jremabstractprotocol.java

JRemoteControl is a simple Java&#8482 driven bluetooth remote control.It allows you to initiate virt

/*
 * JRemCntl - Copyright (C) 2007 Filippo Di Vattimo <[e-mail]>
 * See COPYING
 */

package fildiv.jremcntl.common.proto;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public abstract class JRemAbstractProtocol {
	
	// size
	
	protected final static int LENGHT_INT = 4;
	protected final static int LENGHT_SHORT = 2;
	
	private final static int HEADER_SIZE = 
		LENGHT_INT * 2;
		
	private InputStream in;
	private OutputStream out;
	
	public JRemAbstractProtocol(InputStream in, OutputStream out) {
		this.in = in;
		this.out = out;
		
	}
	public InputStream getInputStream() {
		return in;
	}
		
	public boolean isClosed() {
		
		return in == null;
	}
	
	public void close() {
		
		if (isClosed())
			return;
		
		try {
			if (in != null) {
				
				synchronized (in) {
					in.close();
				}
				
				in = null;
			}

			if (out != null) {

				synchronized (out) {
					out.close();
				}

				out = null;
			}
			
		} catch(Exception e) {
			
		}
	}
	
	protected void createMessage(ByteWriter bw, int size, int type) {
		
		bw.setBytes(newMessageBuffer(size));
		addHeader(bw, type, size);
	}
	
	protected void addHeader(ByteWriter bw, int type, int size) {
		
		bw.addInt(size + LENGHT_INT);
		bw.addInt(type);
	}
		
	protected byte[] newMessageBuffer(int size) {
		
		int packetSize = HEADER_SIZE + size;
		
		byte []data = new byte[packetSize];
				
		return data;
	}
	
	protected ByteReader readPacket(boolean lockThread) throws IOException {

		if (!lockThread) {
			if (in.available() == 0)
				return null;
		}
			
		byte[] lengthBuf = new byte[LENGHT_INT];
		readFully(in, lengthBuf);

		ByteReader br = new ByteReader();
		br.setBytes(lengthBuf);
		int length = br.getInt();

		byte[] bytes = new byte[length];
		readFully(in, bytes);
		
		br.setBytes(bytes);

		return br;
	}
	
	protected void sendMessage(byte[] message) throws JRemDataTransferException {
		
		if (isClosed())
			throw new JRemDataTransferException(
					"Unable to send message, connection doesn't exist!");
		
		try {
			synchronized(out) {

				out.write(message);
				out.flush();
			}
			
		} catch (IOException e) {
			throw new JRemDataTransferException(e);
		}
	}

	protected void readFully(InputStream in, byte[] buffer)
			throws IOException {

		int bytesRead = 0;
		while (bytesRead < buffer.length) {
			int count = in.read(buffer, bytesRead, 
					buffer.length - bytesRead);

			if (count == -1)
				throw new IOException("Input stream closed");

			bytesRead += count;
		}
	}
}