JAVA Implementation of base64 encoding/Decoding

/** <Br/> * base64util for Java <br/> * cheungmine <br/> * 2009-11-8 <br/> */<br/> public class base64util {<br/ >/** <br/> * @ Param ARGs <br/> */<br/> Public static void main (string [] ARGs) <br/>{< br/> // Source byte array <br/> int cb = 0; <br/> system. out. print ("Source byte array:"); </P> <p> byte in [] = new byte [100]; <br/> in [CB ++] = '1'; <br/> in [CB ++] = '2 '; <br/> in [CB ++] = '3'; <br/> in [CB ++] = '4 '; <br/> in [CB ++] = '5'; </P> <p> syst Em. out. write (in, 0, CB); </P> <p> // size of the output bytes required for encoding <br/> int cbout = encodestring (in, CB, null, 0); </P> <p> // allocate an array to the output <br/> byte out [] = new byte [cbout]; </P> <p> // start encoding <br/> encodestring (in, CB, out, 0 ); </P> <p> // output the encoding content <br/> system. out. print ("/n encoded content:"); <br/> system. out. write (Out, 0, cbout); </P> <p> // calculate the required bytes for decoding <br/> int cbdec = decodestring (Out, cbout, null ); </P> <p> // assign a decoding array <br/> byte dec [] = new byte [Cbdec]; </P> <p> // start decoding <br/> decodestring (Out, cbout, DEC); </P> <p> // output the decoding result, this result should be consistent with the output <br/> system. out. print ("/n decoding Result:"); <br/> system. out. write (Dec, 0, cbdec ); <br/>}</P> <p>/** <br/> * translation table as described in rfc1113 <br/> */<br/> static string cb64 = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789 + /"; <br/>/** <br/> * translation table to decode (created by author) <br/> */<Br/> static string cd64 = "| $} rstuvwxyz {$ $>? @ Abcdefghijklmnopqrstuvw $ XYZ [//] ^ _ 'abcdefghijklmnopq "; <br/>/** <br/> * encodeblock <br/> * encode 3 8-bit binary bytes (in) as 4 '6-bit 'characters (out) <br/> */<br/> static void encodeblock (byte in [], byte out [], int Len) <br/>{< br/> out [0] = (byte) cb64.charat (in [0]> 2); <br/> out [1] = (byte) cb64.charat (in [0] & 0x03) <4) | (in [1] & 0xf0)> 4 )); <br/> out [2] = (byte) (LEN> 1? Cb64.charat (in [1] & 0x0f) <2) | (in [2] & 0xc0)> 6): '= '); <br/> out [3] = (byte) (LEN> 2? Cb64.charat (in [2] & 0x3f): '= '); <br/>}</P> <p>/** <br/> * decodeblock <br/> * decode 4 '6-bit 'characters 3 8-bit binary bytes <br/> */<br/> static void decodeblock (byte in [], byte out []) <br/>{< br/> out [0] = (byte) (in [0] <2 | in [1]> 4 ); <br/> out [1] = (byte) (in [1] <4 | in [2]> 2 ); <br/> out [2] = (byte) (in [2] <6) & 0xc0) | in [3]); <br/>}</P> <p>/** <br/> * ENC Odestring <br/> * base64 encode bytes <br/> * by cheungmine <br/> * outstr is allocated by caller <br/> * length of encoded string is returned (not including end closing '/0 ') <br/> */<br/> Public static int encodestring (byte instr [], int inlen, byte outstr [], int linesize) <br/>{< br/> byte in [] = new byte [3]; <br/> byte out [] = new byte [4]; </P> <p> int Inc = 0, outc = 0, I, Len, blocksout = 0; </P> <p>/* only size of buffer required */<br/> If (outstr = NULL) {<br/> If (linesize = 0) <br/> return (inlen % 3 = 0 )? (Inlen/3) * 4) :( (inlen/3 + 1) * 4); <br/> while (INC <inlen) {<br/> Len = 0; <br/> for (I = 0; I <3; I ++) {<br/> If (INC <inlen) {<br/> Len ++; <br/> Inc ++; <br/>}< br/> If (LEN> 0) {<br/> outc ++ = 4; <br/> blocksout ++; <br/>}< br/> If (blocksout >=( linesize/4) | Inc = inlen) {<br/> If (blocksout> 0) {<br/> outc ++ = 2; <br/>}< br/> blocksout = 0; <br/>}< br/> return outc; <br/>}< br/>/* Actual E Ncoding below */<br/> while (INC <inlen) {<br/> Len = 0; <br/> for (I = 0; I <3; I ++) {<br/> If (INC <inlen) {<br/> Len ++; <br/> in [I] = instr [INC ++]; <br/>}< br/> else {<br/> in [I] = 0; // padding with zero <br/>}< br/> If (LEN> 0) {<br/> encodeblock (In, out, Len ); <br/> for (I = 0; I <4; I ++) {<br/> outstr [outc ++] = out [I]; <br/>}< br/> blocksout ++; <br/>}< br/> If (linesize> 0) {<br /> If (blocksout >=( linesize/4) | Inc = inlen) {<br/> If (blocksout> 0) {<br/> outstr [outc ++] = '/R'; <br/> outstr [outc ++] ='/N '; <br/>}< br/> blocksout = 0; <br/>}< br/> return outc; <br/>}</P> <p>/** <br/> * Add By cheungmine <br/> * 2009-11-1 <br/> */<br/> Public static int decodestring (byte instr [], int inlen, byte outstr []) <br/>{< br/> byte in [] = new byte [4]; <br/> byte out [] = N EW byte [3]; <br/> byte V; <br/> int Inc = 0, outc = 0, I, Len; <br/>/* only size of buffer required */<br/> If (outstr = NULL) {<br/> while (INC <inlen) {<br/> for (LEN = 0, I = 0; I <4 & Inc <inlen; I ++) {<br/> V = 0; <br/> while (INC <= inlen) & (V = 0) {<br/> V = (INC <inlen )? Instr [INC]: 0; <br/> Inc ++; <br/> V = (byte) (v <43 | V> 122 )? 0: cd64.charat (v-43); <br/> If (V> 0) {<br/> V = (byte) (V = '$ ')? 0: V-61); <br/>}< br/> If (INC <= inlen) {<br/> Len ++; <br/>}< br/> If (LEN> 1) {<br/> outc + = (len-1 ); <br/>}< br/> return outc; <br/>}</P> <p> while (INC <inlen) {<br/> for (LEN = 0, I = 0; I <4 & Inc <inlen; I ++) {<br/> V = 0; <br/> while (INC <= inlen) & (V = 0) {<br/> V = (INC <inlen )? Instr [INC]: 0; <br/> Inc ++; <br/> V = (byte) (v <43 | V> 122 )? 0: cd64.charat (v-43); <br/> If (V> 0) {<br/> V = (byte) (V = '$ ')? 0: V-61); <br/>}< br/> If (INC <= inlen) {<br/> Len ++; <br/> If (V> 0) {<br/> in [I] = (byte) (V-1 ); <br/>}< br/> else {<br/> in [I] = 0; <br/>}< br/> If (LEN> 0) {<br/> decodeblock (In, out ); <br/> for (I = 0; I <len-1; I ++) {<br/> outstr [outc ++] = out [I]; <br/>}< br/> return outc; <br/>}< br/>