org.apache.wicket.util.encoding.UrlDecoder Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package org.apache.wicket.util.encoding;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import org.apache.wicket.util.string.Strings;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Adapted from java.net.URLDecoder, but defines instances for query string decoding versus URL path
* component decoding.
*
* The difference is important because a space is encoded as a + in a query string, but this is a
* valid value in a path component (and is therefore not decode back to a space).
*
* @author Doug Donohoe
* @see java.net.URLDecoder
* @see RFC-2396
*/
public class UrlDecoder
{
private static final Logger LOG = LoggerFactory.getLogger(UrlDecoder.class);
private final boolean decodePlus;
/**
* Encoder used to decode name or value components of a query string.
*
*
* For example: http://org.acme/notthis/northis/oreventhis?buthis=isokay&asis=thispart
*/
public static final UrlDecoder QUERY_INSTANCE = new UrlDecoder(true);
/**
* Encoder used to decode components of a path.
*
*
* For example: http://org.acme/foo/thispart/orthispart?butnot=thispart
*/
public static final UrlDecoder PATH_INSTANCE = new UrlDecoder(false);
/**
* Create decoder
*
* @param decodePlus
* - whether to decode + to space
*/
private UrlDecoder(final boolean decodePlus)
{
this.decodePlus = decodePlus;
}
/**
* @param s
* string to decode
* @param enc
* encoding to decode with
* @return decoded string
* @see java.net.URLDecoder#decode(String, String)
*/
public String decode(final String s, final Charset enc)
{
return decode(s, enc.name());
}
/**
* @param s
* string to decode
* @param enc
* encoding to decode with
* @return decoded string
* @see java.net.URLDecoder#decode(String, String)
*/
public String decode(final String s, final String enc)
{
if (Strings.isEmpty(s))
{
return s;
}
int numChars = s.length();
StringBuilder sb = new StringBuilder(numChars > 500 ? numChars / 2 : numChars);
int i = 0;
if (enc.length() == 0)
{
throw new RuntimeException(new UnsupportedEncodingException(
"URLDecoder: empty string enc parameter"));
}
char c;
byte[] bytes = null;
while (i < numChars)
{
c = s.charAt(i);
switch (c)
{
case '+' :
sb.append(decodePlus ? ' ' : '+');
i++;
break;
case '%' :
/*
* Starting with this instance of %, process all consecutive substrings of the
* form %xy. Each substring %xy will yield a byte. Convert all consecutive bytes
* obtained this way to whatever character(s) they represent in the provided
* encoding.
*/
try
{
// (numChars-i)/3 is an upper bound for the number
// of remaining bytes
if (bytes == null)
{
bytes = new byte[(numChars - i) / 3];
}
int pos = 0;
while (((i + 2) < numChars) && (c == '%'))
{
bytes[pos++] = (byte)Integer.parseInt(s.substring(i + 1, i + 3), 16);
i += 3;
if (i < numChars)
{
c = s.charAt(i);
}
}
// A trailing, incomplete byte encoding such as
// "%x" will cause an exception to be thrown
if ((i < numChars) && (c == '%'))
{
LOG.info("Incomplete trailing escape (%) pattern in '%s'. The escape character (%) will be ignored.",
s);
i++;
break;
}
try
{
sb.append(new String(bytes, 0, pos, enc));
}
catch (UnsupportedEncodingException e)
{
throw new RuntimeException(e);
}
}
catch (NumberFormatException e)
{
LOG.info("Illegal hex characters in escape (%) pattern in '{}'. " +
"The escape character (%) will be ignored. NumberFormatException: {} ",
s, e.getMessage());
i++;
}
break;
default :
sb.append(c);
i++;
break;
}
}
// no trying to filter out bad escapes beforehand, just kill all null bytes here at the end,
// that way none will come through
return sb.toString().replace("\0", "NULL");
}
}