android: Add a Java utility class similar to bio_writer_t

2013-07-08 18:49:27 +02:00
parent 28c268d707
commit 2d378d8a74
1 changed files with 172 additions and 0 deletions
@@ -0,0 +1,172 @@
 /*
 * Copyright (C) 2013 Tobias Brunner
 * Hochschule fuer Technik Rapperswil
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * 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 General Public License
 * for more details.
 */
 package org.strongswan.android.utils;
 import java.nio.ByteBuffer;
 /**
 * Very similar to ByteBuffer (although with a stripped interface) but it
 * automatically resizes the underlying buffer.
 */
 public class BufferedByteWriter
 {
 	/**
 	 * The underlying byte buffer
 	 */
 	private byte[] mBuffer;
 	/**
 	 * ByteBuffer used as wrapper around the buffer to easily convert values
 	 */
 	private ByteBuffer mWriter;
 	/**
 	 * Create a writer with a default initial capacity
 	 */
 	public BufferedByteWriter()
 	{
 		this(0);
 	}
 	/**
 	 * Create a writer with the given initial capacity (helps avoid expensive
 	 * resizing if known).
 	 * @param capacity initial capacity
 	 */
 	public BufferedByteWriter(int capacity)
 	{
 		capacity = capacity > 4 ? capacity : 32;
 		mBuffer = new byte[capacity];
 		mWriter = ByteBuffer.wrap(mBuffer);
 	}
 	/**
 	 * Ensure that there is enough space available to write the requested
 	 * number of bytes. If necessary the internal buffer is resized.
 	 * @param required required number of bytes
 	 */
 	private void ensureCapacity(int required)
 	{
 		if (mWriter.remaining() >= required)
 		{
 			return;
 		}
 		byte[] buffer = new byte[(mBuffer.length + required) * 2];
 		System.arraycopy(mBuffer, 0, buffer, 0, mWriter.position());
 		mBuffer = buffer;
 		ByteBuffer writer = ByteBuffer.wrap(buffer);
 		writer.position(mWriter.position());
 		mWriter = writer;
 	}
 	/**
 	 * Write the given byte array to the buffer
 	 * @param value
 	 * @return the writer
 	 */
 	public BufferedByteWriter put(byte[] value)
 	{
 		ensureCapacity(value.length);
 		mWriter.put(value);
 		return this;
 	}
 	/**
 	 * Write the given byte to the buffer
 	 * @param value
 	 * @return the writer
 	 */
 	public BufferedByteWriter put(byte value)
 	{
 		ensureCapacity(1);
 		mWriter.put(value);
 		return this;
 	}
 	/**
 	 * Write the 8-bit length of the given data followed by the data itself
 	 * @param value
 	 * @return the writer
 	 */
 	public BufferedByteWriter putLen8(byte[] value)
 	{
 		ensureCapacity(1 + value.length);
 		mWriter.put((byte)value.length);
 		mWriter.put(value);
 		return this;
 	}
 	/**
 	 * Write the 16-bit length of the given data followed by the data itself
 	 * @param value
 	 * @return the writer
 	 */
 	public BufferedByteWriter putLen16(byte[] value)
 	{
 		ensureCapacity(2 + value.length);
 		mWriter.putShort((short)value.length);
 		mWriter.put(value);
 		return this;
 	}
 	/**
 	 * Write the given short value (16-bit) in big-endian order to the buffer
 	 * @param value
 	 * @return the writer
 	 */
 	public BufferedByteWriter put16(short value)
 	{
 		ensureCapacity(2);
 		mWriter.putShort(value);
 		return this;
 	}
 	/**
 	 * Write the given int value (32-bit) in big-endian order to the buffer
 	 * @param value
 	 * @return the writer
 	 */
 	public BufferedByteWriter put32(int value)
 	{
 		ensureCapacity(4);
 		mWriter.putInt(value);
 		return this;
 	}
 	/**
 	 * Write the given long value (64-bit) in big-endian order to the buffer
 	 * @param value
 	 * @return the writer
 	 */
 	public BufferedByteWriter put64(long value)
 	{
 		ensureCapacity(8);
 		mWriter.putLong(value);
 		return this;
 	}
 	/**
 	 * Convert the internal buffer to a new byte array.
 	 * @return byte array
 	 */
 	public byte[] toByteArray()
 	{
 		int length = mWriter.position();
 		byte[] bytes = new byte[length];
 		System.arraycopy(mBuffer, 0, bytes, 0, length);
 		return bytes;
 	}
 }