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/************************************************************************** |
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* |
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* A Base64 Encoder/Decoder. |
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* |
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* This class is used to encode and decode data in Base64 format |
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* as described in RFC 1521. |
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* |
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* <p> |
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* Copyright 2003: Christian d'Heureuse, Inventec Informatik AG, Switzerland.<br> |
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* License: This is "Open Source" software and released under the <a href="http://www.gnu.org/licenses/gpl.html" target="_top">GNU/GPL</a> license. |
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* It is provided "as is" without warranty of any kind. Please contact the author for other licensing arrangements.<br> |
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* Home page: <a href="http://www.source-code.biz" target="_top">www.source-code.biz</a><br> |
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* |
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* <p> |
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* Version history:<br> |
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* 2003-07-22 Christian d'Heureuse (chdh): Module created. |
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* |
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**************************************************************************/ |
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package net.sf.basedb.meludi.converter; |
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public class Base64Coder { |
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|
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// Mapping table from 6-bit nibbles to Base64 characters. |
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private static char[] map1 = new char[64]; |
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static { |
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int i=0; |
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for (char c='A'; c<='Z'; c++) map1[i++] = c; |
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for (char c='a'; c<='z'; c++) map1[i++] = c; |
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for (char c='0'; c<='9'; c++) map1[i++] = c; |
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map1[i++] = '+'; map1[i++] = '/'; } |
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|
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// Mapping table from Base64 characters to 6-bit nibbles. |
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private static byte[] map2 = new byte[128]; |
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static { |
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for (int i=0; i<map2.length; i++) map2[i] = -1; |
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for (int i=0; i<64; i++) map2[map1[i]] = (byte)i; } |
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|
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/** |
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* Encodes a string into Base64 format. |
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* No blanks or line breaks are inserted. |
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* @param s a String to be encoded. |
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* @return A String with the Base64 encoded data. |
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*/ |
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public static String encode (String s) { |
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return new String(encode(s.getBytes())); } |
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|
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/** |
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* Encodes a byte array into Base64 format. |
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* No blanks or line breaks are inserted. |
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* @param in an array containing the data bytes to be encoded. |
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* @return A character array with the Base64 encoded data. |
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*/ |
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public static char[] encode (byte[] in) { |
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int iLen = in.length; |
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int oDataLen = (iLen*4+2)/3; // output length without padding |
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int oLen = ((iLen+2)/3)*4; // output length including padding |
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char[] out = new char[oLen]; |
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int ip = 0; |
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int op = 0; |
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while (ip < iLen) { |
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int i0 = in[ip++] & 0xff; |
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int i1 = ip < iLen ? in[ip++] & 0xff : 0; |
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int i2 = ip < iLen ? in[ip++] & 0xff : 0; |
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int o0 = i0 >>> 2; |
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int o1 = ((i0 & 3) << 4) | (i1 >>> 4); |
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int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6); |
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int o3 = i2 & 0x3F; |
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out[op++] = map1[o0]; |
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out[op++] = map1[o1]; |
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out[op] = op < oDataLen ? map1[o2] : '='; op++; |
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out[op] = op < oDataLen ? map1[o3] : '='; op++; } |
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return out; } |
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|
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/** |
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* Decodes a Base64 string. |
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* @param s a Base64 String to be decoded. |
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* @return A String containing the decoded data. |
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* @throws IllegalArgumentException if the input is not valid Base64 encoded data. |
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*/ |
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public static String decode (String s) { |
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return new String(decode(s.toCharArray())); } |
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|
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/** |
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* Decodes Base64 data. |
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* No blanks or line breaks are allowed within the Base64 encoded data. |
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* @param in a character array containing the Base64 encoded data. |
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* @return An array containing the decoded data bytes. |
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* @throws IllegalArgumentException if the input is not valid Base64 encoded data. |
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*/ |
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public static byte[] decode (char[] in) { |
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int iLen = in.length; |
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if (iLen%4 != 0) throw new IllegalArgumentException ("Length of Base64 encoded input string is not a multiple of 4."); |
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while (iLen > 0 && in[iLen-1] == '=') iLen--; |
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int oLen = (iLen*3) / 4; |
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byte[] out = new byte[oLen]; |
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int ip = 0; |
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int op = 0; |
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while (ip < iLen) { |
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int i0 = in[ip++]; |
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int i1 = in[ip++]; |
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int i2 = ip < iLen ? in[ip++] : 'A'; |
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int i3 = ip < iLen ? in[ip++] : 'A'; |
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if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127) |
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throw new IllegalArgumentException ("Illegal character in Base64 encoded data."); |
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int b0 = map2[i0]; |
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int b1 = map2[i1]; |
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int b2 = map2[i2]; |
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int b3 = map2[i3]; |
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if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0) |
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throw new IllegalArgumentException ("Illegal character in Base64 encoded data."); |
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int o0 = ( b0 <<2) | (b1>>>4); |
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int o1 = ((b1 & 0xf)<<4) | (b2>>>2); |
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int o2 = ((b2 & 3)<<6) | b3; |
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out[op++] = (byte)o0; |
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if (op<oLen) out[op++] = (byte)o1; |
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if (op<oLen) out[op++] = (byte)o2; } |
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return out; } |
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|
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} |