ekit/com/hexidec/util/Base64Codec.java

   1 package com.hexidec.util;
   2
   3 import java.util.Vector;
   4
   5 public class Base64Codec
   6 {
   7         public static Vector Base64Tokens = new Vector(64);
   8         static
   9         {
  10                 Base64Tokens.add("A");
  11                 Base64Tokens.add("B");
  12                 Base64Tokens.add("C");
  13                 Base64Tokens.add("D");
  14                 Base64Tokens.add("E");
  15                 Base64Tokens.add("F");
  16                 Base64Tokens.add("G");
  17                 Base64Tokens.add("H");
  18                 Base64Tokens.add("I");
  19                 Base64Tokens.add("J");
  20                 Base64Tokens.add("K");
  21                 Base64Tokens.add("L");
  22                 Base64Tokens.add("M");
  23                 Base64Tokens.add("N");
  24                 Base64Tokens.add("O");
  25                 Base64Tokens.add("P");
  26                 Base64Tokens.add("Q");
  27                 Base64Tokens.add("R");
  28                 Base64Tokens.add("S");
  29                 Base64Tokens.add("T");
  30                 Base64Tokens.add("U");
  31                 Base64Tokens.add("V");
  32                 Base64Tokens.add("W");
  33                 Base64Tokens.add("X");
  34                 Base64Tokens.add("Y");
  35                 Base64Tokens.add("Z");
  36                 Base64Tokens.add("a");
  37                 Base64Tokens.add("b");
  38                 Base64Tokens.add("c");
  39                 Base64Tokens.add("d");
  40                 Base64Tokens.add("e");
  41                 Base64Tokens.add("f");
  42                 Base64Tokens.add("g");
  43                 Base64Tokens.add("h");
  44                 Base64Tokens.add("i");
  45                 Base64Tokens.add("j");
  46                 Base64Tokens.add("k");
  47                 Base64Tokens.add("l");
  48                 Base64Tokens.add("m");
  49                 Base64Tokens.add("n");
  50                 Base64Tokens.add("o");
  51                 Base64Tokens.add("p");
  52                 Base64Tokens.add("q");
  53                 Base64Tokens.add("r");
  54                 Base64Tokens.add("s");
  55                 Base64Tokens.add("t");
  56                 Base64Tokens.add("u");
  57                 Base64Tokens.add("v");
  58                 Base64Tokens.add("w");
  59                 Base64Tokens.add("x");
  60                 Base64Tokens.add("y");
  61                 Base64Tokens.add("z");
  62                 Base64Tokens.add("0");
  63                 Base64Tokens.add("1");
  64                 Base64Tokens.add("2");
  65                 Base64Tokens.add("3");
  66                 Base64Tokens.add("4");
  67                 Base64Tokens.add("5");
  68                 Base64Tokens.add("6");
  69                 Base64Tokens.add("7");
  70                 Base64Tokens.add("8");
  71                 Base64Tokens.add("9");
  72                 Base64Tokens.add("+");
  73                 Base64Tokens.add("/");
  74         }
  75         public static final char Base64Pad = '=';
  76         public static final char Linefeed = (char)10;
  77         public static final char Carriage = (char)13;
  78         public static final int  LineMax = 75;
  79
  80         public Base64Codec()
  81         {
  82         }
  83
  84         public static String encode(String source)
  85         {
  86                 byte[] sourceBytes = source.getBytes();
  87                 int byteTriad = sourceBytes.length % 3;
  88                 StringBuffer encoding = new StringBuffer();
  89                 int bitOffset = 7;
  90                 int b64Offset = 5;
  91                 int bytePlace = 0;
  92                 byte tokenValue = (byte)0;
  93                 int lineLength = 0;
  94                 while(bytePlace < sourceBytes.length)
  95                 {
  96                         tokenValue = (byte)((byte)tokenValue | (byte)((sourceBytes[bytePlace] & (1 << bitOffset)) > 0 ? (1 << b64Offset) : (byte)0));
  97                         bitOffset--;
  98                         if(bitOffset < 0)
  99                         {
 100                                 bitOffset = 7;
 101                                 bytePlace++;
 102                         }
 103                         b64Offset--;
 104                         if(b64Offset < 0)
 105                         {
 106                                 b64Offset = 5;
 107                                 encoding.append((String)(Base64Tokens.elementAt(tokenValue)));
 108                                 tokenValue = (byte)0;
 109                                 lineLength++;
 110                                 if(lineLength > LineMax)
 111                                 {
 112                                         encoding.append(Carriage);
 113                                         encoding.append(Linefeed);
 114                                         lineLength = 0;
 115                                 }
 116                         }
 117                 }
 118                 if(b64Offset != 5)
 119                 {
 120                         bytePlace--;
 121                         for(int i = b64Offset; i >= 0; i--)
 122                         {
 123                                 if(bitOffset >= 0)
 124                                 {
 125                                         tokenValue = (byte)((byte)tokenValue | (byte)((sourceBytes[bytePlace] & (1 << bitOffset)) > 0 ? (1 << i) : (byte)0));
 126                                 }
 127                                 bitOffset--;
 128                         }
 129                         encoding.append((String)(Base64Tokens.elementAt(tokenValue)));
 130                 }
 131                 if(byteTriad == 2)
 132                 {
 133                         encoding.append(Base64Pad);
 134                 }
 135                 else if(byteTriad == 1)
 136                 {
 137                         encoding.append(Base64Pad);
 138                         encoding.append(Base64Pad);
 139                 }
 140                 return encoding.toString();
 141         }
 142
 143         public static String decode(String source)
 144         {
 145                 StringBuffer decoding = new StringBuffer();
 146                 int bitOffset = 7;
 147                 int b64Offset = 5;
 148                 int bytePlace = 0;
 149                 byte charValue = (byte)0;
 150                 while(bytePlace < source.length())
 151                 {
 152                         if(source.charAt(bytePlace) == Base64Pad)
 153                         {
 154                                 // end processing when encountering special end-padding character
 155                                 break;
 156                         }
 157                         if(source.charAt(bytePlace) == Linefeed || source.charAt(bytePlace) == Carriage)
 158                         {
 159                                 // ignore standard line break characters
 160                                 bytePlace++;
 161                                 continue;
 162                         }
 163                         else
 164                         {
 165                                 if(!Base64Tokens.contains(source.substring(bytePlace, bytePlace + 1)))
 166                                 {
 167                                         // ignore unknown characters (mostly implemented to deal with other line break character sequences)
 168                                         bytePlace++;
 169                                         continue;
 170                                 }
 171                                 else
 172                                 {
 173                                         byte currentByte = (byte)(Base64Tokens.indexOf(source.substring(bytePlace, bytePlace + 1)));
 174                                         charValue = (byte)((byte)charValue | (byte)((currentByte & (1 << b64Offset)) > 0 ? (1 << bitOffset) : (byte)0));
 175                                         bitOffset--;
 176                                         if(bitOffset < 0)
 177                                         {
 178                                                 bitOffset = 7;
 179                                                 decoding.append((char)charValue);
 180                                                 charValue = (byte)0;
 181                                         }
 182                                         b64Offset--;
 183                                         if(b64Offset < 0)
 184                                         {
 185                                                 b64Offset = 5;
 186                                                 bytePlace++;
 187                                         }
 188                                 }
 189                         }
 190                 }
 191                 return decoding.toString();
 192         }
 193 }