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/* ========================================================================== *
* Copyright (C) 2004-2006, Pier Fumagalli . *
* *
* Unless required by applicable law or agreed to in writing, software *
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT *
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the *
* License for the specific language governing permissions and limitations *
* under the License. *
* *
* ========================================================================== */
package it.could.util.encoding;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;
/**
* An utility class providing various static methods dealing with
* encodings and {@link Encodable} objects..
*
* @author Pier Fumagalli
*/
public final class EncodingTools implements EncodingAware {
/** The Base-64 alphabet.
*/
private static final char ALPHABET[] = {
'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', '+', '/', '=' };
/** Deny construction of this class.
*/
private EncodingTools() { }
/* ====================================================================== */
/* URL ENCODING / DECODING */
/* ====================================================================== */
/**
* Return the {@link String} representation of the specified
* {@link Encodable} object using the {@link EncodingAware#DEFAULT_ENCODING
* default encoding}.
*
* throws NullPointerException if the {@link Encodable} was null.
*/
public static String toString(Encodable encodable) {
try {
return encodable.toString(DEFAULT_ENCODING);
} catch (UnsupportedEncodingException exception) {
final String message = "Default encoding \"" + DEFAULT_ENCODING +
"\" not supported by the platform";
final InternalError error = new InternalError(message);
throw (InternalError) error.initCause(exception);
}
}
/* ====================================================================== */
/* URL ENCODING / DECODING */
/* ====================================================================== */
/**
* URL-encode the specified string.
*/
public static String urlEncode(String source, String encoding)
throws UnsupportedEncodingException {
if (source == null) return null;
if (encoding == null) encoding = DEFAULT_ENCODING;
return URLEncoder.encode(source, encoding);
}
/**
* URL-encode the specified string.
*/
public static String urlEncode(String source) {
if (source == null) return null;
try {
return URLEncoder.encode(source, DEFAULT_ENCODING);
} catch (UnsupportedEncodingException exception) {
final String message = "Unsupported encoding " + DEFAULT_ENCODING;
final InternalError error = new InternalError(message);
throw (InternalError) error.initCause(exception);
}
}
/**
* URL-decode the specified string.
*/
public static String urlDecode(String source, String encoding)
throws UnsupportedEncodingException {
if (source == null) return null;
if (encoding == null) encoding = DEFAULT_ENCODING;
return URLDecoder.decode(source, encoding);
}
/**
* URL-decode the specified string.
*/
public static String urlDecode(String source) {
if (source == null) return null;
try {
return URLDecoder.decode(source, DEFAULT_ENCODING);
} catch (UnsupportedEncodingException exception) {
final String message = "Unsupported encoding " + DEFAULT_ENCODING;
final InternalError error = new InternalError(message);
throw (InternalError) error.initCause(exception);
}
}
/* ====================================================================== */
/* BASE 64 ENCODING / DECODING */
/* ====================================================================== */
/**
* Encode the specified string in base 64 using the specified
* encoding.
*/
public static final String base64Encode(String string, String encoding)
throws UnsupportedEncodingException {
/* Check the source string for null or the empty string. */
if (string == null) return (null);
if (string.length() == 0) return "";
/* Check the encoding */
if (encoding == null) encoding = DEFAULT_ENCODING;
/* Prepare the buffers that we'll use to encode in Base 64 */
final byte bsrc[] = string.getBytes(encoding);
final char bdst[] = new char[(bsrc.length + 2) / 3 * 4];
/* Iterate into the source in chunks of three bytes */
int psrc = -1;
int pdst = 0;
int temp = 0;
while ((psrc = psrc + 3) < bsrc.length) {
/* For every three bytes processed ... */
temp = ((bsrc[psrc - 2] << 16) & 0xFF0000) |
((bsrc[psrc - 1] << 8) & 0x00FF00) |
((bsrc[psrc ] ) & 0x0000FF);
/* ... we append four bytes to the buffer */
bdst[pdst ++] = ALPHABET[(temp >> 18) & 0x3f];
bdst[pdst ++] = ALPHABET[(temp >> 12) & 0x3f];
bdst[pdst ++] = ALPHABET[(temp >> 6) & 0x3f];
bdst[pdst ++] = ALPHABET[(temp ) & 0x3f];
}
/* Let's check whether we still have some bytes to encode */
switch (psrc - bsrc.length) {
case 0: /* Two bytes left to encode */
temp = ((bsrc[psrc - 2] & 0xFF) << 8) | (bsrc[psrc - 1] & 0xFF);
bdst[pdst ++] = ALPHABET[(temp >> 10) & 0x3f];
bdst[pdst ++] = ALPHABET[(temp >> 4) & 0x3f];
bdst[pdst ++] = ALPHABET[(temp << 2) & 0x3c];
bdst[pdst ++] = ALPHABET[64];
break;
case 1: /* One byte left to encode */
temp = (bsrc[psrc - 2] & 0xFF);
bdst[pdst ++] = ALPHABET[(temp >> 2) & 0x3f];
bdst[pdst ++] = ALPHABET[(temp << 4) & 0x30];
bdst[pdst ++] = ALPHABET[64];
bdst[pdst ++] = ALPHABET[64];
}
/* Convert the character array into a proper string */
return new String(bdst);
}
/**
* Encode the specified string in base 64 using the default encoding.
*/
public static final String base64Encode(String string) {
try {
return (base64Encode(string, DEFAULT_ENCODING));
} catch (UnsupportedEncodingException exception) {
final String message = "Unsupported encoding " + DEFAULT_ENCODING;
final InternalError error = new InternalError(message);
throw (InternalError) error.initCause(exception);
}
}
/**
* Decode the specified base 64 string using the specified encoding.
*/
public static final String base64Decode(String string, String encoding)
throws UnsupportedEncodingException {
/* Check the source string for null or the empty string. */
if (string == null) return (null);
if (string.length() == 0) return "";
/* Check the encoding */
if (encoding == null) encoding = DEFAULT_ENCODING;
/* Retrieve the array of characters of the source string. */
final char characters[] = string.toCharArray();
/* Check the length, which must be dividible by 4. */
if ((characters.length & 0x03) != 0)
throw new IllegalArgumentException("Invalid length for the "+
"encoded string (" + characters.length + ")");
/* The bytes array length is 3/4th of the characters array length */
byte bytes[] = new byte[characters.length - (characters.length >> 2)];
/*
* Since this might take a while check now for the last 4 characters
* token: it must contain at most two == and those need to be in the
* last two positions in the array (the only valid sequences are:
* "????", "???=" and "??==").
*/
if (((characters[characters.length - 4] == '=') ||
(characters[characters.length - 3] == '=')) ||
((characters[characters.length - 2] == '=') &&
(characters[characters.length - 1] != '='))) {
throw new IllegalArgumentException("Invalid pattern for last " +
"Base64 token in string to decode: " +
characters[characters.length - 4] +
characters[characters.length - 3] +
characters[characters.length - 2] +
characters[characters.length - 1]);
}
/* Translate the Base64-encoded String in chunks of 4 characters. */
int coff = 0;
int boff = 0;
while (coff < characters.length) {
boolean last = (coff == (characters.length - 4));
int curr = ((value(characters[coff ], last) << 0x12) |
(value(characters[coff + 1], last) << 0x0c) |
(value(characters[coff + 2], last) << 0x06) |
(value(characters[coff + 3], last) ));
bytes[boff + 2] = (byte)((curr ) & 0xff);
bytes[boff + 1] = (byte)((curr >> 0x08) & 0xff);
bytes[boff ] = (byte)((curr >> 0x10) & 0xff);
coff += 4;
boff += 3;
}
/* Get the real decoded string length, checking out the trailing '=' */
if (characters[coff - 1] == '=') boff--;
if (characters[coff - 2] == '=') boff--;
/* All done */
return (new String(bytes, 0, boff, encoding));
}
/**
* Decode the specified base 64 string using the default encoding.
*/
public static final String base64Decode(String string) {
try {
return (base64Decode(string, DEFAULT_ENCODING));
} catch (UnsupportedEncodingException exception) {
final String message = "Unsupported encoding " + DEFAULT_ENCODING;
final InternalError error = new InternalError(message);
throw (InternalError) error.initCause(exception);
}
}
/* ====================================================================== */
/** Retrieve the offset of a character in the base 64 alphabet.
*/
private static final int value(char character, boolean last) {
for (int x = 0; x < 64; x++) if (ALPHABET[x] == character) return (x);
if (last && (character == ALPHABET[65])) return(0);
final String message = "Character \"" + character + "\" invalid";
throw new IllegalArgumentException(message);
}
}
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