Base64.java

00001 /*
00002  * Copyright 2001-2004 The Apache Software Foundation.
00003  * 
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  * 
00008  *      http://www.apache.org/licenses/LICENSE-2.0
00009  * 
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */ 
00016 
00017 package org.apache.commons.codec.binary;
00018 
00019 import org.apache.commons.codec.BinaryDecoder;
00020 import org.apache.commons.codec.BinaryEncoder;
00021 import org.apache.commons.codec.DecoderException;
00022 import org.apache.commons.codec.EncoderException;
00023 
00036 public class Base64 implements BinaryEncoder, BinaryDecoder {
00037 
00046     static final int CHUNK_SIZE = 76;
00047 
00053     static final byte[] CHUNK_SEPARATOR = "\r\n".getBytes();
00054 
00058     static final int BASELENGTH = 255;
00059 
00063     static final int LOOKUPLENGTH = 64;
00064 
00068     static final int EIGHTBIT = 8;
00069 
00073     static final int SIXTEENBIT = 16;
00074 
00078     static final int TWENTYFOURBITGROUP = 24;
00079 
00083     static final int FOURBYTE = 4;
00084 
00088     static final int SIGN = -128;
00089     
00093     static final byte PAD = (byte) '=';
00094 
00095     // Create arrays to hold the base64 characters and a 
00096     // lookup for base64 chars
00097     private static byte[] base64Alphabet = new byte[BASELENGTH];
00098     private static byte[] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];
00099 
00100     // Populating the lookup and character arrays
00101     static {
00102         for (int i = 0; i < BASELENGTH; i++) {
00103             base64Alphabet[i] = (byte) -1;
00104         }
00105         for (int i = 'Z'; i >= 'A'; i--) {
00106             base64Alphabet[i] = (byte) (i - 'A');
00107         }
00108         for (int i = 'z'; i >= 'a'; i--) {
00109             base64Alphabet[i] = (byte) (i - 'a' + 26);
00110         }
00111         for (int i = '9'; i >= '0'; i--) {
00112             base64Alphabet[i] = (byte) (i - '0' + 52);
00113         }
00114 
00115         base64Alphabet['+'] = 62;
00116         base64Alphabet['/'] = 63;
00117 
00118         for (int i = 0; i <= 25; i++) {
00119             lookUpBase64Alphabet[i] = (byte) ('A' + i);
00120         }
00121 
00122         for (int i = 26, j = 0; i <= 51; i++, j++) {
00123             lookUpBase64Alphabet[i] = (byte) ('a' + j);
00124         }
00125 
00126         for (int i = 52, j = 0; i <= 61; i++, j++) {
00127             lookUpBase64Alphabet[i] = (byte) ('0' + j);
00128         }
00129 
00130         lookUpBase64Alphabet[62] = (byte) '+';
00131         lookUpBase64Alphabet[63] = (byte) '/';
00132     }
00133 
00134     private static boolean isBase64(byte octect) {
00135         if (octect == PAD) {
00136             return true;
00137         } else if (base64Alphabet[octect] == -1) {
00138             return false;
00139         } else {
00140             return true;
00141         }
00142     }
00143 
00152     public static boolean isArrayByteBase64(byte[] arrayOctect) {
00153 
00154         arrayOctect = discardWhitespace(arrayOctect);
00155 
00156         int length = arrayOctect.length;
00157         if (length == 0) {
00158             // shouldn't a 0 length array be valid base64 data?
00159             // return false;
00160             return true;
00161         }
00162         for (int i = 0; i < length; i++) {
00163             if (!isBase64(arrayOctect[i])) {
00164                 return false;
00165             }
00166         }
00167         return true;
00168     }
00169 
00177     public static byte[] encodeBase64(byte[] binaryData) {
00178         return encodeBase64(binaryData, false);
00179     }
00180 
00188     public static byte[] encodeBase64Chunked(byte[] binaryData) {
00189         return encodeBase64(binaryData, true);
00190     }
00191 
00192 
00205     public Object decode(Object pObject) throws DecoderException {
00206         if (!(pObject instanceof byte[])) {
00207             throw new DecoderException("Parameter supplied to Base64 decode is not a byte[]");
00208         }
00209         return decode((byte[]) pObject);
00210     }
00211 
00219     public byte[] decode(byte[] pArray) {
00220         return decodeBase64(pArray);
00221     }
00222 
00232     public static byte[] encodeBase64(byte[] binaryData, boolean isChunked) {
00233         int lengthDataBits = binaryData.length * EIGHTBIT;
00234         int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
00235         int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
00236         byte encodedData[] = null;
00237         int encodedDataLength = 0;
00238         int nbrChunks = 0;
00239 
00240         if (fewerThan24bits != 0) {
00241             //data not divisible by 24 bit
00242             encodedDataLength = (numberTriplets + 1) * 4;
00243         } else {
00244             // 16 or 8 bit
00245             encodedDataLength = numberTriplets * 4;
00246         }
00247 
00248         // If the output is to be "chunked" into 76 character sections, 
00249         // for compliance with RFC 2045 MIME, then it is important to 
00250         // allow for extra length to account for the separator(s)
00251         if (isChunked) {
00252 
00253             nbrChunks =
00254                 (CHUNK_SEPARATOR.length == 0 ? 0 : (int) Math.ceil((float) encodedDataLength / CHUNK_SIZE));
00255             encodedDataLength += nbrChunks * CHUNK_SEPARATOR.length;
00256         }
00257 
00258         encodedData = new byte[encodedDataLength];
00259 
00260         byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
00261 
00262         int encodedIndex = 0;
00263         int dataIndex = 0;
00264         int i = 0;
00265         int nextSeparatorIndex = CHUNK_SIZE;
00266         int chunksSoFar = 0;
00267 
00268         //log.debug("number of triplets = " + numberTriplets);
00269         for (i = 0; i < numberTriplets; i++) {
00270             dataIndex = i * 3;
00271             b1 = binaryData[dataIndex];
00272             b2 = binaryData[dataIndex + 1];
00273             b3 = binaryData[dataIndex + 2];
00274 
00275             //log.debug("b1= " + b1 +", b2= " + b2 + ", b3= " + b3);
00276 
00277             l = (byte) (b2 & 0x0f);
00278             k = (byte) (b1 & 0x03);
00279 
00280             byte val1 =
00281                 ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
00282             byte val2 =
00283                 ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
00284             byte val3 =
00285                 ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);
00286 
00287             encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
00288             //log.debug( "val2 = " + val2 );
00289             //log.debug( "k4   = " + (k<<4) );
00290             //log.debug(  "vak  = " + (val2 | (k<<4)) );
00291             encodedData[encodedIndex + 1] =
00292                 lookUpBase64Alphabet[val2 | (k << 4)];
00293             encodedData[encodedIndex + 2] =
00294                 lookUpBase64Alphabet[(l << 2) | val3];
00295             encodedData[encodedIndex + 3] = lookUpBase64Alphabet[b3 & 0x3f];
00296 
00297             encodedIndex += 4;
00298 
00299             // If we are chunking, let's put a chunk separator down.
00300             if (isChunked) {
00301                 // this assumes that CHUNK_SIZE % 4 == 0
00302                 if (encodedIndex == nextSeparatorIndex) {
00303                     System.arraycopy(
00304                         CHUNK_SEPARATOR,
00305                         0,
00306                         encodedData,
00307                         encodedIndex,
00308                         CHUNK_SEPARATOR.length);
00309                     chunksSoFar++;
00310                     nextSeparatorIndex =
00311                         (CHUNK_SIZE * (chunksSoFar + 1)) + 
00312                         (chunksSoFar * CHUNK_SEPARATOR.length);
00313                     encodedIndex += CHUNK_SEPARATOR.length;
00314                 }
00315             }
00316         }
00317 
00318         // form integral number of 6-bit groups
00319         dataIndex = i * 3;
00320 
00321         if (fewerThan24bits == EIGHTBIT) {
00322             b1 = binaryData[dataIndex];
00323             k = (byte) (b1 & 0x03);
00324             //log.debug("b1=" + b1);
00325             //log.debug("b1<<2 = " + (b1>>2) );
00326             byte val1 =
00327                 ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
00328             encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
00329             encodedData[encodedIndex + 1] = lookUpBase64Alphabet[k << 4];
00330             encodedData[encodedIndex + 2] = PAD;
00331             encodedData[encodedIndex + 3] = PAD;
00332         } else if (fewerThan24bits == SIXTEENBIT) {
00333 
00334             b1 = binaryData[dataIndex];
00335             b2 = binaryData[dataIndex + 1];
00336             l = (byte) (b2 & 0x0f);
00337             k = (byte) (b1 & 0x03);
00338 
00339             byte val1 =
00340                 ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
00341             byte val2 =
00342                 ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
00343 
00344             encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
00345             encodedData[encodedIndex + 1] =
00346                 lookUpBase64Alphabet[val2 | (k << 4)];
00347             encodedData[encodedIndex + 2] = lookUpBase64Alphabet[l << 2];
00348             encodedData[encodedIndex + 3] = PAD;
00349         }
00350 
00351         if (isChunked) {
00352             // we also add a separator to the end of the final chunk.
00353             if (chunksSoFar < nbrChunks) {
00354                 System.arraycopy(
00355                     CHUNK_SEPARATOR,
00356                     0,
00357                     encodedData,
00358                     encodedDataLength - CHUNK_SEPARATOR.length,
00359                     CHUNK_SEPARATOR.length);
00360             }
00361         }
00362 
00363         return encodedData;
00364     }
00365 
00372     public static byte[] decodeBase64(byte[] base64Data) {
00373         // RFC 2045 requires that we discard ALL non-Base64 characters
00374         base64Data = discardNonBase64(base64Data);
00375 
00376         // handle the edge case, so we don't have to worry about it later
00377         if (base64Data.length == 0) {
00378             return new byte[0];
00379         }
00380 
00381         int numberQuadruple = base64Data.length / FOURBYTE;
00382         byte decodedData[] = null;
00383         byte b1 = 0, b2 = 0, b3 = 0, b4 = 0, marker0 = 0, marker1 = 0;
00384 
00385         // Throw away anything not in base64Data
00386 
00387         int encodedIndex = 0;
00388         int dataIndex = 0;
00389         {
00390             // this sizes the output array properly - rlw
00391             int lastData = base64Data.length;
00392             // ignore the '=' padding
00393             while (base64Data[lastData - 1] == PAD) {
00394                 if (--lastData == 0) {
00395                     return new byte[0];
00396                 }
00397             }
00398             decodedData = new byte[lastData - numberQuadruple];
00399         }
00400         
00401         for (int i = 0; i < numberQuadruple; i++) {
00402             dataIndex = i * 4;
00403             marker0 = base64Data[dataIndex + 2];
00404             marker1 = base64Data[dataIndex + 3];
00405             
00406             b1 = base64Alphabet[base64Data[dataIndex]];
00407             b2 = base64Alphabet[base64Data[dataIndex + 1]];
00408             
00409             if (marker0 != PAD && marker1 != PAD) {
00410                 //No PAD e.g 3cQl
00411                 b3 = base64Alphabet[marker0];
00412                 b4 = base64Alphabet[marker1];
00413                 
00414                 decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
00415                 decodedData[encodedIndex + 1] =
00416                     (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
00417                 decodedData[encodedIndex + 2] = (byte) (b3 << 6 | b4);
00418             } else if (marker0 == PAD) {
00419                 //Two PAD e.g. 3c[Pad][Pad]
00420                 decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
00421             } else if (marker1 == PAD) {
00422                 //One PAD e.g. 3cQ[Pad]
00423                 b3 = base64Alphabet[marker0];
00424                 
00425                 decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
00426                 decodedData[encodedIndex + 1] =
00427                     (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
00428             }
00429             encodedIndex += 3;
00430         }
00431         return decodedData;
00432     }
00433     
00441     static byte[] discardWhitespace(byte[] data) {
00442         byte groomedData[] = new byte[data.length];
00443         int bytesCopied = 0;
00444         
00445         for (int i = 0; i < data.length; i++) {
00446             switch (data[i]) {
00447             case (byte) ' ' :
00448             case (byte) '\n' :
00449             case (byte) '\r' :
00450             case (byte) '\t' :
00451                     break;
00452             default:
00453                     groomedData[bytesCopied++] = data[i];
00454             }
00455         }
00456 
00457         byte packedData[] = new byte[bytesCopied];
00458 
00459         System.arraycopy(groomedData, 0, packedData, 0, bytesCopied);
00460 
00461         return packedData;
00462     }
00463 
00473     static byte[] discardNonBase64(byte[] data) {
00474         byte groomedData[] = new byte[data.length];
00475         int bytesCopied = 0;
00476 
00477         for (int i = 0; i < data.length; i++) {
00478             if (isBase64(data[i])) {
00479                 groomedData[bytesCopied++] = data[i];
00480             }
00481         }
00482 
00483         byte packedData[] = new byte[bytesCopied];
00484 
00485         System.arraycopy(groomedData, 0, packedData, 0, bytesCopied);
00486 
00487         return packedData;
00488     }
00489 
00490 
00491     // Implementation of the Encoder Interface
00492 
00505     public Object encode(Object pObject) throws EncoderException {
00506         if (!(pObject instanceof byte[])) {
00507             throw new EncoderException(
00508                 "Parameter supplied to Base64 encode is not a byte[]");
00509         }
00510         return encode((byte[]) pObject);
00511     }
00512 
00520     public byte[] encode(byte[] pArray) {
00521         return encodeBase64(pArray, false);
00522     }
00523 
00524 }

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