Implements the 'www-form-urlencoded' encoding scheme, also misleadingly known as URL encoding.
/*
* Copyright 2001-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* 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.
*/
import java.io.ByteArrayOutputStream;
import java.io.UnsupportedEncodingException;
import java.util.BitSet;
/**
* <p>Implements the 'www-form-urlencoded' encoding scheme,
* also misleadingly known as URL encoding.</p>
*
* <p>For more detailed information please refer to
* <a href="http://www.w3.org/TR/html4/interact/forms.html#h-17.13.4.1">
* Chapter 17.13.4 'Form content types'</a> of the
* <a href="http://www.w3.org/TR/html4/">HTML 4.01 Specification<a></p>
*
* <p>
* This codec is meant to be a replacement for standard Java classes
* {@link java.net.URLEncoder} and {@link java.net.URLDecoder}
* on older Java platforms, as these classes in Java versions below
* 1.4 rely on the platform's default charset encoding.
* </p>
*
* @author Apache Software Foundation
* @since 1.2
* @version $Id: URLCodec.java,v 1.19 2004/03/29 07:59:00 ggregory Exp $
*/
public class URLCodec {
/**
* The default charset used for string decoding and encoding.
*/
protected String charset = "UTF8";
protected static byte ESCAPE_CHAR = '%';
/**
* BitSet of www-form-url safe characters.
*/
protected static final BitSet WWW_FORM_URL = new BitSet(256);
// Static initializer for www_form_url
static {
// alpha characters
for (int i = 'a'; i <= 'z'; i++) {
WWW_FORM_URL.set(i);
}
for (int i = 'A'; i <= 'Z'; i++) {
WWW_FORM_URL.set(i);
}
// numeric characters
for (int i = '0'; i <= '9'; i++) {
WWW_FORM_URL.set(i);
}
// special chars
WWW_FORM_URL.set('-');
WWW_FORM_URL.set('_');
WWW_FORM_URL.set('.');
WWW_FORM_URL.set('*');
// blank to be replaced with +
WWW_FORM_URL.set(' ');
}
/**
* Default constructor.
*/
public URLCodec() {
super();
}
/**
* Constructor which allows for the selection of a default charset
*
* @param charset the default string charset to use.
*/
public URLCodec(String charset) {
super();
this.charset = charset;
}
/**
* Encodes an array of bytes into an array of URL safe 7-bit
* characters. Unsafe characters are escaped.
*
* @param urlsafe bitset of characters deemed URL safe
* @param bytes array of bytes to convert to URL safe characters
* @return array of bytes containing URL safe characters
*/
public static final byte[] encodeUrl(BitSet urlsafe, byte[] bytes)
{
if (bytes == null) {
return null;
}
if (urlsafe == null) {
urlsafe = WWW_FORM_URL;
}
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
for (int i = 0; i < bytes.length; i++) {
int b = bytes[i];
if (b < 0) {
b = 256 + b;
}
if (urlsafe.get(b)) {
if (b == ' ') {
b = '+';
}
buffer.write(b);
} else {
buffer.write('%');
char hex1 = Character.toUpperCase(
Character.forDigit((b >> 4) & 0xF, 16));
char hex2 = Character.toUpperCase(
Character.forDigit(b & 0xF, 16));
buffer.write(hex1);
buffer.write(hex2);
}
}
return buffer.toByteArray();
}
/**
* Decodes an array of URL safe 7-bit characters into an array of
* original bytes. Escaped characters are converted back to their
* original representation.
*
* @param bytes array of URL safe characters
* @return array of original bytes
* @throws DecoderException Thrown if URL decoding is unsuccessful
*/
public static final byte[] decodeUrl(byte[] bytes)
throws Exception
{
if (bytes == null) {
return null;
}
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
for (int i = 0; i < bytes.length; i++) {
int b = bytes[i];
if (b == '+') {
buffer.write(' ');
} else if (b == '%') {
try {
int u = Character.digit((char)bytes[++i], 16);
int l = Character.digit((char)bytes[++i], 16);
if (u == -1 || l == -1) {
throw new RuntimeException("Invalid URL encoding");
}
buffer.write((char)((u << 4) + l));
} catch(ArrayIndexOutOfBoundsException e) {
throw new RuntimeException("Invalid URL encoding");
}
} else {
buffer.write(b);
}
}
return buffer.toByteArray();
}
/**
* Encodes an array of bytes into an array of URL safe 7-bit
* characters. Unsafe characters are escaped.
*
* @param bytes array of bytes to convert to URL safe characters
* @return array of bytes containing URL safe characters
*/
public byte[] encode(byte[] bytes) {
return encodeUrl(WWW_FORM_URL, bytes);
}
/**
* Decodes an array of URL safe 7-bit characters into an array of
* original bytes. Escaped characters are converted back to their
* original representation.
*
* @param bytes array of URL safe characters
* @return array of original bytes
* @throws DecoderException Thrown if URL decoding is unsuccessful
*/
public byte[] decode(byte[] bytes) throws Exception {
return decodeUrl(bytes);
}
/**
* Encodes a string into its URL safe form using the specified
* string charset. Unsafe characters are escaped.
*
* @param pString string to convert to a URL safe form
* @param charset the charset for pString
* @return URL safe string
* @throws UnsupportedEncodingException Thrown if charset is not
* supported
*/
public String encode(String pString, String charset)
throws UnsupportedEncodingException
{
if (pString == null) {
return null;
}
return new String(encode(pString.getBytes(charset)), "US-ASCII");
}
/**
* Encodes a string into its URL safe form using the default string
* charset. Unsafe characters are escaped.
*
* @param pString string to convert to a URL safe form
* @return URL safe string
* @throws EncoderException Thrown if URL encoding is unsuccessful
*
* @see #getDefaultCharset()
*/
public String encode(String pString) throws Exception {
if (pString == null) {
return null;
}
try {
return encode(pString, getDefaultCharset());
} catch(UnsupportedEncodingException e) {
throw new RuntimeException(e.getMessage());
}
}
/**
* Decodes a URL safe string into its original form using the
* specified encoding. Escaped characters are converted back
* to their original representation.
*
* @param pString URL safe string to convert into its original form
* @param charset the original string charset
* @return original string
* @throws DecoderException Thrown if URL decoding is unsuccessful
* @throws UnsupportedEncodingException Thrown if charset is not
* supported
*/
public String decode(String pString, String charset)
throws Exception, UnsupportedEncodingException
{
if (pString == null) {
return null;
}
return new String(decode(pString.getBytes("US-ASCII")), charset);
}
/**
* Decodes a URL safe string into its original form using the default
* string charset. Escaped characters are converted back to their
* original representation.
*
* @param pString URL safe string to convert into its original form
* @return original string
* @throws DecoderException Thrown if URL decoding is unsuccessful
*
* @see #getDefaultCharset()
*/
public String decode(String pString) throws Exception {
if (pString == null) {
return null;
}
try {
return decode(pString, getDefaultCharset());
} catch(UnsupportedEncodingException e) {
throw new RuntimeException(e.getMessage());
}
}
/**
* Encodes an object into its URL safe form. Unsafe characters are
* escaped.
*
* @param pObject string to convert to a URL safe form
* @return URL safe object
* @throws EncoderException Thrown if URL encoding is not
* applicable to objects of this type or
* if encoding is unsuccessful
*/
public Object encode(Object pObject) throws Exception {
if (pObject == null) {
return null;
} else if (pObject instanceof byte[]) {
return encode((byte[])pObject);
} else if (pObject instanceof String) {
return encode((String)pObject);
} else {
throw new RuntimeException("Objects of type " +
pObject.getClass().getName() + " cannot be URL encoded");
}
}
/**
* Decodes a URL safe object into its original form. Escaped
* characters are converted back to their original representation.
*
* @param pObject URL safe object to convert into its original form
* @return original object
* @throws DecoderException Thrown if URL decoding is not
* applicable to objects of this type
* if decoding is unsuccessful
*/
public Object decode(Object pObject) throws Exception {
if (pObject == null) {
return null;
} else if (pObject instanceof byte[]) {
return decode((byte[])pObject);
} else if (pObject instanceof String) {
return decode((String)pObject);
} else {
throw new RuntimeException("Objects of type " +
pObject.getClass().getName() + " cannot be URL decoded");
}
}
/**
* The default charset used for string decoding and encoding.
*
* @return the default string charset.
*/
public String getDefaultCharset() {
return this.charset;
}
}
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