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package sun.misc;

import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.IOException;

This class implements a Berkeley uu character encoder. This encoder was made famous by uuencode program. The basic character coding is algorithmic, taking 6 bits of binary data and adding it to an ASCII ' ' (space) character. This converts these six bits into a printable representation. Note that it depends on the ASCII character encoding standard for english. Groups of three bytes are converted into 4 characters by treating the three bytes a four 6 bit groups, group 1 is byte 1's most significant six bits, group 2 is byte 1's least significant two bits plus byte 2's four most significant bits. etc. In this encoding, the buffer prefix is:
    begin [mode] [filename]
This is followed by one or more lines of the form:
     (len)(data)(data)(data) ...
where (len) is the number of bytes on this line. Note that groupings are always four characters, even if length is not a multiple of three bytes. When less than three characters are encoded, the values of the last remaining bytes is undefined and should be ignored. The last line of data in a uuencoded file is represented by a single space character. This is translated by the decoding engine to a line length of zero. This is immediately followed by a line which contains the word 'end[newline]'
Author: Chuck McManis
See Also:
/** * This class implements a Berkeley uu character encoder. This encoder * was made famous by uuencode program. * * The basic character coding is algorithmic, taking 6 bits of binary * data and adding it to an ASCII ' ' (space) character. This converts * these six bits into a printable representation. Note that it depends * on the ASCII character encoding standard for english. Groups of three * bytes are converted into 4 characters by treating the three bytes * a four 6 bit groups, group 1 is byte 1's most significant six bits, * group 2 is byte 1's least significant two bits plus byte 2's four * most significant bits. etc. * * In this encoding, the buffer prefix is: * <pre> * begin [mode] [filename] * </pre> * * This is followed by one or more lines of the form: * <pre> * (len)(data)(data)(data) ... * </pre> * where (len) is the number of bytes on this line. Note that groupings * are always four characters, even if length is not a multiple of three * bytes. When less than three characters are encoded, the values of the * last remaining bytes is undefined and should be ignored. * * The last line of data in a uuencoded file is represented by a single * space character. This is translated by the decoding engine to a line * length of zero. This is immediately followed by a line which contains * the word 'end[newline]' * * @author Chuck McManis * @see CharacterEncoder * @see UUDecoder */
public class UUEncoder extends CharacterEncoder {
This name is stored in the begin line.
/** * This name is stored in the begin line. */
private String bufferName;
Represents UNIX(tm) mode bits. Generally three octal digits representing read, write, and execute permission of the owner, group owner, and others. They should be interpreted as the bit groups: (owner) (group) (others) rwx rwx rwx (r = read, w = write, x = execute) By default these are set to 644 (UNIX rw-r--r-- permissions).
/** * Represents UNIX(tm) mode bits. Generally three octal digits representing * read, write, and execute permission of the owner, group owner, and * others. They should be interpreted as the bit groups: * (owner) (group) (others) * rwx rwx rwx (r = read, w = write, x = execute) * * By default these are set to 644 (UNIX rw-r--r-- permissions). */
private int mode;
Default - buffer begin line will be:
 begin 644 encoder.buf
/** * Default - buffer begin line will be: * <pre> * begin 644 encoder.buf * </pre> */
public UUEncoder() { bufferName = "encoder.buf"; mode = 644; }
Specifies a name for the encoded buffer, begin line will be:
 begin 644 [FNAME]
/** * Specifies a name for the encoded buffer, begin line will be: * <pre> * begin 644 [FNAME] * </pre> */
public UUEncoder(String fname) { bufferName = fname; mode = 644; }
Specifies a name and mode for the encoded buffer, begin line will be:
 begin [MODE] [FNAME]
/** * Specifies a name and mode for the encoded buffer, begin line will be: * <pre> * begin [MODE] [FNAME] * </pre> */
public UUEncoder(String fname, int newMode) { bufferName = fname; mode = newMode; }
number of bytes per atom in uuencoding is 3
/** number of bytes per atom in uuencoding is 3 */
protected int bytesPerAtom() { return (3); }
number of bytes per line in uuencoding is 45
/** number of bytes per line in uuencoding is 45 */
protected int bytesPerLine() { return (45); }
encodeAtom - take three bytes and encodes them into 4 characters If len is less than 3 then remaining bytes are filled with '1'. This insures that the last line won't end in spaces and potentiallly be truncated.
/** * encodeAtom - take three bytes and encodes them into 4 characters * If len is less than 3 then remaining bytes are filled with '1'. * This insures that the last line won't end in spaces and potentiallly * be truncated. */
protected void encodeAtom(OutputStream outStream, byte data[], int offset, int len) throws IOException { byte a, b = 1, c = 1; int c1, c2, c3, c4; a = data[offset]; if (len > 1) { b = data[offset+1]; } if (len > 2) { c = data[offset+2]; } c1 = (a >>> 2) & 0x3f; c2 = ((a << 4) & 0x30) | ((b >>> 4) & 0xf); c3 = ((b << 2) & 0x3c) | ((c >>> 6) & 0x3); c4 = c & 0x3f; outStream.write(c1 + ' '); outStream.write(c2 + ' '); outStream.write(c3 + ' '); outStream.write(c4 + ' '); return; }
Encode the line prefix which consists of the single character. The lenght is added to the value of ' ' (32 decimal) and printed.
/** * Encode the line prefix which consists of the single character. The * lenght is added to the value of ' ' (32 decimal) and printed. */
protected void encodeLinePrefix(OutputStream outStream, int length) throws IOException { outStream.write((length & 0x3f) + ' '); }
The line suffix for uuencoded files is simply a new line.
/** * The line suffix for uuencoded files is simply a new line. */
protected void encodeLineSuffix(OutputStream outStream) throws IOException { pStream.println(); }
encodeBufferPrefix writes the begin line to the output stream.
/** * encodeBufferPrefix writes the begin line to the output stream. */
protected void encodeBufferPrefix(OutputStream a) throws IOException { super.pStream = new PrintStream(a); super.pStream.print("begin "+mode+" "); if (bufferName != null) { super.pStream.println(bufferName); } else { super.pStream.println("encoder.bin"); } super.pStream.flush(); }
encodeBufferSuffix writes the single line containing space (' ') and the line containing the word 'end' to the output stream.
/** * encodeBufferSuffix writes the single line containing space (' ') and * the line containing the word 'end' to the output stream. */
protected void encodeBufferSuffix(OutputStream a) throws IOException { super.pStream.println(" \nend"); super.pStream.flush(); } }