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Object Automation library
package com.viaoa.util;
/**
* Provides encoding of raw bytes to base64-encoded characters, and
* decoding of base64 characters to raw bytes.
*/
public class Base64 {
/**
Static method to encode a String using Base64.
@param str string to encode
@return null if str is null, otherwise base64 encoded String.
@see #decode
*/
static public String encode(String str) {
if (str == null) return null;
return new String( encode(str.getBytes()) );
}
/**
returns an array of base64-encoded characters to represent the
passed data array.
@param data the array of bytes to encode
@return base64-coded character array.
*/
static public char[] encode(byte[] data)
{
char[] out = new char[((data.length + 2) / 3) * 4];
//
// 3 bytes encode to 4 chars. Output is always an even
// multiple of 4 characters.
//
for (int i=0, index=0; i>= 6;
out[index+2] = alphabet[(trip? (val & 0x3F): 64)];
val >>= 6;
out[index+1] = alphabet[val & 0x3F];
val >>= 6;
out[index+0] = alphabet[val & 0x3F];
}
return out;
}
/**
Decodes a String that is encoded using Base64 encoding.
@param s is the encoded String that will be decoded.
*/
static public String decode(String s) {
if (s == null) return null;
char[] c = new char[s.length()];
s.getChars(0, s.length(),c, 0);
return new String( decode(c) );
}
/**
* Returns an array of bytes which were encoded in the passed
* character array.
*
* @param data the array of base64-encoded characters
* @return decoded data array
*/
static public byte[] decode(char[] data)
{
int len = ((data.length + 3) / 4) * 3;
if (data.length>0 && data[data.length-1] == '=') --len;
if (data.length>1 && data[data.length-2] == '=') --len;
byte[] out = new byte[len];
int shift = 0; // # of excess bits stored in accum
int accum = 0; // excess bits
int index = 0;
for (int ix=0; ix= 0 ) { // skip over non-code
accum <<= 6; // bits shift up by 6 each time thru
shift += 6; // loop, with new bits being put in
accum |= value; // at the bottom.
if ( shift >= 8 ) { // whenever there are 8 or more shifted in,
shift -= 8; // write them out (from the top, leaving any
out[index++] = // excess at the bottom for next iteration.
(byte) ((accum >> shift) & 0xff);
} } }
if (index != out.length)
throw new Error("miscalculated data length!");
return out;
}
//
// code characters for values 0..63
//
static private char[] alphabet =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
.toCharArray();
//
// lookup table for converting base64 characters to value in range 0..63
//
static private byte[] codes = new byte[256];
static {
for (int i=0; i<256; i++) codes[i] = -1;
for (int i = 'A'; i <= 'Z'; i++) codes[i] = (byte)( i - 'A');
for (int i = 'a'; i <= 'z'; i++) codes[i] = (byte)(26 + i - 'a');
for (int i = '0'; i <= '9'; i++) codes[i] = (byte)(52 + i - '0');
codes['+'] = 62;
codes['/'] = 63;
}
public static void main(String[] args) {
String[] ss = {"Vince","Anthony","Via"};
for (int i=0; i " + s2 + " -> " + s3);
}
}
}
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