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Java > Open Source Codes > org > objectweb > jac > util > Base64


1 //////////////////////license & copyright header/////////////////////////
2 // //
3 // Base64 - encode/decode data using the Base64 encoding scheme //
4 // //
5 // Copyright (c) 1998 by Kevin Kelley //
6 // //
7 // This library is free software; you can redistribute it and/or //
8 // modify it under the terms of the GNU Lesser General Public //
9 // License as published by the Free Software Foundation; either //
10 // version 2.1 of the License, or (at your option) any later version. //
11 // //
12 // This library is distributed in the hope that it will be useful, //
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of //
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
15 // GNU Lesser General Public License for more details. //
16 // //
17 // You should have received a copy of the GNU Lesser General Public //
18 // License along with this library; if not, write to the Free Software //
19 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA //
20 // 02111-1307, USA, or contact the author: //
21 // //
22 // Kevin Kelley <kelley@ruralnet.net> - 30718 Rd. 28, La Junta, CO, //
23 // 81050 USA. //
24 // //
25 ////////////////////end license & copyright header///////////////////////
26
27 package org.objectweb.jac.util;
28
29 import java.io.*; // needed only for main() method.
30
31
32 /**
33  * Provides encoding of raw bytes to base64-encoded characters, and
34  * decoding of base64 characters to raw bytes.
35  *
36  * @author Kevin Kelley (kelley@ruralnet.net)
37  * @version 1.3
38  */
39 public class Base64 {
40
41    /**
42     * returns an array of base64-encoded characters to represent the
43     * passed data array.
44     *
45     * @param data the array of bytes to encode
46     * @return base64-coded character array.
47     */
48    static public char[] encode(byte[] data)
49    {
50       char[] out = new char[((data.length + 2) / 3) * 4];
51
52       //
53 // 3 bytes encode to 4 chars. Output is always an even
54 // multiple of 4 characters.
55 //
56 for (int i=0, index=0; i<data.length; i+=3, index+=4) {
57          boolean quad = false;
58          boolean trip = false;
59
60          int val = (0xFF & (int) data[i]);
61          val <<= 8;
62          if ((i+1) < data.length) {
63             val |= (0xFF & (int) data[i+1]);
64             trip = true;
65          }
66          val <<= 8;
67          if ((i+2) < data.length) {
68             val |= (0xFF & (int) data[i+2]);
69             quad = true;
70          }
71          out[index+3] = alphabet[(quad? (val & 0x3F): 64)];
72          val >>= 6;
73          out[index+2] = alphabet[(trip? (val & 0x3F): 64)];
74          val >>= 6;
75          out[index+1] = alphabet[val & 0x3F];
76          val >>= 6;
77          out[index+0] = alphabet[val & 0x3F];
78       }
79       return out;
80    }
81
82    public static String JavaDoc encodeToString(byte[] data) {
83       return new String JavaDoc(encode(data));
84    }
85
86    /**
87     * Decodes a BASE-64 encoded stream to recover the original
88     * data. White space before and after will be trimmed away,
89     * but no other manipulation of the input will be performed.
90     *
91     * As of version 1.2 this method will properly handle input
92     * containing junk characters (newlines and the like) rather
93     * than throwing an error. It does this by pre-parsing the
94     * input and generating from that a count of VALID input
95     * characters.
96     **/
97    static public byte[] decode(char[] data)
98    {
99       // as our input could contain non-BASE64 data (newlines,
100 // whitespace of any sort, whatever) we must first adjust
101 // our count of USABLE data so that...
102 // (a) we don't misallocate the output array, and
103 // (b) think that we miscalculated our data length
104 // just because of extraneous throw-away junk
105
106       int tempLen = data.length;
107       for( int ix=0; ix<data.length; ix++ )
108       {
109          if( (data[ix] > 255) || codes[ data[ix] ] < 0 )
110             --tempLen; // ignore non-valid chars and padding
111 }
112       // calculate required length:
113 // -- 3 bytes for every 4 valid base64 chars
114 // -- plus 2 bytes if there are 3 extra base64 chars,
115 // or plus 1 byte if there are 2 extra.
116
117       int len = (tempLen / 4) * 3;
118       if ((tempLen % 4) == 3) len += 2;
119       if ((tempLen % 4) == 2) len += 1;
120
121       byte[] out = new byte[len];
122
123
124
125       int shift = 0; // # of excess bits stored in accum
126 int accum = 0; // excess bits
127 int index = 0;
128
129       // we now go through the entire array (NOT using the 'tempLen' value)
130 for (int ix=0; ix<data.length; ix++)
131       {
132          int value = (data[ix]>255)? -1: codes[ data[ix] ];
133
134          if ( value >= 0 ) // skip over non-code
135 {
136             accum <<= 6; // bits shift up by 6 each time thru
137 shift += 6; // loop, with new bits being put in
138 accum |= value; // at the bottom.
139 if ( shift >= 8 ) // whenever there are 8 or more shifted in,
140 {
141                shift -= 8; // write them out (from the top, leaving any
142 out[index++] = // excess at the bottom for next iteration.
143 (byte) ((accum >> shift) & 0xff);
144             }
145          }
146          // we will also have skipped processing a padding null byte ('=') here;
147 // these are used ONLY for padding to an even length and do not legally
148 // occur as encoded data. for this reason we can ignore the fact that
149 // no index++ operation occurs in that special case: the out[] array is
150 // initialized to all-zero bytes to start with and that works to our
151 // advantage in this combination.
152 }
153
154       // if there is STILL something wrong we just have to throw up now!
155 if( index != out.length)
156       {
157          throw new Error JavaDoc("Miscalculated data length (wrote " + index + " instead of " + out.length + ")");
158       }
159
160       return out;
161    }
162
163    public static byte[] decode(String JavaDoc data) {
164       return decode(data.toCharArray());
165    }
166
167    //
168 // code characters for values 0..63
169 //
170 static private char[] alphabet =
171    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
172    .toCharArray();
173
174    //
175 // lookup table for converting base64 characters to value in range 0..63
176 //
177 static private byte[] codes = new byte[256];
178    static {
179       for (int i=0; i<256; i++) codes[i] = -1;
180       for (int i = 'A'; i <= 'Z'; i++) codes[i] = (byte)( i - 'A');
181       for (int i = 'a'; i <= 'z'; i++) codes[i] = (byte)(26 + i - 'a');
182       for (int i = '0'; i <= '9'; i++) codes[i] = (byte)(52 + i - '0');
183       codes['+'] = 62;
184       codes['/'] = 63;
185    }
186
187
188
189
190    ///////////////////////////////////////////////////
191 // remainder (main method and helper functions) is
192 // for testing purposes only, feel free to clip it.
193 ///////////////////////////////////////////////////
194
195    public static void main(String JavaDoc[] args)
196    {
197       boolean decode = false;
198
199       if (args.length == 0) {
200          System.out.println("usage: java Base64 [-d[ecode]] filename");
201          System.exit(0);
202       }
203       for (int i=0; i<args.length; i++) {
204          if ("-decode".equalsIgnoreCase(args[i])) decode = true;
205          else if ("-d".equalsIgnoreCase(args[i])) decode = true;
206       }
207
208       String JavaDoc filename = args[args.length-1];
209       File file = new File(filename);
210       if (!file.exists()) {
211          System.out.println("Error: file '" + filename + "' doesn't exist!");
212          System.exit(0);
213       }
214
215       if (decode)
216       {
217          char[] encoded = readChars(file);
218          byte[] decoded = decode(encoded);
219          writeBytes(file, decoded);
220       }
221       else
222       {
223          byte[] decoded = readBytes(file);
224          char[] encoded = encode(decoded);
225          writeChars(file, encoded);
226       }
227    }
228
229    private static byte[] readBytes(File file)
230    {
231       ByteArrayOutputStream baos = new ByteArrayOutputStream();
232       try
233       {
234          InputStream fis = new FileInputStream(file);
235          InputStream is = new BufferedInputStream(fis);
236          int count = 0;
237          byte[] buf = new byte[16384];
238          while ((count=is.read(buf)) != -1) {
239             if (count > 0) baos.write(buf, 0, count);
240          }
241          is.close();
242       }
243       catch (Exception JavaDoc e) { e.printStackTrace(); }
244
245       return baos.toByteArray();
246    }
247
248    private static char[] readChars(File file)
249    {
250       CharArrayWriter caw = new CharArrayWriter();
251       try
252       {
253          Reader fr = new FileReader(file);
254          Reader in = new BufferedReader(fr);
255          int count = 0;
256          char[] buf = new char[16384];
257          while ((count=in.read(buf)) != -1) {
258             if (count > 0) caw.write(buf, 0, count);
259          }
260          in.close();
261       }
262       catch (Exception JavaDoc e) { e.printStackTrace(); }
263
264       return caw.toCharArray();
265    }
266
267    private static void writeBytes(File file, byte[] data) {
268       try {
269          OutputStream fos = new FileOutputStream(file);
270          OutputStream os = new BufferedOutputStream(fos);
271          os.write(data);
272          os.close();
273       }
274       catch (Exception JavaDoc e) { e.printStackTrace(); }
275    }
276
277    private static void writeChars(File file, char[] data) {
278       try {
279          Writer fos = new FileWriter(file);
280          Writer os = new BufferedWriter(fos);
281          os.write(data);
282          os.close();
283       }
284       catch (Exception JavaDoc e) { e.printStackTrace(); }
285    }
286    ///////////////////////////////////////////////////
287 // end of test code.
288 ///////////////////////////////////////////////////
289
290 }
291
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