Apache codec中的base64

一直使用sun的base64,但是感觉不是很好,毕竟不是标准包中的.

所以把codec中的base64摘出来,以备后用

 

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.UnsupportedEncodingException;
import java.math.BigInteger;

/**
 * Provides Base64 encoding and decoding as defined by RFC 2045.
 * 
 * <p>
 * This class implements section <cite>6.8. Base64
 * Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose Internet
 * Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by
 * Freed and Borenstein.
 * </p>
 * <p>
 * The class can be parameterized in the following manner with various
 * constructors:
 * <ul>
 * <li>URL-safe mode: Default off.</li>
 * <li>Line length: Default 76. Line length that aren't multiples of 4 will
 * still essentially end up being multiples of 4 in the encoded data.
 * <li>Line separator: Default is CRLF ("\r\n")</li>
 * </ul>
 * </p>
 * <p>
 * Since this class operates directly on byte streams, and not character
 * streams, it is hard-coded to only encode/decode character encodings which are
 * compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8,
 * etc).
 * </p>
 * 
 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
 * @author Apache Software Foundation
 * @since 1.0
 * @version $Id: Base64.java 801706 2009-08-06 16:27:06Z niallp $
 */
public class Base64 {
	private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;

	private static final int DEFAULT_BUFFER_SIZE = 8192;

	/**
	 * Chunk size per RFC 2045 section 6.8.
	 * 
	 * <p>
	 * The {@value} character limit does not count the trailing CRLF, but counts
	 * all other characters, including any equal signs.
	 * </p>
	 * 
	 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section
	 *      6.8</a>
	 */
	static final int CHUNK_SIZE = 76;

	/**
	 * Chunk separator per RFC 2045 section 2.1.
	 * 
	 * <p>
	 * N.B. The next major release may break compatibility and make this field
	 * private.
	 * </p>
	 * 
	 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section
	 *      2.1</a>
	 */
	static final byte[] CHUNK_SEPARATOR = { '\r', '\n' };

	/**
	 * This array is a lookup table that translates 6-bit positive integer index
	 * values into their "Base64 Alphabet" equivalents as specified in Table 1
	 * of RFC 2045.
	 * 
	 * Thanks to "commons" project in ws.apache.org for this code.
	 * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
	 */
	private static final byte[] STANDARD_ENCODE_TABLE = { 'A', 'B', 'C', 'D',
			'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q',
			'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
			'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q',
			'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3',
			'4', '5', '6', '7', '8', '9', '+', '/' };

	/**
	 * This is a copy of the STANDARD_ENCODE_TABLE above, but with + and /
	 * changed to - and _ to make the encoded Base64 results more URL-SAFE. This
	 * table is only used when the Base64's mode is set to URL-SAFE.
	 */
	private static final byte[] URL_SAFE_ENCODE_TABLE = { 'A', 'B', 'C', 'D',
			'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q',
			'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
			'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q',
			'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3',
			'4', '5', '6', '7', '8', '9', '-', '_' };

	/**
	 * Byte used to pad output.
	 */
	private static final byte PAD = '=';

	/**
	 * This array is a lookup table that translates Unicode characters drawn
	 * from the "Base64 Alphabet" (as specified in Table 1 of RFC 2045) into
	 * their 6-bit positive integer equivalents. Characters that are not in the
	 * Base64 alphabet but fall within the bounds of the array are translated to
	 * -1.
	 * 
	 * Note: '+' and '-' both decode to 62. '/' and '_' both decode to 63. This
	 * means decoder seamlessly handles both URL_SAFE and STANDARD base64. (The
	 * encoder, on the other hand, needs to know ahead of time what to emit).
	 * 
	 * Thanks to "commons" project in ws.apache.org for this code.
	 * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
	 */
	private static final byte[] DECODE_TABLE = { -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, 62, -1, 62, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
			-1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
			12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1,
			-1, 63, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
			40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 };

	/** Mask used to extract 6 bits, used when encoding */
	private static final int MASK_6BITS = 0x3f;

	/** Mask used to extract 8 bits, used in decoding base64 bytes */
	private static final int MASK_8BITS = 0xff;

	// The static final fields above are used for the original static byte[]
	// methods on Base64.
	// The private member fields below are used with the new streaming approach,
	// which requires
	// some state be preserved between calls of encode() and decode().

	/**
	 * Encode table to use: either STANDARD or URL_SAFE. Note: the DECODE_TABLE
	 * above remains static because it is able to decode both STANDARD and
	 * URL_SAFE streams, but the encodeTable must be a member variable so we can
	 * switch between the two modes.
	 */
	private final byte[] encodeTable;

	/**
	 * Line length for encoding. Not used when decoding. A value of zero or less
	 * implies no chunking of the base64 encoded data.
	 */
	private final int lineLength;

	/**
	 * Line separator for encoding. Not used when decoding. Only used if
	 * lineLength > 0.
	 */
	private final byte[] lineSeparator;

	/**
	 * Convenience variable to help us determine when our buffer is going to run
	 * out of room and needs resizing.
	 * <code>decodeSize = 3 + lineSeparator.length;</code>
	 */
	private final int decodeSize;

	/**
	 * Convenience variable to help us determine when our buffer is going to run
	 * out of room and needs resizing.
	 * <code>encodeSize = 4 + lineSeparator.length;</code>
	 */
	private final int encodeSize;

	/**
	 * Buffer for streaming.
	 */
	private byte[] buffer;

	/**
	 * Position where next character should be written in the buffer.
	 */
	private int pos;

	/**
	 * Position where next character should be read from the buffer.
	 */
	private int readPos;

	/**
	 * Variable tracks how many characters have been written to the current
	 * line. Only used when encoding. We use it to make sure each encoded line
	 * never goes beyond lineLength (if lineLength > 0).
	 */
	private int currentLinePos;

	/**
	 * Writes to the buffer only occur after every 3 reads when encoding, an
	 * every 4 reads when decoding. This variable helps track that.
	 */
	private int modulus;

	/**
	 * Boolean flag to indicate the EOF has been reached. Once EOF has been
	 * reached, this Base64 object becomes useless, and must be thrown away.
	 */
	private boolean eof;

	/**
	 * Place holder for the 3 bytes we're dealing with for our base64 logic.
	 * Bitwise operations store and extract the base64 encoding or decoding from
	 * this variable.
	 */
	private int x;

	/**
	 * Creates a Base64 codec used for decoding (all modes) and encoding in
	 * URL-unsafe mode.
	 * <p>
	 * When encoding the line length is 76, the line separator is CRLF, and the
	 * encoding table is STANDARD_ENCODE_TABLE.
	 * </p>
	 * 
	 * <p>
	 * When decoding all variants are supported.
	 * </p>
	 */
	public Base64() {
		this(false);
	}

	/**
	 * Creates a Base64 codec used for decoding (all modes) and encoding in the
	 * given URL-safe mode.
	 * <p>
	 * When encoding the line length is 76, the line separator is CRLF, and the
	 * encoding table is STANDARD_ENCODE_TABLE.
	 * </p>
	 * 
	 * <p>
	 * When decoding all variants are supported.
	 * </p>
	 * 
	 * @param urlSafe
	 *            if <code>true</code>, URL-safe encoding is used. In most cases
	 *            this should be set to <code>false</code>.
	 * @since 1.4
	 */
	public Base64(boolean urlSafe) {
		this(CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe);
	}

	/**
	 * Creates a Base64 codec used for decoding (all modes) and encoding in
	 * URL-unsafe mode.
	 * <p>
	 * When encoding the line length is given in the constructor, the line
	 * separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
	 * </p>
	 * <p>
	 * Line lengths that aren't multiples of 4 will still essentially end up
	 * being multiples of 4 in the encoded data.
	 * </p>
	 * <p>
	 * When decoding all variants are supported.
	 * </p>
	 * 
	 * @param lineLength
	 *            Each line of encoded data will be at most of the given length
	 *            (rounded down to nearest multiple of 4). If lineLength <= 0,
	 *            then the output will not be divided into lines (chunks).
	 *            Ignored when decoding.
	 * @since 1.4
	 */
	public Base64(int lineLength) {
		this(lineLength, CHUNK_SEPARATOR);
	}

	/**
	 * Creates a Base64 codec used for decoding (all modes) and encoding in
	 * URL-unsafe mode.
	 * <p>
	 * When encoding the line length and line separator are given in the
	 * constructor, and the encoding table is STANDARD_ENCODE_TABLE.
	 * </p>
	 * <p>
	 * Line lengths that aren't multiples of 4 will still essentially end up
	 * being multiples of 4 in the encoded data.
	 * </p>
	 * <p>
	 * When decoding all variants are supported.
	 * </p>
	 * 
	 * @param lineLength
	 *            Each line of encoded data will be at most of the given length
	 *            (rounded down to nearest multiple of 4). If lineLength <= 0,
	 *            then the output will not be divided into lines (chunks).
	 *            Ignored when decoding.
	 * @param lineSeparator
	 *            Each line of encoded data will end with this sequence of
	 *            bytes.
	 * @throws IllegalArgumentException
	 *             Thrown when the provided lineSeparator included some base64
	 *             characters.
	 * @since 1.4
	 */
	public Base64(int lineLength, byte[] lineSeparator) {
		this(lineLength, lineSeparator, false);
	}

	/**
	 * Creates a Base64 codec used for decoding (all modes) and encoding in
	 * URL-unsafe mode.
	 * <p>
	 * When encoding the line length and line separator are given in the
	 * constructor, and the encoding table is STANDARD_ENCODE_TABLE.
	 * </p>
	 * <p>
	 * Line lengths that aren't multiples of 4 will still essentially end up
	 * being multiples of 4 in the encoded data.
	 * </p>
	 * <p>
	 * When decoding all variants are supported.
	 * </p>
	 * 
	 * @param lineLength
	 *            Each line of encoded data will be at most of the given length
	 *            (rounded down to nearest multiple of 4). If lineLength <= 0,
	 *            then the output will not be divided into lines (chunks).
	 *            Ignored when decoding.
	 * @param lineSeparator
	 *            Each line of encoded data will end with this sequence of
	 *            bytes.
	 * @param urlSafe
	 *            Instead of emitting '+' and '/' we emit '-' and '_'
	 *            respectively. urlSafe is only applied to encode operations.
	 *            Decoding seamlessly handles both modes.
	 * @throws IllegalArgumentException
	 *             The provided lineSeparator included some base64 characters.
	 *             That's not going to work!
	 * @since 1.4
	 */
	public Base64(int lineLength, byte[] lineSeparator, boolean urlSafe) {
		if (lineSeparator == null) {
			lineLength = 0; // disable chunk-separating
			lineSeparator = CHUNK_SEPARATOR; // this just gets ignored
		}
		this.lineLength = lineLength > 0 ? lineLength / 4 * 4 : 0;
		this.lineSeparator = new byte[lineSeparator.length];
		System.arraycopy(lineSeparator, 0, this.lineSeparator, 0,
				lineSeparator.length);
		if (lineLength > 0) {
			encodeSize = 4 + lineSeparator.length;
		} else {
			encodeSize = 4;
		}
		decodeSize = encodeSize - 1;
		if (containsBase64Byte(lineSeparator)) {
			String sep = newStringUtf8(lineSeparator);
			throw new IllegalArgumentException(
					"lineSeperator must not contain base64 characters: [" + sep
							+ "]");
		}
		encodeTable = urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
	}

	private static String newStringUtf8(byte[] chars) {
		if (chars == null) {
			return null;
		}
		try {
			return new String(chars, "UTF-8");
		} catch (UnsupportedEncodingException e) {
			return null;
		}
	}

	/**
	 * Returns our current encode mode. True if we're URL-SAFE, false otherwise.
	 * 
	 * @return true if we're in URL-SAFE mode, false otherwise.
	 * @since 1.4
	 */
	public boolean isUrlSafe() {
		return encodeTable == URL_SAFE_ENCODE_TABLE;
	}

	/**
	 * Returns true if this Base64 object has buffered data for reading.
	 * 
	 * @return true if there is Base64 object still available for reading.
	 */
	boolean hasData() {
		return buffer != null;
	}

	/**
	 * Returns the amount of buffered data available for reading.
	 * 
	 * @return The amount of buffered data available for reading.
	 */
	int avail() {
		return buffer != null ? pos - readPos : 0;
	}

	/** Doubles our buffer. */
	private void resizeBuffer() {
		if (buffer == null) {
			buffer = new byte[DEFAULT_BUFFER_SIZE];
			pos = 0;
			readPos = 0;
		} else {
			byte[] b = new byte[buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
			System.arraycopy(buffer, 0, b, 0, buffer.length);
			buffer = b;
		}
	}

	/**
	 * Extracts buffered data into the provided byte[] array, starting at
	 * position bPos, up to a maximum of bAvail bytes. Returns how many bytes
	 * were actually extracted.
	 * 
	 * @param b
	 *            byte[] array to extract the buffered data into.
	 * @param bPos
	 *            position in byte[] array to start extraction at.
	 * @param bAvail
	 *            amount of bytes we're allowed to extract. We may extract fewer
	 *            (if fewer are available).
	 * @return The number of bytes successfully extracted into the provided
	 *         byte[] array.
	 */
	int readResults(byte[] b, int bPos, int bAvail) {
		if (buffer != null) {
			int len = Math.min(avail(), bAvail);
			if (buffer != b) {
				System.arraycopy(buffer, readPos, b, bPos, len);
				readPos += len;
				if (readPos >= pos) {
					buffer = null;
				}
			} else {
				// Re-using the original consumer's output array is only
				// allowed for one round.
				buffer = null;
			}
			return len;
		}
		return eof ? -1 : 0;
	}

	/**
	 * Sets the streaming buffer. This is a small optimization where we try to
	 * buffer directly to the consumer's output array for one round (if the
	 * consumer calls this method first) instead of starting our own buffer.
	 * 
	 * @param out
	 *            byte[] array to buffer directly to.
	 * @param outPos
	 *            Position to start buffering into.
	 * @param outAvail
	 *            Amount of bytes available for direct buffering.
	 */
	void setInitialBuffer(byte[] out, int outPos, int outAvail) {
		// We can re-use consumer's original output array under
		// special circumstances, saving on some System.arraycopy().
		if (out != null && out.length == outAvail) {
			buffer = out;
			pos = outPos;
			readPos = outPos;
		}
	}

	/**
	 * <p>
	 * Encodes all of the provided data, starting at inPos, for inAvail bytes.
	 * Must be called at least twice: once with the data to encode, and once
	 * with inAvail set to "-1" to alert encoder that EOF has been reached, so
	 * flush last remaining bytes (if not multiple of 3).
	 * </p>
	 * <p>
	 * Thanks to "commons" project in ws.apache.org for the bitwise operations,
	 * and general approach.
	 * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
	 * </p>
	 * 
	 * @param in
	 *            byte[] array of binary data to base64 encode.
	 * @param inPos
	 *            Position to start reading data from.
	 * @param inAvail
	 *            Amount of bytes available from input for encoding.
	 */
	void encode(byte[] in, int inPos, int inAvail) {
		if (eof) {
			return;
		}
		// inAvail < 0 is how we're informed of EOF in the underlying data we're
		// encoding.
		if (inAvail < 0) {
			eof = true;
			if (buffer == null || buffer.length - pos < encodeSize) {
				resizeBuffer();
			}
			switch (modulus) {
			case 1:
				buffer[pos++] = encodeTable[x >> 2 & MASK_6BITS];
				buffer[pos++] = encodeTable[x << 4 & MASK_6BITS];
				// URL-SAFE skips the padding to further reduce size.
				if (encodeTable == STANDARD_ENCODE_TABLE) {
					buffer[pos++] = PAD;
					buffer[pos++] = PAD;
				}
				break;

			case 2:
				buffer[pos++] = encodeTable[x >> 10 & MASK_6BITS];
				buffer[pos++] = encodeTable[x >> 4 & MASK_6BITS];
				buffer[pos++] = encodeTable[x << 2 & MASK_6BITS];
				// URL-SAFE skips the padding to further reduce size.
				if (encodeTable == STANDARD_ENCODE_TABLE) {
					buffer[pos++] = PAD;
				}
				break;
			}
			if (lineLength > 0 && pos > 0) {
				System.arraycopy(lineSeparator, 0, buffer, pos,
						lineSeparator.length);
				pos += lineSeparator.length;
			}
		} else {
			for (int i = 0; i < inAvail; i++) {
				if (buffer == null || buffer.length - pos < encodeSize) {
					resizeBuffer();
				}
				modulus = ++modulus % 3;
				int b = in[inPos++];
				if (b < 0) {
					b += 256;
				}
				x = (x << 8) + b;
				if (0 == modulus) {
					buffer[pos++] = encodeTable[x >> 18 & MASK_6BITS];
					buffer[pos++] = encodeTable[x >> 12 & MASK_6BITS];
					buffer[pos++] = encodeTable[x >> 6 & MASK_6BITS];
					buffer[pos++] = encodeTable[x & MASK_6BITS];
					currentLinePos += 4;
					if (lineLength > 0 && lineLength <= currentLinePos) {
						System.arraycopy(lineSeparator, 0, buffer, pos,
								lineSeparator.length);
						pos += lineSeparator.length;
						currentLinePos = 0;
					}
				}
			}
		}
	}

	/**
	 * <p>
	 * Decodes all of the provided data, starting at inPos, for inAvail bytes.
	 * Should be called at least twice: once with the data to decode, and once
	 * with inAvail set to "-1" to alert decoder that EOF has been reached. The
	 * "-1" call is not necessary when decoding, but it doesn't hurt, either.
	 * </p>
	 * <p>
	 * Ignores all non-base64 characters. This is how chunked (e.g. 76
	 * character) data is handled, since CR and LF are silently ignored, but has
	 * implications for other bytes, too. This method subscribes to the
	 * garbage-in, garbage-out philosophy: it will not check the provided data
	 * for validity.
	 * </p>
	 * <p>
	 * Thanks to "commons" project in ws.apache.org for the bitwise operations,
	 * and general approach.
	 * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
	 * </p>
	 * 
	 * @param in
	 *            byte[] array of ascii data to base64 decode.
	 * @param inPos
	 *            Position to start reading data from.
	 * @param inAvail
	 *            Amount of bytes available from input for encoding.
	 */
	void decode(byte[] in, int inPos, int inAvail) {
		if (eof) {
			return;
		}
		if (inAvail < 0) {
			eof = true;
		}
		for (int i = 0; i < inAvail; i++) {
			if (buffer == null || buffer.length - pos < decodeSize) {
				resizeBuffer();
			}
			byte b = in[inPos++];
			if (b == PAD) {
				// We're done.
				eof = true;
				break;
			} else {
				if (b >= 0 && b < DECODE_TABLE.length) {
					int result = DECODE_TABLE[b];
					if (result >= 0) {
						modulus = ++modulus % 4;
						x = (x << 6) + result;
						if (modulus == 0) {
							buffer[pos++] = (byte) (x >> 16 & MASK_8BITS);
							buffer[pos++] = (byte) (x >> 8 & MASK_8BITS);
							buffer[pos++] = (byte) (x & MASK_8BITS);
						}
					}
				}
			}
		}

		// Two forms of EOF as far as base64 decoder is concerned: actual
		// EOF (-1) and first time '=' character is encountered in stream.
		// This approach makes the '=' padding characters completely optional.
		if (eof && modulus != 0) {
			x = x << 6;
			switch (modulus) {
			case 2:
				x = x << 6;
				buffer[pos++] = (byte) (x >> 16 & MASK_8BITS);
				break;
			case 3:
				buffer[pos++] = (byte) (x >> 16 & MASK_8BITS);
				buffer[pos++] = (byte) (x >> 8 & MASK_8BITS);
				break;
			}
		}
	}

	/**
	 * Returns whether or not the <code>octet</code> is in the base 64 alphabet.
	 * 
	 * @param octet
	 *            The value to test
	 * @return <code>true</code> if the value is defined in the the base 64
	 *         alphabet, <code>false</code> otherwise.
	 * @since 1.4
	 */
	public static boolean isBase64(byte octet) {
		return octet == PAD || octet >= 0 && octet < DECODE_TABLE.length
				&& DECODE_TABLE[octet] != -1;
	}

	/**
	 * Tests a given byte array to see if it contains only valid characters
	 * within the Base64 alphabet. Currently the method treats whitespace as
	 * valid.
	 * 
	 * @param arrayOctet
	 *            byte array to test
	 * @return <code>true</code> if all bytes are valid characters in the Base64
	 *         alphabet or if the byte array is empty; false, otherwise
	 */
	public static boolean isArrayByteBase64(byte[] arrayOctet) {
		for (int i = 0; i < arrayOctet.length; i++) {
			if (!isBase64(arrayOctet[i]) && !isWhiteSpace(arrayOctet[i])) {
				return false;
			}
		}
		return true;
	}

	/**
	 * Tests a given byte array to see if it contains only valid characters
	 * within the Base64 alphabet.
	 * 
	 * @param arrayOctet
	 *            byte array to test
	 * @return <code>true</code> if any byte is a valid character in the Base64
	 *         alphabet; false herwise
	 */
	private static boolean containsBase64Byte(byte[] arrayOctet) {
		for (int i = 0; i < arrayOctet.length; i++) {
			if (isBase64(arrayOctet[i])) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Encodes binary data using the base64 algorithm but does not chunk the
	 * output.
	 * 
	 * @param binaryData
	 *            binary data to encode
	 * @return byte[] containing Base64 characters in their UTF-8
	 *         representation.
	 */
	public static byte[] encodeBase64(byte[] binaryData) {
		return encodeBase64(binaryData, false);
	}

	/**
	 * Encodes binary data using the base64 algorithm into 76 character blocks
	 * separated by CRLF.
	 * 
	 * @param binaryData
	 *            binary data to encode
	 * @return String containing Base64 characters.
	 * @since 1.4
	 */
	public static String encodeBase64String(byte[] binaryData) {
		return newStringUtf8(encodeBase64(binaryData, true));
	}

	/**
	 * Encodes binary data using a URL-safe variation of the base64 algorithm
	 * but does not chunk the output. The url-safe variation emits - and _
	 * instead of + and / characters.
	 * 
	 * @param binaryData
	 *            binary data to encode
	 * @return byte[] containing Base64 characters in their UTF-8
	 *         representation.
	 * @since 1.4
	 */
	public static byte[] encodeBase64URLSafe(byte[] binaryData) {
		return encodeBase64(binaryData, false, true);
	}

	/**
	 * Encodes binary data using a URL-safe variation of the base64 algorithm
	 * but does not chunk the output. The url-safe variation emits - and _
	 * instead of + and / characters.
	 * 
	 * @param binaryData
	 *            binary data to encode
	 * @return String containing Base64 characters
	 * @since 1.4
	 */
	public static String encodeBase64URLSafeString(byte[] binaryData) {
		return newStringUtf8(encodeBase64(binaryData, false, true));
	}

	/**
	 * Encodes binary data using the base64 algorithm and chunks the encoded
	 * output into 76 character blocks
	 * 
	 * @param binaryData
	 *            binary data to encode
	 * @return Base64 characters chunked in 76 character blocks
	 */
	public static byte[] encodeBase64Chunked(byte[] binaryData) {
		return encodeBase64(binaryData, true);
	}

	/**
	 * Decodes an Object using the base64 algorithm. This method is provided in
	 * order to satisfy the requirements of the Decoder interface, and will
	 * throw a DecoderException if the supplied object is not of type byte[] or
	 * String.
	 * 
	 * @param pObject
	 *            Object to decode
	 * @return An object (of type byte[]) containing the binary data which
	 *         corresponds to the byte[] or String supplied.
	 * @throws IllegalArgumentException
	 *             if the parameter supplied is not of type byte[]
	 */
	public Object decode(Object pObject) throws IllegalArgumentException {
		if (pObject instanceof byte[]) {
			return decode((byte[]) pObject);
		} else if (pObject instanceof String) {
			return decode((String) pObject);
		} else {
			throw new IllegalArgumentException(
					"Parameter supplied to Base64 decode is not a byte[] or a String");
		}
	}

	/**
	 * Decodes a String containing containing characters in the Base64 alphabet.
	 * 
	 * @param pArray
	 *            A String containing Base64 character data
	 * @return a byte array containing binary data
	 * @since 1.4
	 */
	public byte[] decode(String pArray) {
		return decode(getBytesUtf8(pArray));
	}

	private byte[] getBytesUtf8(String text) {
		if (text == null) {
			return null;
		}
		try {
			return text.getBytes("UTF-8");
		} catch (UnsupportedEncodingException e) {
			return null;
		}
	}

	/**
	 * Decodes a byte[] containing containing characters in the Base64 alphabet.
	 * 
	 * @param pArray
	 *            A byte array containing Base64 character data
	 * @return a byte array containing binary data
	 */
	public byte[] decode(byte[] pArray) {
		reset();
		if (pArray == null || pArray.length == 0) {
			return pArray;
		}
		long len = pArray.length * 3 / 4;
		byte[] buf = new byte[(int) len];
		setInitialBuffer(buf, 0, buf.length);
		decode(pArray, 0, pArray.length);
		decode(pArray, 0, -1); // Notify decoder of EOF.

		// Would be nice to just return buf (like we sometimes do in the encode
		// logic), but we have no idea what the line-length was (could even be
		// variable). So we cannot determine ahead of time exactly how big an
		// array is necessary. Hence the need to construct a 2nd byte array to
		// hold the final result:

		byte[] result = new byte[pos];
		readResults(result, 0, result.length);
		return result;
	}

	/**
	 * Encodes binary data using the base64 algorithm, optionally chunking the
	 * output into 76 character blocks.
	 * 
	 * @param binaryData
	 *            Array containing binary data to encode.
	 * @param isChunked
	 *            if <code>true</code> this encoder will chunk the base64 output
	 *            into 76 character blocks
	 * @return Base64-encoded data.
	 * @throws IllegalArgumentException
	 *             Thrown when the input array needs an output array bigger than
	 *             {@link Integer#MAX_VALUE}
	 */
	public static byte[] encodeBase64(byte[] binaryData, boolean isChunked) {
		return encodeBase64(binaryData, isChunked, false);
	}

	/**
	 * Encodes binary data using the base64 algorithm, optionally chunking the
	 * output into 76 character blocks.
	 * 
	 * @param binaryData
	 *            Array containing binary data to encode.
	 * @param isChunked
	 *            if <code>true</code> this encoder will chunk the base64 output
	 *            into 76 character blocks
	 * @param urlSafe
	 *            if <code>true</code> this encoder will emit - and _ instead of
	 *            the usual + and / characters.
	 * @return Base64-encoded data.
	 * @throws IllegalArgumentException
	 *             Thrown when the input array needs an output array bigger than
	 *             {@link Integer#MAX_VALUE}
	 * @since 1.4
	 */
	public static byte[] encodeBase64(byte[] binaryData, boolean isChunked,
			boolean urlSafe) {
		return encodeBase64(binaryData, isChunked, urlSafe, Integer.MAX_VALUE);
	}

	/**
	 * Encodes binary data using the base64 algorithm, optionally chunking the
	 * output into 76 character blocks.
	 * 
	 * @param binaryData
	 *            Array containing binary data to encode.
	 * @param isChunked
	 *            if <code>true</code> this encoder will chunk the base64 output
	 *            into 76 character blocks
	 * @param urlSafe
	 *            if <code>true</code> this encoder will emit - and _ instead of
	 *            the usual + and / characters.
	 * @param maxResultSize
	 *            The maximum result size to accept.
	 * @return Base64-encoded data.
	 * @throws IllegalArgumentException
	 *             Thrown when the input array needs an output array bigger than
	 *             maxResultSize
	 * @since 1.4
	 */
	public static byte[] encodeBase64(byte[] binaryData, boolean isChunked,
			boolean urlSafe, int maxResultSize) {
		if (binaryData == null || binaryData.length == 0) {
			return binaryData;
		}

		long len = getEncodeLength(binaryData, CHUNK_SIZE, CHUNK_SEPARATOR);
		if (len > maxResultSize) {
			throw new IllegalArgumentException(
					"Input array too big, the output array would be bigger ("
							+ len + ") than the specified maxium size of "
							+ maxResultSize);
		}

		Base64 b64 = isChunked ? new Base64(urlSafe) : new Base64(0,
				CHUNK_SEPARATOR, urlSafe);
		return b64.encode(binaryData);
	}

	/**
	 * Decodes a Base64 String into octets
	 * 
	 * @param base64String
	 *            String containing Base64 data
	 * @return Array containing decoded data.
	 * @since 1.4
	 */
	public static byte[] decodeBase64(String base64String) {
		return new Base64().decode(base64String);
	}

	/**
	 * Decodes Base64 data into octets
	 * 
	 * @param base64Data
	 *            Byte array containing Base64 data
	 * @return Array containing decoded data.
	 */
	public static byte[] decodeBase64(byte[] base64Data) {
		return new Base64().decode(base64Data);
	}

	/**
	 * Discards any whitespace from a base-64 encoded block.
	 * 
	 * @param data
	 *            The base-64 encoded data to discard the whitespace from.
	 * @return The data, less whitespace (see RFC 2045).
	 * @deprecated This method is no longer needed
	 */
	@Deprecated
	static byte[] discardWhitespace(byte[] data) {
		byte groomedData[] = new byte[data.length];
		int bytesCopied = 0;
		for (int i = 0; i < data.length; i++) {
			switch (data[i]) {
			case ' ':
			case '\n':
			case '\r':
			case '\t':
				break;
			default:
				groomedData[bytesCopied++] = data[i];
			}
		}
		byte packedData[] = new byte[bytesCopied];
		System.arraycopy(groomedData, 0, packedData, 0, bytesCopied);
		return packedData;
	}

	/**
	 * Checks if a byte value is whitespace or not.
	 * 
	 * @param byteToCheck
	 *            the byte to check
	 * @return true if byte is whitespace, false otherwise
	 */
	private static boolean isWhiteSpace(byte byteToCheck) {
		switch (byteToCheck) {
		case ' ':
		case '\n':
		case '\r':
		case '\t':
			return true;
		default:
			return false;
		}
	}

	// Implementation of the Encoder Interface

	/**
	 * Encodes an Object using the base64 algorithm. This method is provided in
	 * order to satisfy the requirements of the Encoder interface, and will
	 * throw an EncoderException if the supplied object is not of type byte[].
	 * 
	 * @param pObject
	 *            Object to encode
	 * @return An object (of type byte[]) containing the base64 encoded data
	 *         which corresponds to the byte[] supplied.
	 * @throws IllegalArgumentException
	 *             if the parameter supplied is not of type byte[]
	 */
	public Object encode(Object pObject) throws IllegalArgumentException {
		if (!(pObject instanceof byte[])) {
			throw new IllegalArgumentException(
					"Parameter supplied to Base64 encode is not a byte[]");
		}
		return encode((byte[]) pObject);
	}

	/**
	 * Encodes a byte[] containing binary data, into a String containing
	 * characters in the Base64 alphabet.
	 * 
	 * @param pArray
	 *            a byte array containing binary data
	 * @return A String containing only Base64 character data
	 * @since 1.4
	 */
	public String encodeToString(byte[] pArray) {
		return newStringUtf8(encode(pArray));
	}

	/**
	 * Encodes a byte[] containing binary data, into a byte[] containing
	 * characters in the Base64 alphabet.
	 * 
	 * @param pArray
	 *            a byte array containing binary data
	 * @return A byte array containing only Base64 character data
	 */
	public byte[] encode(byte[] pArray) {
		reset();
		if (pArray == null || pArray.length == 0) {
			return pArray;
		}
		long len = getEncodeLength(pArray, lineLength, lineSeparator);
		byte[] buf = new byte[(int) len];
		setInitialBuffer(buf, 0, buf.length);
		encode(pArray, 0, pArray.length);
		encode(pArray, 0, -1); // Notify encoder of EOF.
		// Encoder might have resized, even though it was unnecessary.
		if (buffer != buf) {
			readResults(buf, 0, buf.length);
		}
		// In URL-SAFE mode we skip the padding characters, so sometimes our
		// final length is a bit smaller.
		if (isUrlSafe() && pos < buf.length) {
			byte[] smallerBuf = new byte[pos];
			System.arraycopy(buf, 0, smallerBuf, 0, pos);
			buf = smallerBuf;
		}
		return buf;
	}

	/**
	 * Pre-calculates the amount of space needed to base64-encode the supplied
	 * array.
	 * 
	 * @param pArray
	 *            byte[] array which will later be encoded
	 * @param chunkSize
	 *            line-length of the output (<= 0 means no chunking) between
	 *            each chunkSeparator (e.g. CRLF).
	 * @param chunkSeparator
	 *            the sequence of bytes used to separate chunks of output (e.g.
	 *            CRLF).
	 * 
	 * @return amount of space needed to encoded the supplied array. Returns a
	 *         long since a max-len array will require Integer.MAX_VALUE + 33%.
	 */
	private static long getEncodeLength(byte[] pArray, int chunkSize,
			byte[] chunkSeparator) {
		// base64 always encodes to multiples of 4.
		chunkSize = chunkSize / 4 * 4;

		long len = pArray.length * 4 / 3;
		long mod = len % 4;
		if (mod != 0) {
			len += 4 - mod;
		}
		if (chunkSize > 0) {
			boolean lenChunksPerfectly = len % chunkSize == 0;
			len += len / chunkSize * chunkSeparator.length;
			if (!lenChunksPerfectly) {
				len += chunkSeparator.length;
			}
		}
		return len;
	}

	// Implementation of integer encoding used for crypto
	/**
	 * Decodes a byte64-encoded integer according to crypto standards such as
	 * W3C's XML-Signature
	 * 
	 * @param pArray
	 *            a byte array containing base64 character data
	 * @return A BigInteger
	 * @since 1.4
	 */
	public static BigInteger decodeInteger(byte[] pArray) {
		return new BigInteger(1, decodeBase64(pArray));
	}

	/**
	 * Encodes to a byte64-encoded integer according to crypto standards such as
	 * W3C's XML-Signature
	 * 
	 * @param bigInt
	 *            a BigInteger
	 * @return A byte array containing base64 character data
	 * @throws NullPointerException
	 *             if null is passed in
	 * @since 1.4
	 */
	public static byte[] encodeInteger(BigInteger bigInt) {
		if (bigInt == null) {
			throw new NullPointerException(
					"encodeInteger called with null parameter");
		}
		return encodeBase64(toIntegerBytes(bigInt), false);
	}

	/**
	 * Returns a byte-array representation of a <code>BigInteger</code> without
	 * sign bit.
	 * 
	 * @param bigInt
	 *            <code>BigInteger</code> to be converted
	 * @return a byte array representation of the BigInteger parameter
	 */
	static byte[] toIntegerBytes(BigInteger bigInt) {
		int bitlen = bigInt.bitLength();
		// round bitlen
		bitlen = bitlen + 7 >> 3 << 3;
		byte[] bigBytes = bigInt.toByteArray();

		if (bigInt.bitLength() % 8 != 0
				&& bigInt.bitLength() / 8 + 1 == bitlen / 8) {
			return bigBytes;
		}
		// set up params for copying everything but sign bit
		int startSrc = 0;
		int len = bigBytes.length;

		// if bigInt is exactly byte-aligned, just skip signbit in copy
		if (bigInt.bitLength() % 8 == 0) {
			startSrc = 1;
			len--;
		}
		int startDst = bitlen / 8 - len; // to pad w/ nulls as per spec
		byte[] resizedBytes = new byte[bitlen / 8];
		System.arraycopy(bigBytes, startSrc, resizedBytes, startDst, len);
		return resizedBytes;
	}

	/**
	 * Resets this Base64 object to its initial newly constructed state.
	 */
	private void reset() {
		buffer = null;
		pos = 0;
		readPos = 0;
		currentLinePos = 0;
		modulus = 0;
		eof = false;
	}

}