/*
* Base64 encoding and decoding.
* Copyright (C) 2001-2004 Stephen Ostermiller
* http://ostermiller.org/contact.pl?regarding=Java+Utilities
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* See COPYING.TXT for details.
*/
package org.signalml.util;
import java.io.*;
import java.text.MessageFormat;
/**
* Implements Base64 encoding and decoding as defined by RFC 2045: "Multipurpose Internet
* Mail Extensions (MIME) Part One: Format of Internet Message Bodies" page 23.
* More information about this class is available from <a target="_top" href=
* "http://ostermiller.org/utils/Base64.html">ostermiller.org</a>.
*
* <blockquote>
* <p>The Base64 Content-Transfer-Encoding is designed to represent
* arbitrary sequences of octets in a form that need not be humanly
* readable. The encoding and decoding algorithms are simple, but the
* encoded data are consistently only about 33 percent larger than the
* unencoded data. This encoding is virtually identical to the one used
* in Privacy Enhanced Mail (PEM) applications, as defined in RFC 1421.</p>
*
* <p>A 65-character subset of US-ASCII is used, enabling 6 bits to be
* represented per printable character. (The extra 65th character, "=",
* is used to signify a special processing function.)</p>
*
* <p>NOTE: This subset has the important property that it is represented
* identically in all versions of ISO 646, including US-ASCII, and all
* characters in the subset are also represented identically in all
* versions of EBCDIC. Other popular encodings, such as the encoding
* used by the uuencode utility, Macintosh binhex 4.0 [RFC-1741], and
* the base85 encoding specified as part of Level 2 PostScript, do no
* share these properties, and thus do not fulfill the portability
* requirements a binary transport encoding for mail must meet.</p>
*
* <p>The encoding process represents 24-bit groups of input bits as output
* strings of 4 encoded characters. Proceeding from left to right, a
* 24-bit input group is formed by concatenating 3 8bit input groups.
* These 24 bits are then treated as 4 concatenated 6-bit groups, each
* of which is translated into a single digit in the base64 alphabet.
* When encoding a bit stream via the base64 encoding, the bit stream
* must be presumed to be ordered with the most-significant-bit first.
* That is, the first bit in the stream will be the high-order bit in
* the first 8bit byte, and the eighth bit will be the low-order bit in
* the first 8bit byte, and so on.</p>
*
* <p>Each 6-bit group is used as an index into an array of 64 printable
* characters. The character referenced by the index is placed in the
* output string. These characters, identified in Table 1, below, are
* selected so as to be universally representable, and the set excludes
* characters with particular significance to SMTP (e.g., ".", CR, LF)
* and to the multipart boundary delimiters defined in RFC 2046 (e.g.,
* "-").</p>
* <pre>
* Table 1: The Base64 Alphabet
*
* Value Encoding Value Encoding Value Encoding Value Encoding
* 0 A 17 R 34 i 51 z
* 1 B 18 S 35 j 52 0
* 2 C 19 T 36 k 53 1
* 3 D 20 U 37 l 54 2
* 4 E 21 V 38 m 55 3
* 5 F 22 W 39 n 56 4
* 6 G 23 X 40 o 57 5
* 7 H 24 Y 41 p 58 6
* 8 I 25 Z 42 q 59 7
* 9 J 26 a 43 r 60 8
* 10 K 27 b 44 s 61 9
* 11 L 28 c 45 t 62 +
* 12 M 29 d 46 u 63 /
* 13 N 30 e 47 v
* 14 O 31 f 48 w (pad) =
* 15 P 32 g 49 x
* 16 Q 33 h 50 y
* </pre>
* <p>The encoded output stream must be represented in lines of no more
* than 76 characters each. All line breaks or other characters no
* found in Table 1 must be ignored by decoding software. In base64
* data, characters other than those in Table 1, line breaks, and other
* white space probably indicate a transmission error, about which a
* warning message or even a message rejection might be appropriate
* under some circumstances.</p>
*
* <p>Special processing is performed if fewer than 24 bits are available
* at the end of the data being encoded. A full encoding quantum is
* always completed at the end of a body. When fewer than 24 input bits
* are available in an input group, zero bits are added (on the right)
* to form an integral number of 6-bit groups. Padding at the end of
* the data is performed using the "=" character. Since all base64
* input is an integral number of octets, only the following cases can
* arise: (1) the final quantum of encoding input is an integral
* multiple of 24 bits; here, the final unit of encoded output will be
* an integral multiple of 4 characters with no "=" padding, (2) the
* final quantum of encoding input is exactly 8 bits; here, the final
* unit of encoded output will be two characters followed by two "="
* padding characters, or (3) the final quantum of encoding input is
* exactly 16 bits; here, the final unit of encoded output will be three
* characters followed by one "=" padding character.</p>
*
* <p>Because it is used only for padding at the end of the data, the
* occurrence of any "=" characters may be taken as evidence that the
* end of the data has been reached (without truncation in transit). No
* such assurance is possible, however, when the number of octets
* transmitted was a multiple of three and no "=" characters are
* present.</p>
*
* <p>Any characters outside of the base64 alphabet are to be ignored in
* base64-encoded data.</p>
*
* <p>Care must be taken to use the proper octets for line breaks if base64
* encoding is applied directly to text material that has not been
* converted to canonical form. In particular, text line breaks must be
* converted into CRLF sequences prior to base64 encoding. The
* important thing to note is that this may be done directly by the
* encoder rather than in a prior canonicalization step in some
* implementations.</p>
*
* <p>NOTE: There is no need to worry about quoting potential boundary
* delimiters within base64-encoded bodies within multipart entities
* because no hyphen characters are used in the base64 encoding.</p>
* </blockquote>
*
* @author Stephen Ostermiller http://ostermiller.org/contact.pl?regarding=Java+Utilities
* @since ostermillerutils 1.00.00
*/
public class Base64 {
/**
* Symbol that represents the end of an input stream
*
* @since ostermillerutils 1.00.00
*/
private static final int END_OF_INPUT = -1;
/**
* A character that is not a valid base 64 character.
*
* @since ostermillerutils 1.00.00
*/
private static final int NON_BASE_64 = -1;
/**
* A character that is not a valid base 64 character.
*
* @since ostermillerutils 1.00.00
*/
private static final int NON_BASE_64_WHITESPACE = -2;
/**
* A character that is not a valid base 64 character.
*
* @since ostermillerutils 1.00.00
*/
private static final int NON_BASE_64_PADDING = -3;
/**
* This class need not be instantiated, all methods are static.
*
* @since ostermillerutils 1.00.00
*/
private Base64() {
}
/**
* Table of the sixty-four characters that are used as
* the Base64 alphabet: [A-Za-z0-9+/]
*
* @since ostermillerutils 1.00.00
*/
protected static final byte[] base64Chars = {
'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','+','/',
};
/**
* Reverse lookup table for the Base64 alphabet.
* reversebase64Chars[byte] gives n for the nth Base64
* character or negative if a character is not a Base64 character.
*
* @since ostermillerutils 1.00.00
*/
protected static final byte[] reverseBase64Chars = new byte[0x100];
static {
// Fill in NON_BASE_64 for all characters to start with
for (int i=0; i<reverseBase64Chars.length; i++) {
reverseBase64Chars[i] = NON_BASE_64;
}
// For characters that are base64Chars, adjust
// the reverse lookup table.
for (byte i=0; i < base64Chars.length; i++) {
reverseBase64Chars[base64Chars[i]] = i;
}
reverseBase64Chars[' '] = NON_BASE_64_WHITESPACE;
reverseBase64Chars['\n'] = NON_BASE_64_WHITESPACE;
reverseBase64Chars['\r'] = NON_BASE_64_WHITESPACE;
reverseBase64Chars['\t'] = NON_BASE_64_WHITESPACE;
reverseBase64Chars['\f'] = NON_BASE_64_WHITESPACE;
reverseBase64Chars['='] = NON_BASE_64_PADDING;
}
/**
* Version number of this program
*
* @since ostermillerutils 1.00.00
*/
public static final String version = "1.2";
/**
* Encode a String in Base64.
* The String is converted to and from bytes according to the platform's
* default character encoding.
* No line breaks or other white space are inserted into the encoded data.
*
* @param string The data to encode.
* @return An encoded String.
*
* @since ostermillerutils 1.00.00
*/
public static String encode(String string) {
return new String(encode(string.getBytes()));
}
/**
* Encode a String in Base64.
* No line breaks or other white space are inserted into the encoded data.
*
* @param string The data to encode.
* @param enc Character encoding to use when converting to and from bytes.
* @throws UnsupportedEncodingException if the character encoding specified is not supported.
* @return An encoded String.
*
* @since ostermillerutils 1.00.00
*/
public static String encode(String string, String enc) throws UnsupportedEncodingException {
return new String(encode(string.getBytes(enc)), enc);
}
/**
* Encode bytes in Base64.
* No line breaks or other white space are inserted into the encoded data.
*
* @param bytes The data to encode.
* @return String with Base64 encoded data.
*
* @since ostermillerutils 1.04.00
*/
public static String encodeToString(byte[] bytes) {
return encodeToString(bytes, false);
}
/**
* Encode bytes in Base64.
*
* @param bytes The data to encode.
* @param lineBreaks Whether to insert line breaks every 76 characters in the output.
* @return String with Base64 encoded data.
*
* @since ostermillerutils 1.04.00
*/
public static String encodeToString(byte[] bytes, boolean lineBreaks) {
try {
return new String(encode(bytes, lineBreaks), "ASCII");
} catch (UnsupportedEncodingException iex) {
// ASCII should be supported
throw new RuntimeException(iex);
}
}
/**
* Encode bytes in Base64.
* No line breaks or other white space are inserted into the encoded data.
*
* @param bytes The data to encode.
* @return Encoded bytes.
*
* @since ostermillerutils 1.00.00
*/
public static byte[] encode(byte[] bytes) {
return encode(bytes, false);
}
/**
* Encode bytes in Base64.
*
* @param bytes The data to encode.
* @param lineBreaks Whether to insert line breaks every 76 characters in the output.
* @return Encoded bytes.
*
* @since ostermillerutils 1.04.00
*/
public static byte[] encode(byte[] bytes, boolean lineBreaks) {
ByteArrayInputStream in = new ByteArrayInputStream(bytes);
// calculate the length of the resulting output.
// in general it will be 4/3 the size of the input
// but the input length must be divisible by three.
// If it isn't the next largest size that is divisible
// by three is used.
int mod;
int length = bytes.length;
if ((mod = length % 3) != 0) {
length += 3 - mod;
}
length = length * 4 / 3;
ByteArrayOutputStream out = new ByteArrayOutputStream(length);
try {
encode(in, out, lineBreaks);
} catch (IOException x) {
// This can't happen.
// The input and output streams were constructed
// on memory structures that don't actually use IO.
throw new RuntimeException(x);
}
return out.toByteArray();
}
/**
* Encode data from the InputStream to the OutputStream in Base64.
* Line breaks are inserted every 76 characters in the output.
*
* @param in Stream from which to read data that needs to be encoded.
* @param out Stream to which to write encoded data.
* @throws IOException if there is a problem reading or writing.
*
* @since ostermillerutils 1.00.00
*/
public static void encode(InputStream in, OutputStream out) throws IOException {
encode(in, out, true);
}
/**
* Encode data from the InputStream to the OutputStream in Base64.
*
* @param in Stream from which to read data that needs to be encoded.
* @param out Stream to which to write encoded data.
* @param lineBreaks Whether to insert line breaks every 76 characters in the output.
* @throws IOException if there is a problem reading or writing.
*
* @since ostermillerutils 1.00.00
*/
public static void encode(InputStream in, OutputStream out, boolean lineBreaks) throws IOException {
// Base64 encoding converts three bytes of input to
// four bytes of output
int[] inBuffer = new int[3];
int lineCount = 0;
boolean done = false;
while (!done && (inBuffer[0] = in.read()) != END_OF_INPUT) {
// Fill the buffer
inBuffer[1] = in.read();
inBuffer[2] = in.read();
// Calculate the out Buffer
// The first byte of our in buffer will always be valid
// but we must check to make sure the other two bytes
// are not END_OF_INPUT before using them.
// The basic idea is that the three bytes get split into
// four bytes along these lines:
// [AAAAAABB] [BBBBCCCC] [CCDDDDDD]
// [xxAAAAAA] [xxBBBBBB] [xxCCCCCC] [xxDDDDDD]
// bytes are considered to be zero when absent.
// the four bytes are then mapped to common ASCII symbols
// A's: first six bits of first byte
out.write(base64Chars[ inBuffer[0] >> 2 ]);
if (inBuffer[1] != END_OF_INPUT) {
// B's: last two bits of first byte, first four bits of second byte
out.write(base64Chars [((inBuffer[0] << 4) & 0x30) | (inBuffer[1] >> 4)]);
if (inBuffer[2] != END_OF_INPUT) {
// C's: last four bits of second byte, first two bits of third byte
out.write(base64Chars [((inBuffer[1] << 2) & 0x3c) | (inBuffer[2] >> 6)]);
// D's: last six bits of third byte
out.write(base64Chars [inBuffer[2] & 0x3F]);
} else {
// C's: last four bits of second byte
out.write(base64Chars [((inBuffer[1] << 2) & 0x3c)]);
// an equals sign for a character that is not a Base64 character
out.write('=');
done = true;
}
} else {
// B's: last two bits of first byte
out.write(base64Chars [((inBuffer[0] << 4) & 0x30)]);
// an equal signs for characters that is not a Base64 characters
out.write('=');
out.write('=');
done = true;
}
lineCount += 4;
if (lineBreaks && lineCount >= 76) {
out.write('\n');
lineCount = 0;
}
}
if (lineBreaks && lineCount >= 1) {
out.write('\n');
lineCount = 0;
}
out.flush();
}
/**
* Decode a Base64 encoded String.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
* The String is converted to and from bytes according to the platform's
* default character encoding.
*
* @param string The data to decode.
* @return A decoded String.
*
* @since ostermillerutils 1.00.00
*/
public static String decode(String string) {
return new String(decode(string.getBytes()));
}
/**
* Decode a Base64 encoded String.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param string The data to decode.
* @param enc Character encoding to use when converting to and from bytes.
* @throws UnsupportedEncodingException if the character encoding specified is not supported.
* @return A decoded String.
*
* @since ostermillerutils 1.00.00
*/
public static String decode(String string, String enc) throws UnsupportedEncodingException {
return new String(decode(string.getBytes(enc)), enc);
}
/**
* Decode a Base64 encoded String.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param string The data to decode.
* @param encIn Character encoding to use when converting input to bytes (should not matter because Base64 data is designed to survive most character encodings)
* @param encOut Character encoding to use when converting decoded bytes to output.
* @throws UnsupportedEncodingException if the character encoding specified is not supported.
* @return A decoded String.
*
* @since ostermillerutils 1.00.00
*/
public static String decode(String string, String encIn, String encOut) throws UnsupportedEncodingException {
return new String(decode(string.getBytes(encIn)), encOut);
}
/**
* Decode a Base64 encoded String.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
* The String is converted to and from bytes according to the platform's
* default character encoding.
*
* @param string The data to decode.
* @return A decoded String.
*
* @since ostermillerutils 1.02.16
*/
public static String decodeToString(String string) {
return new String(decode(string.getBytes()));
}
/**
* Decode a Base64 encoded String.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param string The data to decode.
* @param enc Character encoding to use when converting to and from bytes.
* @throws UnsupportedEncodingException if the character encoding specified is not supported.
* @return A decoded String.
*
* @since ostermillerutils 1.02.16
*/
public static String decodeToString(String string, String enc) throws UnsupportedEncodingException {
return new String(decode(string.getBytes(enc)), enc);
}
/**
* Decode a Base64 encoded String.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param string The data to decode.
* @param encIn Character encoding to use when converting input to bytes (should not matter because Base64 data is designed to survive most character encodings)
* @param encOut Character encoding to use when converting decoded bytes to output.
* @throws UnsupportedEncodingException if the character encoding specified is not supported.
* @return A decoded String.
*
* @since ostermillerutils 1.02.16
*/
public static String decodeToString(String string, String encIn, String encOut) throws UnsupportedEncodingException {
return new String(decode(string.getBytes(encIn)), encOut);
}
/**
* Decode a Base64 encoded String to an OutputStream.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
* The String is converted from bytes according to the platform's
* default character encoding.
*
* @param string The data to decode.
* @param out Stream to which to write decoded data.
* @throws IOException if an IO error occurs.
*
* @since ostermillerutils 1.02.16
*/
public static void decodeToStream(String string, OutputStream out) throws IOException {
decode(new ByteArrayInputStream(string.getBytes()), out);
}
/**
* Decode a Base64 encoded String to an OutputStream.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param string The data to decode.
* @param enc Character encoding to use when converting to and from bytes.
* @param out Stream to which to write decoded data.
* @throws UnsupportedEncodingException if the character encoding specified is not supported.
* @throws IOException if an IO error occurs.
*
* @since ostermillerutils 1.02.16
*/
public static void decodeToStream(String string, String enc, OutputStream out) throws UnsupportedEncodingException, IOException {
decode(new ByteArrayInputStream(string.getBytes(enc)), out);
}
/**
* Decode a Base64 encoded String.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
* The String is converted from bytes according to the platform's
* default character encoding.
*
* @param string The data to decode.
* @return decoded data.
*
* @since ostermillerutils 1.02.16
*/
public static byte[] decodeToBytes(String string) {
return decode(string.getBytes());
}
/**
* Decode a Base64 encoded String.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param string The data to decode.
* @param enc Character encoding to use when converting from bytes.
* @throws UnsupportedEncodingException if the character encoding specified is not supported.
* @return decoded data.
*
* @since ostermillerutils 1.02.16
*/
public static byte[] decodeToBytes(String string, String enc) throws UnsupportedEncodingException {
return decode(string.getBytes(enc));
}
/**
* Decode Base64 encoded bytes.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
* The String is converted to bytes according to the platform's
* default character encoding.
*
* @param bytes The data to decode.
* @return A decoded String.
*
* @since ostermillerutils 1.02.16
*/
public static String decodeToString(byte[] bytes) {
return new String(decode(bytes));
}
/**
* Decode Base64 encoded bytes.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param bytes The data to decode.
* @param enc Character encoding to use when converting to and from bytes.
* @throws UnsupportedEncodingException if the character encoding specified is not supported.
* @return A decoded String.
*
* @since ostermillerutils 1.02.16
*/
public static String decodeToString(byte[] bytes, String enc) throws UnsupportedEncodingException {
return new String(decode(bytes), enc);
}
/**
* Decode Base64 encoded bytes.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param bytes The data to decode.
* @return Decoded bytes.
*
* @since ostermillerutils 1.02.16
*/
public static byte[] decodeToBytes(byte[] bytes) {
return decode(bytes);
}
/**
* Decode Base64 encoded bytes.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param bytes The data to decode.
* @return Decoded bytes.
*
* @since ostermillerutils 1.00.00
*/
public static byte[] decode(byte[] bytes) {
ByteArrayInputStream in = new ByteArrayInputStream(bytes);
// calculate the length of the resulting output.
// in general it will be at most 3/4 the size of the input
// but the input length must be divisible by four.
// If it isn't the next largest size that is divisible
// by four is used.
int mod;
int length = bytes.length;
if ((mod = length % 4) != 0) {
length += 4 - mod;
}
length = length * 3 / 4;
ByteArrayOutputStream out = new ByteArrayOutputStream(length);
try {
decode(in, out, false);
} catch (IOException x) {
// This can't happen.
// The input and output streams were constructed
// on memory structures that don't actually use IO.
throw new RuntimeException(x);
}
return out.toByteArray();
}
/**
* Decode Base64 encoded bytes to the an OutputStream.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param bytes The data to decode.
* @param out Stream to which to write decoded data.
* @throws IOException if an IO error occurs.
*
* @since ostermillerutils 1.00.00
*/
public static void decode(byte[] bytes, OutputStream out) throws IOException {
ByteArrayInputStream in = new ByteArrayInputStream(bytes);
decode(in, out, false);
}
/**
* Decode Base64 encoded bytes to the an OutputStream.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param bytes The data to decode.
* @param out Stream to which to write decoded data.
* @throws IOException if an IO error occurs.
*
* @since ostermillerutils 1.02.16
*/
public static void decodeToStream(byte[] bytes, OutputStream out) throws IOException {
ByteArrayInputStream in = new ByteArrayInputStream(bytes);
decode(in, out, false);
}
/**
* Reads the next (decoded) Base64 character from the input stream.
* Non Base64 characters are skipped.
*
* @param in Stream from which bytes are read.
* @param throwExceptions Throw an exception if an unexpected character is encountered.
* @return the next Base64 character from the stream or -1 if there are no more Base64 characters on the stream.
* @throws IOException if an IO Error occurs.
* @throws Base64DecodingException if unexpected data is encountered when throwExceptions is specified.
*
* @since ostermillerutils 1.00.00
*/
private static final int readBase64(InputStream in, boolean throwExceptions) throws IOException {
int read;
int numPadding = 0;
do {
read = in.read();
if (read == END_OF_INPUT) return END_OF_INPUT;
read = reverseBase64Chars[(byte)read];
if (throwExceptions && (read == NON_BASE_64 || (numPadding > 0 && read > NON_BASE_64))) {
throw new Base64DecodingException(
MessageFormat.format(
"unexpectedchar",
(Object[])new String[] {
"'" + (char)read + "' (0x" + Integer.toHexString(read) + ")"
}
),
(char)read
);
}
if (read == NON_BASE_64_PADDING) {
numPadding++;
}
} while (read <= NON_BASE_64);
return read;
}
/**
* Decode Base64 encoded data from the InputStream to a byte array.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param in Stream from which to read data that needs to be decoded.
* @return decoded data.
* @throws IOException if an IO error occurs.
*
* @since ostermillerutils 1.00.00
*/
public static byte[] decodeToBytes(InputStream in) throws IOException {
ByteArrayOutputStream out = new ByteArrayOutputStream();
decode(in, out, false);
return out.toByteArray();
}
/**
* Decode Base64 encoded data from the InputStream to a String.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
* Bytes are converted to characters in the output String according to the platform's
* default character encoding.
*
* @param in Stream from which to read data that needs to be decoded.
* @return decoded data.
* @throws IOException if an IO error occurs.
*
* @since ostermillerutils 1.02.16
*/
public static String decodeToString(InputStream in) throws IOException {
return new String(decodeToBytes(in));
}
/**
* Decode Base64 encoded data from the InputStream to a String.
* Characters that are not part of the Base64 alphabet are ignored
* in the input.
*
* @param in Stream from which to read data that needs to be decoded.
* @param enc Character encoding to use when converting bytes to characters.
* @return decoded data.
* @throws IOException if an IO error occurs.Throws:
* @throws UnsupportedEncodingException if the character encoding specified is not supported.
*
* @since ostermillerutils 1.02.16
*/
public static String decodeToString(InputStream in, String enc) throws IOException {
return new String(decodeToBytes(in), enc);
}
/**
* Decode Base64 encoded data from the InputStream to the OutputStream.
* Characters in the Base64 alphabet, white space and equals sign are
* expected to be in urlencoded data. The presence of other characters
* could be a sign that the data is corrupted.
*
* @param in Stream from which to read data that needs to be decoded.
* @param out Stream to which to write decoded data.
* @throws IOException if an IO error occurs.
* @throws Base64DecodingException if unexpected data is encountered.
*
* @since ostermillerutils 1.00.00
*/
public static void decode(InputStream in, OutputStream out) throws IOException {
decode(in, out, true);
}
/**
* Decode Base64 encoded data from the InputStream to the OutputStream.
* Characters in the Base64 alphabet, white space and equals sign are
* expected to be in urlencoded data. The presence of other characters
* could be a sign that the data is corrupted.
*
* @param in Stream from which to read data that needs to be decoded.
* @param out Stream to which to write decoded data.
* @param throwExceptions Whether to throw exceptions when unexpected data is encountered.
* @throws IOException if an IO error occurs.
* @throws Base64DecodingException if unexpected data is encountered when throwExceptions is specified.
*
* @since ostermillerutils 1.00.00
*/
public static void decode(InputStream in, OutputStream out, boolean throwExceptions) throws IOException {
// Base64 decoding converts four bytes of input to three bytes of output
int[] inBuffer = new int[4];
// read bytes unmapping them from their ASCII encoding in the process
// we must read at least two bytes to be able to output anything
boolean done = false;
while (!done && (inBuffer[0] = readBase64(in, throwExceptions)) != END_OF_INPUT
&& (inBuffer[1] = readBase64(in, throwExceptions)) != END_OF_INPUT) {
// Fill the buffer
inBuffer[2] = readBase64(in, throwExceptions);
inBuffer[3] = readBase64(in, throwExceptions);
// Calculate the output
// The first two bytes of our in buffer will always be valid
// but we must check to make sure the other two bytes
// are not END_OF_INPUT before using them.
// The basic idea is that the four bytes will get reconstituted
// into three bytes along these lines:
// [xxAAAAAA] [xxBBBBBB] [xxCCCCCC] [xxDDDDDD]
// [AAAAAABB] [BBBBCCCC] [CCDDDDDD]
// bytes are considered to be zero when absent.
// six A and two B
out.write(inBuffer[0] << 2 | inBuffer[1] >> 4);
if (inBuffer[2] != END_OF_INPUT) {
// four B and four C
out.write(inBuffer[1] << 4 | inBuffer[2] >> 2);
if (inBuffer[3] != END_OF_INPUT) {
// two C and six D
out.write(inBuffer[2] << 6 | inBuffer[3]);
} else {
done = true;
}
} else {
done = true;
}
}
out.flush();
}
/**
* Determines if the byte array is in base64 format.
* <p>
* Data will be considered to be in base64 format if it contains
* only base64 characters and whitespace with equals sign padding
* on the end so that the number of base64 characters is divisible
* by four.
* <p>
* It is possible for data to be in base64 format but for it to not
* meet these stringent requirements. It is also possible for data
* to meet these requirements even though decoding it would not make
* any sense. This method should be used as a guide but it is not
* authoritative because of the possibility of these false positives
* and false negatives.
* <p>
* Additionally, extra data such as headers or footers may throw
* this method off the scent and cause it to return false.
*
* @param bytes data that could be in base64 format.
*
* @since ostermillerutils 1.00.00
*/
public static boolean isBase64(byte[] bytes) {
try {
return isBase64(new ByteArrayInputStream(bytes));
} catch (IOException x) {
// This can't happen.
// The input and output streams were constructed
// on memory structures that don't actually use IO.
return false;
}
}
/**
* Determines if the String is in base64 format.
* The String is converted to and from bytes according to the platform's
* default character encoding.
* <p>
* Data will be considered to be in base64 format if it contains
* only base64 characters and whitespace with equals sign padding
* on the end so that the number of base64 characters is divisible
* by four.
* <p>
* It is possible for data to be in base64 format but for it to not
* meet these stringent requirements. It is also possible for data
* to meet these requirements even though decoding it would not make
* any sense. This method should be used as a guide but it is not
* authoritative because of the possibility of these false positives
* and false negatives.
* <p>
* Additionally, extra data such as headers or footers may throw
* this method off the scent and cause it to return false.
*
* @param string String that may be in base64 format.
* @return Best guess as to whether the data is in base64 format.
*
* @since ostermillerutils 1.00.00
*/
public static boolean isBase64(String string) {
return isBase64(string.getBytes());
}
/**
* Determines if the String is in base64 format.
* <p>
* Data will be considered to be in base64 format if it contains
* only base64 characters and whitespace with equals sign padding
* on the end so that the number of base64 characters is divisible
* by four.
* <p>
* It is possible for data to be in base64 format but for it to not
* meet these stringent requirements. It is also possible for data
* to meet these requirements even though decoding it would not make
* any sense. This method should be used as a guide but it is not
* authoritative because of the possibility of these false positives
* and false negatives.
* <p>
* Additionally, extra data such as headers or footers may throw
* this method off the scent and cause it to return false.
*
* @param string String that may be in base64 format.
* @param enc Character encoding to use when converting to bytes.
* @return Best guess as to whether the data is in base64 format.
* @throws UnsupportedEncodingException if the character encoding specified is not supported.
*/
public static boolean isBase64(String string, String enc) throws UnsupportedEncodingException {
return isBase64(string.getBytes(enc));
}
/**
* Determines if the File is in base64 format.
* <p>
* Data will be considered to be in base64 format if it contains
* only base64 characters and whitespace with equals sign padding
* on the end so that the number of base64 characters is divisible
* by four.
* <p>
* It is possible for data to be in base64 format but for it to not
* meet these stringent requirements. It is also possible for data
* to meet these requirements even though decoding it would not make
* any sense. This method should be used as a guide but it is not
* authoritative because of the possibility of these false positives
* and false negatives.
* <p>
* Additionally, extra data such as headers or footers may throw
* this method off the scent and cause it to return false.
*
* @param fIn File that may be in base64 format.
* @return Best guess as to whether the data is in base64 format.
* @throws IOException if an IO error occurs.
*
* @since ostermillerutils 1.00.00
*/
public static boolean isBase64(File fIn) throws IOException {
return isBase64(new BufferedInputStream(new FileInputStream(fIn)));
}
/**
* Reads data from the stream and determines if it is
* in base64 format.
* <p>
* Data will be considered to be in base64 format if it contains
* only base64 characters and whitespace with equals sign padding
* on the end so that the number of base64 characters is divisible
* by four.
* <p>
* It is possible for data to be in base64 format but for it to not
* meet these stringent requirements. It is also possible for data
* to meet these requirements even though decoding it would not make
* any sense. This method should be used as a guide but it is not
* authoritative because of the possibility of these false positives
* and false negatives.
* <p>
* Additionally, extra data such as headers or footers may throw
* this method off the scent and cause it to return false.
*
* @param in Stream from which to read data to be tested.
* @return Best guess as to whether the data is in base64 format.
* @throws IOException if an IO error occurs.
*
* @since ostermillerutils 1.00.00
*/
public static boolean isBase64(InputStream in) throws IOException {
long numBase64Chars = 0;
int numPadding = 0;
int read;
while ((read = in.read()) != -1) {
read = reverseBase64Chars[read];
if (read == NON_BASE_64) {
return false;
} else if (read == NON_BASE_64_WHITESPACE) {
} else if (read == NON_BASE_64_PADDING) {
numPadding++;
numBase64Chars++;
} else if (numPadding > 0) {
return false;
} else {
numBase64Chars++;
}
}
if (numBase64Chars == 0) return false;
if (numBase64Chars % 4 != 0) return false;
return true;
}
}