Java tutorial
//Copyright (c) 2006, Adobe Systems Incorporated //All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are met: // 1. Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // 2. Redistributions in binary form must reproduce the above copyright // notice, this list of conditions and the following disclaimer in the // documentation and/or other materials provided with the distribution. // 3. All advertising materials mentioning features or use of this software // must display the following acknowledgement: // This product includes software developed by the Adobe Systems Incorporated. // 4. Neither the name of the Adobe Systems Incorporated nor the // names of its contributors may be used to endorse or promote products // derived from this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY ADOBE SYSTEMS INCORPORATED ''AS IS'' AND ANY // EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE // DISCLAIMED. IN NO EVENT SHALL ADOBE SYSTEMS INCORPORATED BE LIABLE FOR ANY // DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES // (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; // LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND // ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // // http://www.adobe.com/devnet/xmp/library/eula-xmp-library-java.html package com.itextpdf.xmp.impl; /** * A utility class to perform base64 encoding and decoding as specified * in RFC-1521. See also RFC 1421. * * @version $Revision: 1.4 $ */ public class Base64 { /** marker for invalid bytes */ private static final byte INVALID = -1; /** marker for accepted whitespace bytes */ private static final byte WHITESPACE = -2; /** marker for an equal symbol */ private static final byte EQUAL = -3; /** */ private static byte[] base64 = { (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', // 0 to 3 (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H', // 4 to 7 (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', // 8 to 11 (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P', // 11 to 15 (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', // 16 to 19 (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', // 20 to 23 (byte) 'Y', (byte) 'Z', (byte) 'a', (byte) 'b', // 24 to 27 (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f', // 28 to 31 (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', // 32 to 35 (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n', // 36 to 39 (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', // 40 to 43 (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', // 44 to 47 (byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z', // 48 to 51 (byte) '0', (byte) '1', (byte) '2', (byte) '3', // 52 to 55 (byte) '4', (byte) '5', (byte) '6', (byte) '7', // 56 to 59 (byte) '8', (byte) '9', (byte) '+', (byte) '/' // 60 to 63 }; /** */ private static byte[] ascii = new byte[255]; /** */ static { // not valid bytes for (int idx = 0; idx < 255; idx++) { ascii[idx] = INVALID; } // valid bytes for (int idx = 0; idx < base64.length; idx++) { ascii[base64[idx]] = (byte) idx; } // whitespaces ascii[0x09] = WHITESPACE; ascii[0x0A] = WHITESPACE; ascii[0x0D] = WHITESPACE; ascii[0x20] = WHITESPACE; // trailing equals ascii[0x3d] = EQUAL; } /** * Encode the given byte[]. * * @param src the source string. * @return the base64-encoded data. */ public static final byte[] encode(byte[] src) { return encode(src, 0); } /** * Encode the given byte[]. * * @param src the source string. * @param lineFeed a linefeed is added after <code>linefeed</code> characters; * must be dividable by four; 0 means no linefeeds * @return the base64-encoded data. */ public static final byte[] encode(byte[] src, int lineFeed) { // linefeed must be dividable by 4 lineFeed = lineFeed / 4 * 4; if (lineFeed < 0) { lineFeed = 0; } // determine code length int codeLength = ((src.length + 2) / 3) * 4; if (lineFeed > 0) { codeLength += (codeLength - 1) / lineFeed; } byte[] dst = new byte[codeLength]; int bits24; int bits6; // // Do 3-byte to 4-byte conversion + 0-63 to ascii printable conversion // int didx = 0; int sidx = 0; int lf = 0; while (sidx + 3 <= src.length) { bits24 = (src[sidx++] & 0xFF) << 16; bits24 |= (src[sidx++] & 0xFF) << 8; bits24 |= (src[sidx++] & 0xFF) << 0; bits6 = (bits24 & 0x00FC0000) >> 18; dst[didx++] = base64[bits6]; bits6 = (bits24 & 0x0003F000) >> 12; dst[didx++] = base64[bits6]; bits6 = (bits24 & 0x00000FC0) >> 6; dst[didx++] = base64[bits6]; bits6 = (bits24 & 0x0000003F); dst[didx++] = base64[bits6]; lf += 4; if (didx < codeLength && lineFeed > 0 && lf % lineFeed == 0) { dst[didx++] = 0x0A; } } if (src.length - sidx == 2) { bits24 = (src[sidx] & 0xFF) << 16; bits24 |= (src[sidx + 1] & 0xFF) << 8; bits6 = (bits24 & 0x00FC0000) >> 18; dst[didx++] = base64[bits6]; bits6 = (bits24 & 0x0003F000) >> 12; dst[didx++] = base64[bits6]; bits6 = (bits24 & 0x00000FC0) >> 6; dst[didx++] = base64[bits6]; dst[didx++] = (byte) '='; } else if (src.length - sidx == 1) { bits24 = (src[sidx] & 0xFF) << 16; bits6 = (bits24 & 0x00FC0000) >> 18; dst[didx++] = base64[bits6]; bits6 = (bits24 & 0x0003F000) >> 12; dst[didx++] = base64[bits6]; dst[didx++] = (byte) '='; dst[didx++] = (byte) '='; } return dst; } /** * Encode the given string. * @param src the source string. * @return the base64-encoded string. */ public static final String encode(String src) { return new String(encode(src.getBytes())); } /** * Decode the given byte[]. * * @param src * the base64-encoded data. * @return the decoded data. * @throws IllegalArgumentException Thrown if the base 64 strings contains non-valid characters, * beside the bas64 chars, LF, CR, tab and space are accepted. */ public static final byte[] decode(byte[] src) throws IllegalArgumentException { // // Do ascii printable to 0-63 conversion. // int sidx; int srcLen = 0; for (sidx = 0; sidx < src.length; sidx++) { byte val = ascii[src[sidx]]; if (val >= 0) { src[srcLen++] = val; } else if (val == INVALID) { throw new IllegalArgumentException("Invalid base 64 string"); } } // // Trim any padding. // while (srcLen > 0 && src[srcLen - 1] == EQUAL) { srcLen--; } byte[] dst = new byte[srcLen * 3 / 4]; // // Do 4-byte to 3-byte conversion. // int didx; for (sidx = 0, didx = 0; didx < dst.length - 2; sidx += 4, didx += 3) { dst[didx] = (byte) (((src[sidx] << 2) & 0xFF) | ((src[sidx + 1] >>> 4) & 0x03)); dst[didx + 1] = (byte) (((src[sidx + 1] << 4) & 0xFF) | ((src[sidx + 2] >>> 2) & 0x0F)); dst[didx + 2] = (byte) (((src[sidx + 2] << 6) & 0xFF) | ((src[sidx + 3]) & 0x3F)); } if (didx < dst.length) { dst[didx] = (byte) (((src[sidx] << 2) & 0xFF) | ((src[sidx + 1] >>> 4) & 0x03)); } if (++didx < dst.length) { dst[didx] = (byte) (((src[sidx + 1] << 4) & 0xFF) | ((src[sidx + 2] >>> 2) & 0x0F)); } return dst; } /** * Decode the given string. * * @param src the base64-encoded string. * @return the decoded string. */ public static final String decode(String src) { return new String(decode(src.getBytes())); } }