guiserver/java/Base64Coder.java

   1 /**
   2 * A Base64 Encoder/Decoder.
   3 *
   4 * <p>
   5 * This class is used to encode and decode data in Base64 format as described in RFC 1521.
   6 *
   7 * <p>
   8 * This is "Open Source" software and released under the <a href="http://www.gnu.org/licenses/lgpl.html">GNU/LGPL</a> license.<br>
   9 * It is provided "as is" without warranty of any kind.<br>
  10 * Copyright 2003: Christian d'Heureuse, Inventec Informatik AG, Switzerland.<br>
  11 * Home page: <a href="http://www.source-code.biz">www.source-code.biz</a><br>
  12 *
  13 * <p>
  14 * Version history:<br>
  15 * 2003-07-22 Christian d'Heureuse (chdh): Module created.<br>
  16 * 2005-08-11 chdh: Lincense changed from GPL to LGPL.<br>
  17 * 2006-11-21 chdh:<br>
  18 *  &nbsp; Method encode(String) renamed to encodeString(String).<br>
  19 *  &nbsp; Method decode(String) renamed to decodeString(String).<br>
  20 *  &nbsp; New method encode(byte[],int) added.<br>
  21 *  &nbsp; New method decode(String) added.<br>
  22 */
  23
  24
  25 public class Base64Coder {
  26
  27 // Mapping table from 6-bit nibbles to Base64 characters.
  28 private static char[]    map1 = new char[64];
  29    static {
  30       int i=0;
  31       for (char c='A'; c<='Z'; c++) map1[i++] = c;
  32       for (char c='a'; c<='z'; c++) map1[i++] = c;
  33       for (char c='0'; c<='9'; c++) map1[i++] = c;
  34       map1[i++] = '+'; map1[i++] = '/'; }
  35
  36 // Mapping table from Base64 characters to 6-bit nibbles.
  37 private static byte[]    map2 = new byte[128];
  38    static {
  39       for (int i=0; i<map2.length; i++) map2[i] = -1;
  40       for (int i=0; i<64; i++) map2[map1[i]] = (byte)i; }
  41
  42 /**
  43 * Encodes a string into Base64 format.
  44 * No blanks or line breaks are inserted.
  45 * @param s  a String to be encoded.
  46 * @return   A String with the Base64 encoded data.
  47 */
  48 public static String encodeString (String s) {
  49    return new String(encode(s.getBytes())); }
  50
  51 /**
  52 * Encodes a byte array into Base64 format.
  53 * No blanks or line breaks are inserted.
  54 * @param in  an array containing the data bytes to be encoded.
  55 * @return    A character array with the Base64 encoded data.
  56 */
  57 public static char[] encode (byte[] in) {
  58    return encode(in,in.length); }
  59
  60 /**
  61 * Encodes a byte array into Base64 format.
  62 * No blanks or line breaks are inserted.
  63 * @param in   an array containing the data bytes to be encoded.
  64 * @param iLen number of bytes to process in <code>in</code>.
  65 * @return     A character array with the Base64 encoded data.
  66 */
  67 public static char[] encode (byte[] in, int iLen) {
  68    int oDataLen = (iLen*4+2)/3;       // output length without padding
  69    int oLen = ((iLen+2)/3)*4;         // output length including padding
  70    char[] out = new char[oLen];
  71    int ip = 0;
  72    int op = 0;
  73    while (ip < iLen) {
  74       int i0 = in[ip++] & 0xff;
  75       int i1 = ip < iLen ? in[ip++] & 0xff : 0;
  76       int i2 = ip < iLen ? in[ip++] & 0xff : 0;
  77       int o0 = i0 >>> 2;
  78       int o1 = ((i0 &   3) << 4) | (i1 >>> 4);
  79       int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
  80       int o3 = i2 & 0x3F;
  81       out[op++] = map1[o0];
  82       out[op++] = map1[o1];
  83       out[op] = op < oDataLen ? map1[o2] : '='; op++;
  84       out[op] = op < oDataLen ? map1[o3] : '='; op++; }
  85    return out; }
  86
  87 /**
  88 * Decodes a string from Base64 format.
  89 * @param s  a Base64 String to be decoded.
  90 * @return   A String containing the decoded data.
  91 * @throws   IllegalArgumentException if the input is not valid Base64 encoded data.
  92 */
  93 public static String decodeString (String s) {
  94         if(s.equals("nil")) return("");
  95    return new String(decode(s)); }
  96
  97 /**
  98 * Decodes a byte array from Base64 format.
  99 * @param s  a Base64 String to be decoded.
 100 * @return   An array containing the decoded data bytes.
 101 * @throws   IllegalArgumentException if the input is not valid Base64 encoded data.
 102 */
 103 public static byte[] decode (String s) {
 104    return decode(s.toCharArray()); }
 105
 106 /**
 107 * Decodes a byte array from Base64 format.
 108 * No blanks or line breaks are allowed within the Base64 encoded data.
 109 * @param in  a character array containing the Base64 encoded data.
 110 * @return    An array containing the decoded data bytes.
 111 * @throws    IllegalArgumentException if the input is not valid Base64 encoded data.
 112 */
 113 public static byte[] decode (char[] in) {
 114    int iLen = in.length;
 115    if (iLen%4 != 0) throw new IllegalArgumentException ("Length of Base64 encoded input string is not a multiple of 4.");
 116    while (iLen > 0 && in[iLen-1] == '=') iLen--;
 117    int oLen = (iLen*3) / 4;
 118    byte[] out = new byte[oLen];
 119    int ip = 0;
 120    int op = 0;
 121    while (ip < iLen) {
 122       int i0 = in[ip++];
 123       int i1 = in[ip++];
 124       int i2 = ip < iLen ? in[ip++] : 'A';
 125       int i3 = ip < iLen ? in[ip++] : 'A';
 126       if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
 127          throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
 128       int b0 = map2[i0];
 129       int b1 = map2[i1];
 130       int b2 = map2[i2];
 131       int b3 = map2[i3];
 132       if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
 133          throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
 134       int o0 = ( b0       <<2) | (b1>>>4);
 135       int o1 = ((b1 & 0xf)<<4) | (b2>>>2);
 136       int o2 = ((b2 &   3)<<6) |  b3;
 137       out[op++] = (byte)o0;
 138       if (op<oLen) out[op++] = (byte)o1;
 139       if (op<oLen) out[op++] = (byte)o2; }
 140    return out; }
 141
 142 // Dummy constructor.
 143 private Base64Coder() {}
 144
 145 } // end class Base64Coder
 146
 147
 148 // eof //