发信人: zjxyz(xyz)
整理人: zjxyz(2002-01-26 13:53:53), 站内信件
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前段时间看到不少朋友讨论JAVAMAIL，刚好看到这个类，希望对大家有用：）
/*********************************************************************
* BASE 64 encoding of a String or an array of bytes.
*
* See also RFC 1421.
*
* @author
* Unknown
* @author
* David W. Croft
* @version
* 1998-06-08
*********************************************************************/
public class Base64Converter
//////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////
{
public static final char [ ] alphabet = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // 0 to 7
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 8 to 15
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 16 to 23
'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', // 24 to 31
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', // 32 to 39
'o', 'p', 'q', 'r', 's', 't', 'u', 'v', // 40 to 47
'w', 'x', 'y', 'z', '0', '1', '2', '3', // 48 to 55
'4', '5', '6', '7', '8', '9', '+', '/' }; // 56 to 63
//////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////
public static String encode ( String s )
//////////////////////////////////////////////////////////////////////
{
return encode ( s.getBytes ( ) );
}
public static String encode ( byte [ ] octetString )
//////////////////////////////////////////////////////////////////////
{
int bits24;
int bits6;
char [ ] out
= new char [ ( ( octetString.length - 1 ) / 3 + 1 ) * 4 ];
int outIndex = 0;
int i = 0;
while ( ( i + 3 ) <= octetString.length )
{
// store the octets
bits24 = ( octetString [ i++ ] & 0xFF ) << 16;
bits24 |= ( octetString [ i++ ] & 0xFF ) << 8;
bits24 |= ( octetString [ i++ ] & 0xFF ) << 0;
bits6 = ( bits24 & 0x00FC0000 ) >> 18;
out [ outIndex++ ] = alphabet [ bits6 ];
bits6 = ( bits24 & 0x0003F000 ) >> 12;
out [ outIndex++ ] = alphabet [ bits6 ];
bits6 = ( bits24 & 0x00000FC0 ) >> 6;
out [ outIndex++ ] = alphabet [ bits6 ];
bits6 = ( bits24 & 0x0000003F );
out [ outIndex++ ] = alphabet [ bits6 ];
}
if ( octetString.length - i == 2 )
{
// store the octets
bits24 = ( octetString [ i ] & 0xFF ) << 16;
bits24 |= ( octetString [ i + 1 ] & 0xFF ) << 8;
bits6 = ( bits24 & 0x00FC0000 ) >> 18;
out [ outIndex++ ] = alphabet [ bits6 ];
bits6 = ( bits24 & 0x0003F000 ) >> 12;
out [ outIndex++ ] = alphabet [ bits6 ];
bits6 = ( bits24 & 0x00000FC0 ) >> 6;
out [ outIndex++ ] = alphabet [ bits6 ];
// padding
out [ outIndex++ ] = '=';
}
else if ( octetString.length - i == 1 )
{
// store the octets
bits24 = ( octetString [ i ] & 0xFF ) << 16;
bits6 = ( bits24 & 0x00FC0000 ) >> 18;
out [ outIndex++ ] = alphabet [ bits6 ];
bits6 = ( bits24 & 0x0003F000 ) >> 12;
out [ outIndex++ ] = alphabet [ bits6 ];
// padding
out [ outIndex++ ] = '=';
out [ outIndex++ ] = '=';
}
return new String ( out );
}
----
############################
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