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@dsiebel
Created April 1, 2011 14:47
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Static encoding / decoding class for Base64
public class Base64 {
private final static char[] ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
private static int[] toInt = new int[128];
static {
for(int i=0; i< ALPHABET.length; i++){
toInt[ALPHABET[i]]= i;
}
}
/**
* Translates the specified byte array into Base64 string.
*
* @param buf the byte array (not null)
* @return the translated Base64 string (not null)
*/
public static String encode(byte[] buf){
int size = buf.length;
char[] ar = new char[((size + 2) / 3) * 4];
int a = 0;
int i=0;
while(i < size){
byte b0 = buf[i++];
byte b1 = (i < size) ? buf[i++] : 0;
byte b2 = (i < size) ? buf[i++] : 0;
int mask = 0x3F;
ar[a++] = ALPHABET[(b0 >> 2) & mask];
ar[a++] = ALPHABET[((b0 << 4) | ((b1 & 0xFF) >> 4)) & mask];
ar[a++] = ALPHABET[((b1 << 2) | ((b2 & 0xFF) >> 6)) & mask];
ar[a++] = ALPHABET[b2 & mask];
}
switch(size % 3){
case 1: ar[--a] = '=';
case 2: ar[--a] = '=';
}
return new String(ar);
}
/**
* Translates the specified Base64 string into a byte array.
*
* @param s the Base64 string (not null)
* @return the byte array (not null)
*/
public static byte[] decode(String s){
int delta = s.endsWith( "==" ) ? 2 : s.endsWith( "=" ) ? 1 : 0;
byte[] buffer = new byte[s.length()*3/4 - delta];
int mask = 0xFF;
int index = 0;
for(int i=0; i< s.length(); i+=4){
int c0 = toInt[s.charAt( i )];
int c1 = toInt[s.charAt( i + 1)];
buffer[index++]= (byte)(((c0 << 2) | (c1 >> 4)) & mask);
if(index >= buffer.length){
return buffer;
}
int c2 = toInt[s.charAt( i + 2)];
buffer[index++]= (byte)(((c1 << 4) | (c2 >> 2)) & mask);
if(index >= buffer.length){
return buffer;
}
int c3 = toInt[s.charAt( i + 3 )];
buffer[index++]= (byte)(((c2 << 6) | c3) & mask);
}
return buffer;
}
}
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