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package sun.misc;
import java.io.OutputStream;
import java.io.PushbackInputStream;
import java.io.PrintStream;
This class implements a BASE64 Character decoder as specified in RFC1521.
This RFC is part of the MIME specification which is published by the
Internet Engineering Task Force (IETF). Unlike some other encoding
schemes there is nothing in this encoding that tells the decoder
where a buffer starts or stops, so to use it you will need to isolate
your encoded data into a single chunk and then feed them this decoder.
The simplest way to do that is to read all of the encoded data into a
string and then use:
byte mydata[];
BASE64Decoder base64 = new BASE64Decoder();
mydata = base64.decodeBuffer(bufferString);
This will decode the String in bufferString and give you an array
of bytes in the array myData.
On errors, this class throws a CEFormatException with the following detail
strings:
"BASE64Decoder: Not enough bytes for an atom."
Author: Chuck McManis See Also:
/**
* This class implements a BASE64 Character decoder as specified in RFC1521.
*
* This RFC is part of the MIME specification which is published by the
* Internet Engineering Task Force (IETF). Unlike some other encoding
* schemes there is nothing in this encoding that tells the decoder
* where a buffer starts or stops, so to use it you will need to isolate
* your encoded data into a single chunk and then feed them this decoder.
* The simplest way to do that is to read all of the encoded data into a
* string and then use:
* <pre>
* byte mydata[];
* BASE64Decoder base64 = new BASE64Decoder();
*
* mydata = base64.decodeBuffer(bufferString);
* </pre>
* This will decode the String in <i>bufferString</i> and give you an array
* of bytes in the array <i>myData</i>.
*
* On errors, this class throws a CEFormatException with the following detail
* strings:
* <pre>
* "BASE64Decoder: Not enough bytes for an atom."
* </pre>
*
* @author Chuck McManis
* @see CharacterEncoder
* @see BASE64Decoder
*/
public class BASE64Decoder extends CharacterDecoder {
This class has 4 bytes per atom /** This class has 4 bytes per atom */
protected int bytesPerAtom() {
return (4);
}
Any multiple of 4 will do, 72 might be common /** Any multiple of 4 will do, 72 might be common */
protected int bytesPerLine() {
return (72);
}
This character array provides the character to value map
based on RFC1521.
/**
* This character array provides the character to value map
* based on RFC1521.
*/
private final static char pem_array[] = {
// 0 1 2 3 4 5 6 7
'A','B','C','D','E','F','G','H', // 0
'I','J','K','L','M','N','O','P', // 1
'Q','R','S','T','U','V','W','X', // 2
'Y','Z','a','b','c','d','e','f', // 3
'g','h','i','j','k','l','m','n', // 4
'o','p','q','r','s','t','u','v', // 5
'w','x','y','z','0','1','2','3', // 6
'4','5','6','7','8','9','+','/' // 7
};
private final static byte pem_convert_array[] = new byte[256];
static {
for (int i = 0; i < 255; i++) {
pem_convert_array[i] = -1;
}
for (int i = 0; i < pem_array.length; i++) {
pem_convert_array[pem_array[i]] = (byte) i;
}
}
byte decode_buffer[] = new byte[4];
Decode one BASE64 atom into 1, 2, or 3 bytes of data.
/**
* Decode one BASE64 atom into 1, 2, or 3 bytes of data.
*/
@SuppressWarnings("fallthrough")
protected void decodeAtom(PushbackInputStream inStream, OutputStream outStream, int rem)
throws java.io.IOException
{
int i;
byte a = -1, b = -1, c = -1, d = -1;
if (rem < 2) {
throw new CEFormatException("BASE64Decoder: Not enough bytes for an atom.");
}
do {
i = inStream.read();
if (i == -1) {
throw new CEStreamExhausted();
}
} while (i == '\n' || i == '\r');
decode_buffer[0] = (byte) i;
i = readFully(inStream, decode_buffer, 1, rem-1);
if (i == -1) {
throw new CEStreamExhausted();
}
if (rem > 3 && decode_buffer[3] == '=') {
rem = 3;
}
if (rem > 2 && decode_buffer[2] == '=') {
rem = 2;
}
switch (rem) {
case 4:
d = pem_convert_array[decode_buffer[3] & 0xff];
// NOBREAK
case 3:
c = pem_convert_array[decode_buffer[2] & 0xff];
// NOBREAK
case 2:
b = pem_convert_array[decode_buffer[1] & 0xff];
a = pem_convert_array[decode_buffer[0] & 0xff];
break;
}
switch (rem) {
case 2:
outStream.write( (byte)(((a << 2) & 0xfc) | ((b >>> 4) & 3)) );
break;
case 3:
outStream.write( (byte) (((a << 2) & 0xfc) | ((b >>> 4) & 3)) );
outStream.write( (byte) (((b << 4) & 0xf0) | ((c >>> 2) & 0xf)) );
break;
case 4:
outStream.write( (byte) (((a << 2) & 0xfc) | ((b >>> 4) & 3)) );
outStream.write( (byte) (((b << 4) & 0xf0) | ((c >>> 2) & 0xf)) );
outStream.write( (byte) (((c << 6) & 0xc0) | (d & 0x3f)) );
break;
}
return;
}
}