randomaccessbytestream.java

冒险岛私服Java版服务端(Odinms)源代码。学习JAVA开发的朋友

/*
	This file is part of the OdinMS Maple Story Server
    Copyright (C) 2008 Patrick Huy <[e-mail]> 
                       Matthias Butz <[e-mail]>
                       Jan Christian Meyer <[e-mail]>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License version 3
    as published by the Free Software Foundation. You may not use, modify
    or distribute this program under any other version of the
    GNU Affero General Public License.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.sf.odinms.tools.data.input;

import java.io.IOException;
import java.io.RandomAccessFile;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Provides an abstract layer to a byte stream. This layer can be accessed
 * randomly.
 * 
 * @author Frz
 * @version 1.0
 * @since Revision 323
 */
public class RandomAccessByteStream implements SeekableInputStreamBytestream {
	private RandomAccessFile raf;
	private long read = 0;
	private static Logger log = LoggerFactory
			.getLogger(RandomAccessByteStream.class);

	/**
	 * Class constructor. Wraps this object around a RandomAccessFile.
	 * 
	 * @param raf
	 *            The RandomAccessFile instance to wrap this around.
	 * @see java.io.RandomAccessFile
	 */
	public RandomAccessByteStream(RandomAccessFile raf) {
		super();
		this.raf = raf;
	}

	/**
	 * Reads a byte off of the file.
	 * 
	 * @return The byte read as an integer.
	 */
	@Override
	public int readByte() {
		int temp;
		try {
			temp = raf.read();
			if (temp == -1)
				throw new RuntimeException("EOF");
			read++;
			return temp;
		} catch (IOException e) {
			throw new RuntimeException(e);
		}
	}

	/**
	 * @see net.sf.odinms.tools.data.input.SeekableInputStreamBytestream#seek(long)
	 */
	@Override
	public void seek(long offset) throws IOException {
		raf.seek(offset);
	}

	/**
	 * @see net.sf.odinms.tools.data.input.SeekableInputStreamBytestream#getPosition()
	 */
	@Override
	public long getPosition() throws IOException {
		return raf.getFilePointer();
	}

	/**
	 * Get the number of bytes read.
	 * 
	 * @return The number of bytes read as a long integer.
	 */
	@Override
	public long getBytesRead() {
		return read;
	}

	/**
	 * Get the number of bytes available for reading.
	 * 
	 * @return The number of bytes available for reading as a long integer.
	 */
	@Override
	public long available() {
		try {
			return raf.length() - raf.getFilePointer();
		} catch (IOException e) {
			log.error("ERROR", e);
			return 0;
		}
	}
}