{
				vrfyRcpt = true;
				ack = new LinkPacket (Garmin.ACK, nullByte);
			}
			else
			{
		//		rcpt.printPacket ();
				ack = new LinkPacket (Garmin.NAK, nullByte);
			}

			try
			{
				out.write (ack.toByteArray ());
			}
			catch (IOException e)
			{
				System.err.println ("Error writing to serial port.");
			}
		}

		return rcpt;
	}
		
	SerialPort ttyS;
	BufferedInputStream in;
	OutputStream out;
}