📄 base64.java
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/*
* Copyright (C) 2006-2007 Funambol
*
* 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.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package com.funambol.util;
import java.io.UnsupportedEncodingException;
public class Base64 {
private static final byte[] encodingTable =
{ (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F',
(byte)'G', (byte)'H', (byte)'I', (byte)'J', (byte)'K',
(byte)'L', (byte)'M', (byte)'N', (byte)'O', (byte)'P',
(byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U',
(byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z',
(byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e',
(byte)'f', (byte)'g', (byte)'h', (byte)'i', (byte)'j',
(byte)'k', (byte)'l', (byte)'m', (byte)'n', (byte)'o',
(byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t',
(byte)'u', (byte)'v', (byte)'w', (byte)'x', (byte)'y',
(byte)'z', (byte)'0', (byte)'1', (byte)'2', (byte)'3',
(byte)'4', (byte)'5', (byte)'6', (byte)'7', (byte)'8',
(byte)'9', (byte)'+', (byte)'/' };
/**
* encode the input data producong a base 64 encoded byte array.
*
* @return a byte array containing the base 64 encoded data.
*/
public static byte[] encode(byte[] data) {
byte[] bytes;
int modulus = data.length % 3;
if (modulus == 0) {
bytes = new byte[4 * data.length / 3];
} else {
bytes = new byte[4 * ((data.length / 3) + 1)];
}
int dataLength = (data.length - modulus);
int a1, a2, a3;
for (int i = 0, j = 0; i < dataLength; i += 3, j += 4) {
a1 = data[i] & 0xff;
a2 = data[i + 1] & 0xff;
a3 = data[i + 2] & 0xff;
bytes[j] = encodingTable[(a1 >>> 2) & 0x3f];
bytes[j + 1] = encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3f];
bytes[j + 2] = encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3f];
bytes[j + 3] = encodingTable[a3 & 0x3f];
}
/*
* process the tail end.
*/
int b1, b2, b3;
int d1, d2;
switch (modulus) {
case 0: /* nothing left to do */
break;
case 1:
d1 = data[data.length - 1] & 0xff;
b1 = (d1 >>> 2) & 0x3f;
b2 = (d1 << 4) & 0x3f;
bytes[bytes.length - 4] = encodingTable[b1];
bytes[bytes.length - 3] = encodingTable[b2];
bytes[bytes.length - 2] = (byte)'=';
bytes[bytes.length - 1] = (byte)'=';
break;
case 2:
d1 = data[data.length - 2] & 0xff;
d2 = data[data.length - 1] & 0xff;
b1 = (d1 >>> 2) & 0x3f;
b2 = ((d1 << 4) | (d2 >>> 4)) & 0x3f;
b3 = (d2 << 2) & 0x3f;
bytes[bytes.length - 4] = encodingTable[b1];
bytes[bytes.length - 3] = encodingTable[b2];
bytes[bytes.length - 2] = encodingTable[b3];
bytes[bytes.length - 1] = (byte)'=';
break;
}
return bytes;
}
/*
* set up the decoding table.
*/
private static final byte[] decodingTable;
static {
decodingTable = new byte[128];
for (int i = 0; i < 128; i++) {
decodingTable[i] = (byte)-1;
}
for (int i = 'A'; i <= 'Z'; i++) {
decodingTable[i] = (byte)(i - 'A');
}
for (int i = 'a'; i <= 'z'; i++) {
decodingTable[i] = (byte)(i - 'a' + 26);
}
for (int i = '0'; i <= '9'; i++) {
decodingTable[i] = (byte)(i - '0' + 52);
}
decodingTable['+'] = 62;
decodingTable['/'] = 63;
}
/**
* decode the base 64 encoded input data.
*
* @return a byte array representing the decoded data.
*/
public static byte[] decode(byte[] data) {
byte[] bytes;
byte b1, b2, b3, b4;
data = discardNonBase64Bytes(data);
if (data[data.length - 2] == '=') {
bytes = new byte[(((data.length / 4) - 1) * 3) + 1];
} else if (data[data.length - 1] == '=') {
bytes = new byte[(((data.length / 4) - 1) * 3) + 2];
} else {
bytes = new byte[((data.length / 4) * 3)];
}
for (int i = 0, j = 0; i < data.length - 4; i += 4, j += 3) {
b1 = decodingTable[data[i]];
b2 = decodingTable[data[i + 1]];
b3 = decodingTable[data[i + 2]];
b4 = decodingTable[data[i + 3]];
bytes[j] = (byte)((b1 << 2) | (b2 >> 4));
bytes[j + 1] = (byte)((b2 << 4) | (b3 >> 2));
bytes[j + 2] = (byte)((b3 << 6) | b4);
}
if (data[data.length - 2] == '=') {
b1 = decodingTable[data[data.length - 4]];
b2 = decodingTable[data[data.length - 3]];
bytes[bytes.length - 1] = (byte)((b1 << 2) | (b2 >> 4));
} else if (data[data.length - 1] == '=') {
b1 = decodingTable[data[data.length - 4]];
b2 = decodingTable[data[data.length - 3]];
b3 = decodingTable[data[data.length - 2]];
bytes[bytes.length - 2] = (byte)((b1 << 2) | (b2 >> 4));
bytes[bytes.length - 1] = (byte)((b2 << 4) | (b3 >> 2));
} else {
b1 = decodingTable[data[data.length - 4]];
b2 = decodingTable[data[data.length - 3]];
b3 = decodingTable[data[data.length - 2]];
b4 = decodingTable[data[data.length - 1]];
bytes[bytes.length - 3] = (byte)((b1 << 2) | (b2 >> 4));
bytes[bytes.length - 2] = (byte)((b2 << 4) | (b3 >> 2));
bytes[bytes.length - 1] = (byte)((b3 << 6) | b4);
}
return bytes;
}
/**
* decode the base 64 encoded String data.
*
* TODO: Use the byte version to avoid duplication?
*
* @return a byte array representing the decoded data.
*/
public static byte[] decode(String data) {
byte[] bytes;
byte b1, b2, b3, b4;
data = discardNonBase64Chars(data);
if (data.charAt(data.length() - 2) == '=') {
bytes = new byte[(((data.length() / 4) - 1) * 3) + 1];
} else if (data.charAt(data.length() - 1) == '=') {
bytes = new byte[(((data.length() / 4) - 1) * 3) + 2];
} else {
bytes = new byte[((data.length() / 4) * 3)];
}
for (int i = 0, j = 0; i < data.length() - 4; i += 4, j += 3) {
b1 = decodingTable[data.charAt(i)];
b2 = decodingTable[data.charAt(i + 1)];
b3 = decodingTable[data.charAt(i + 2)];
b4 = decodingTable[data.charAt(i + 3)];
bytes[j] = (byte)((b1 << 2) | (b2 >> 4));
bytes[j + 1] = (byte)((b2 << 4) | (b3 >> 2));
bytes[j + 2] = (byte)((b3 << 6) | b4);
}
if (data.charAt(data.length() - 2) == '=') {
b1 = decodingTable[data.charAt(data.length() - 4)];
b2 = decodingTable[data.charAt(data.length() - 3)];
bytes[bytes.length - 1] = (byte)((b1 << 2) | (b2 >> 4));
} else if (data.charAt(data.length() - 1) == '=') {
b1 = decodingTable[data.charAt(data.length() - 4)];
b2 = decodingTable[data.charAt(data.length() - 3)];
b3 = decodingTable[data.charAt(data.length() - 2)];
bytes[bytes.length - 2] = (byte)((b1 << 2) | (b2 >> 4));
bytes[bytes.length - 1] = (byte)((b2 << 4) | (b3 >> 2));
} else {
b1 = decodingTable[data.charAt(data.length() - 4)];
b2 = decodingTable[data.charAt(data.length() - 3)];
b3 = decodingTable[data.charAt(data.length() - 2)];
b4 = decodingTable[data.charAt(data.length() - 1)];
bytes[bytes.length - 3] = (byte)((b1 << 2) | (b2 >> 4));
bytes[bytes.length - 2] = (byte)((b2 << 4) | (b3 >> 2));
bytes[bytes.length - 1] = (byte)((b3 << 6) | b4);
}
return bytes;
}
/**
* Decode the string and convert back the decoded value into a string
* using the specified charset.
* Use default encoding if charset is null or invalid.
*/
public static String decode(String data, String charset) {
if (charset == null){
// use default
return new String(Base64.decode(data));
}
try {
return new String(Base64.decode(data), charset);
} catch (UnsupportedEncodingException ex) {
Log.error("Charset: "+charset+" not supported. Using default.");
return new String(Base64.decode(data));
}
}
/**
* Decode the string and convert back the decoded value into a string
* using the specified charset.
* Use default encoding if charset is null or invalid.
*/
public static String decode(byte[] data, String charset) {
if (charset == null){
// use default
return new String(Base64.decode(data));
}
try {
return new String(Base64.decode(data), charset);
} catch (UnsupportedEncodingException ex) {
Log.error("Charset: "+charset+" not supported. Using default.");
return new String(Base64.decode(data));
}
}
// --------------------------------------------------------- Private Methods
/**
* Discards any characters outside of the base64 alphabet (see page 25 of
* RFC 2045) "Any characters outside of the base64 alphabet are to be
* ignored in base64 encoded data."
*
* @param data
* the base64 encoded data
* @return the data, less non-base64 characters.
*/
private static byte[] discardNonBase64Bytes(byte[] data) {
byte temp[] = new byte[data.length];
int bytesCopied = 0;
for (int i = 0; i < data.length; i++) {
if (isValidBase64Byte(data[i])) {
temp[bytesCopied++] = data[i];
}
}
byte newData[] = new byte[bytesCopied];
System.arraycopy(temp, 0, newData, 0, bytesCopied);
return newData;
}
/**
* Discards any characters outside of the base64 alphabet (see page 25 of
* RFC 2045) "Any characters outside of the base64 alphabet are to be
* ignored in base64 encoded data."
*
* @param data
* the base64 encoded data
* @return the data, less non-base64 characters.
*/
private static String discardNonBase64Chars(String data) {
StringBuffer sb = new StringBuffer();
int length = data.length();
for (int i = 0; i < length; i++) {
if (isValidBase64Byte((byte)(data.charAt(i)))) {
sb.append(data.charAt(i));
}
}
return sb.toString();
}
/**
* Checks is the given byte is in base64 alphabet
*
* @param b
* the byte to check
* @return boolean true if the byte is in base64 alphabet
*/
private static boolean isValidBase64Byte(byte b) {
if (b == '=') {
return true;
} else if (b < 0 || b >= 128) {
return false;
} else if (decodingTable[b] == -1) {
return false;
}
return true;
}
}
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