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/**
* Copyright (c) 2014 by Wen Yu.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Any modifications to this file must keep this entire header intact.
*/
package cafe.string;
import cafe.util.ArrayUtils;
/**
* A simple base64 encoding and decoding utility class. It can also
* encode and decode non ASII characters such as Chinese.
* <p>
* Changed decode method to remove potential problem when decoding
* concatenated encoded strings.
*
* @author Wen Yu, [email protected]
* @version 1.01 04/18/2012
*/
public final class Base64
{
private static final char[] base64Map = // base64 character table
{ 'A','B','C','D','E','F','G','H','I','J','K','L','M','N',
'O','P','Q','R','S','T','U','V','W','X','Y','Z','a','b',
'c','d','e','f','g','h','i','j','k','l','m','n','o','p',
'q','r','s','t','u','v','w','x','y','z','0','1','2','3',
'4','5','6','7','8','9','+','/' } ;
/**
* Convert the platform dependent string characters to UTF8 which can
* also be done by calling the java String method getBytes("UTF-8"),
* but I hope to do it from the ground up.
*/
private static byte[] toUTF8ByteArray(String s)
{
int ichar;
byte buffer[]=new byte[3*(s.length())];
int index=0;
int count=0; // Count the actual bytes in the buffer array
for(int i=0;i<s.length();i++)
{
ichar = s.charAt(i);
// Determine the bytes for a specific character
if((ichar>=0x0080)&(ichar<=0x07FF))
{
buffer[index++] = (byte)((6<<5)|((ichar>>6)&31));
buffer[index++] = (byte)((2<<6)|(ichar&63));
count+=2;
}
// Determine the bytes for a specific character
else if((ichar>=0x0800)&(ichar<=0x0FFFF))
{
buffer[index++] = (byte)((14<<4)|((ichar>>12)&15));
buffer[index++] = (byte)((2<<6)|((ichar>>6)&63));
buffer[index++] = (byte)((2<<6)|(ichar&63));
count+=3;
}
// Determine the bytes for a specific character
else if((ichar>=0x0000)&(ichar<=0x007F))
{
buffer[index++] = (byte)((0<<7)|(ichar&127));
count+=1;
}
// Longer than 16 bit Unicode is not supported
else throw new RuntimeException("Unsupported encoding character length!\n");
}
return ArrayUtils.subArray(buffer, 0, count); // Trim to size
}
public static String encode(String s)
{
byte buf[] = toUTF8ByteArray(s);
return encode(buf);
}
public static String encode(byte buf[])
{
StringBuffer sb = new StringBuffer();
String padder = "" ;
if( buf.length == 0 ) return "" ;
// Cope with less than 3 bytes conditions at the end of buf
switch( buf.length%3)
{
case 1 :
{
padder += base64Map[(( buf[buf.length-1] >>> 2 ) & 63) ] ;
padder += base64Map[ (( buf[buf.length-1] << 4 ) & 63) ] ;
padder += "==" ;
break ;
}
case 2 :
{
padder += base64Map[ ( buf[buf.length-2] >>> 2 ) & 63 ] ;
padder += base64Map[ (((buf[buf.length-2] << 4 )&63)) | ((( buf[buf.length-1] >>>4 ) & 63)) ] ;
padder += base64Map[ ( buf[buf.length-1] << 2 ) & 63 ] ;
padder += "=" ;
break ;
}
default : break ;
}
int temp =0 ;
int index = 0 ;
// Encode buf.length-buf.length%3 bytes which must be a multiply of 3
for( int i=0 ; i < ( buf.length-(buf.length % 3) ) ; )
{
// Get three bytes and encode them to four base64 characters
temp = ((buf[i++] << 16)&0xFF0000)|((buf[i++] << 8)&0xFF00)|(buf[i++]&0xFF) ;
index = (temp >> 18) & 63 ;
sb.append(base64Map[ index ]);
if(sb.length()%76==0)// A Base64 encoded line is no longer than 76 characters
sb.append('\n');
index = (temp >> 12 ) & 63 ;
sb.append(base64Map[ index ]);
if(sb.length()%76==0)
sb.append('\n');
index = (temp >> 6 ) & 63 ;
sb.append(base64Map[ index ]);
if(sb.length()%76==0)
sb.append('\n');
index = temp & 63 ;
sb.append(base64Map[ index ]);
if(sb.length()%76==0)
sb.append('\n');
}
sb.append(padder); // Add the remaining one or two bytes
return sb.toString();
}
public static String decode(String s) throws Exception
{
byte buf[] = decodeToByteArray(s) ;
return new String(buf,"UTF-8") ;
}
public static byte[] decodeToByteArray(String s) throws Exception
{
//byte hold[];
if( s.length() == 0 ) return null ;
byte buf[] = s.getBytes("iso-8859-1") ;
byte debuf[] = new byte[buf.length*3/4] ;
byte tempBuf[]=new byte[4] ;
int index=0;
int index1=0;
int temp;
//int count=0;
//int count1=0;
// Decode to byte array
for(int i=0; i<buf.length;i++)
{
if(buf[i]>=65 && buf[i]<91)
tempBuf[index++]=(byte)(buf[i]-65);
else if(buf[i]>=97 && buf[i]<123)
tempBuf[index++]=(byte)(buf[i]-71);
else if(buf[i]>=48 && buf[i]<58)
tempBuf[index++]=(byte)(buf[i]+4);
else if(buf[i]=='+')
tempBuf[index++]=62;
else if(buf[i]=='/')
tempBuf[index++]=63;
else if(buf[i]=='=')
{
tempBuf[index++]=0;
//count1++;
}
// Discard line breaks and other non-significant characters
else
{
if(buf[i]=='\n' || buf[i]=='\r' || buf[i]==' ' || buf[i]=='\t')
continue;
throw new RuntimeException("Illegal character found in encoded string!");
}
if(index==4)
{
temp=((tempBuf[0]<<18)) | (( tempBuf[1] <<12)) | ((tempBuf[2]<<6)) | (tempBuf[3]) ;
debuf[index1++]=(byte)(temp>>16) ;
debuf[index1++]=(byte)((temp>>8)&255) ;
debuf[index1++]=(byte)(temp&255) ;
//count+=3;
index=0;
}
}
//hold = new byte[count-count1];
//System.arraycopy(debuf,0,hold,0,count-count1); //trim to size
//return hold;
return debuf;
}
}
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