genericlittleendianaccessor.java.svn-base

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.ByteArrayOutputStream;

/**
 * Provides a generic interface to a Little Endian stream of bytes.
 * 
 * @version 1.0
 * @author Frz
 * @since Revision 323
 */
public class GenericLittleEndianAccessor implements LittleEndianAccessor {
	private ByteInputStream bs;

	/**
	 * Class constructor - Wraps the accessor around a stream of bytes.
	 * 
	 * @param bs The byte stream to wrap the accessor around.
	 */
	public GenericLittleEndianAccessor(ByteInputStream bs) {
		this.bs = bs;
	}

	/**
	 * Read a single byte from the stream.
	 * 
	 * @return The byte read.
	 * @see net.sf.odinms.tools.data.input.ByteInputStream#readByte
	 */
	@Override
	public byte readByte() {
		return (byte) bs.readByte();
	}

	/**
	 * Reads an integer from the stream.
	 * 
	 * @return The integer read.
	 */
	@Override
	public int readInt() {
		int byte1, byte2, byte3, byte4;

		byte1 = bs.readByte();
		byte2 = bs.readByte();
		byte3 = bs.readByte();
		byte4 = bs.readByte();
		return (byte4 << 24) + (byte3 << 16) + (byte2 << 8) + byte1;
	}

	/**
	 * Reads a short integer from the stream.
	 * 
	 * @return The short read.
	 */
	@Override
	public short readShort() {
		int byte1, byte2;
		byte1 = bs.readByte();
		byte2 = bs.readByte();
		return (short) ((byte2 << 8) + byte1);
	}

	/**
	 * Reads a single character from the stream.
	 * 
	 * @return The character read.
	 */
	@Override
	public char readChar() {
		return (char) readShort();
	}

	/**
	 * Reads a long integer from the stream.
	 * 
	 * @return The long integer read.
	 */
	@Override
	public long readLong() {
		long byte1 = bs.readByte();
		long byte2 = bs.readByte();
		long byte3 = bs.readByte();
		long byte4 = bs.readByte();
		long byte5 = bs.readByte();
		long byte6 = bs.readByte();
		long byte7 = bs.readByte();
		long byte8 = bs.readByte();

		return (byte8 << 56) + (byte7 << 48) + (byte6 << 40) + (byte5 << 32) + (byte4 << 24) + (byte3 << 16) +
			(byte2 << 8) + byte1;
	}

	/**
	 * Reads a floating point integer from the stream.
	 * 
	 * @return The float-type integer read.
	 */
	@Override
	public float readFloat() {
		return Float.intBitsToFloat(readInt());
	}

	/**
	 * Reads a double-precision integer from the stream.
	 * 
	 * @return The double-type integer read.
	 */
	@Override
	public double readDouble() {
		return Double.longBitsToDouble(readLong());
	}

	/**
	 * Reads an ASCII string from the stream with length <code>n</code>.
	 * 
	 * @param n Number of characters to read.
	 * @return The string read.
	 */
	public final String readAsciiString(int n) {
		char ret[] = new char[n];
		for (int x = 0; x < n; x++) {
			ret[x] = (char) readByte();
		}
		return String.valueOf(ret);
	}

	/**
	 * Reads a null-terminated string from the stream.
	 * 
	 * @return The string read.
	 */
	public final String readNullTerminatedAsciiString() {
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		byte b = 1;
		while (b != 0) {
			b = readByte();
			baos.write(b);
		}
		byte[] buf = baos.toByteArray();
		char[] chrBuf = new char[buf.length];
		for (int x = 0; x < buf.length; x++) {
			chrBuf[x] = (char) buf[x];
		}
		return String.valueOf(chrBuf);
	}

	/**
	 * Gets the number of bytes read from the stream so far.
	 * 
	 * @return A long integer representing the number of bytes read.
	 * @see net.sf.odinms.tools.data.input.ByteInputStream#getBytesRead()
	 */
	public long getBytesRead() {
		return bs.getBytesRead();
	}

	/**
	 * Reads a MapleStory convention lengthed ASCII string.
	 * This consists of a short integer telling the length of the string,
	 * then the string itself.
	 * 
	 * @return The string read.
	 */
	@Override
	public String readMapleAsciiString() {
		return readAsciiString(readShort());
	}

	/**
	 * Reads <code>num</code> bytes off the stream.
	 * 
	 * @param num The number of bytes to read.
	 * @return An array of bytes with the length of <code>num</code>
	 */
	@Override
	public byte[] read(int num) {
		byte[] ret = new byte[num];
		for (int x = 0; x < num; x++) {
			ret[x] = readByte();
		}
		return ret;
	}

	/**
	 * Skips the current position of the stream <code>num</code> bytes ahead.
	 * 
	 * @param num Number of bytes to skip.
	 */
	@Override
	public void skip(int num) {
		for (int x = 0; x < num; x++) {
			readByte();
		}
	}

	/**
	 * @see net.sf.odinms.tools.data.input.ByteInputStream#available
	 */
	@Override
	public long available() {
		return bs.available();
	}

	/**
	 * @see java.lang.Object#toString
	 */
	@Override
	public String toString() {
		return bs.toString();
	}
}