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      1 /*
      2 * Conditions Of Use
      3 *
      4 * This software was developed by employees of the National Institute of
      5 * Standards and Technology (NIST), an agency of the Federal Government.
      6 * Pursuant to title 15 Untied States Code Section 105, works of NIST
      7 * employees are not subject to copyright protection in the United States
      8 * and are considered to be in the public domain.  As a result, a formal
      9 * license is not needed to use the software.
     10 *
     11 * This software is provided by NIST as a service and is expressly
     12 * provided "AS IS."  NIST MAKES NO WARRANTY OF ANY KIND, EXPRESS, IMPLIED
     13 * OR STATUTORY, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTY OF
     14 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT
     15 * AND DATA ACCURACY.  NIST does not warrant or make any representations
     16 * regarding the use of the software or the results thereof, including but
     17 * not limited to the correctness, accuracy, reliability or usefulness of
     18 * the software.
     19 *
     20 * Permission to use this software is contingent upon your acceptance
     21 * of the terms of this agreement
     22 *
     23 * .
     24 *
     25 */
     26 package gov.nist.javax.sip.address;
     27 
     28 import java.io.UnsupportedEncodingException;
     29 
     30 /**
     31  * Copied from Apache Excalibur project.
     32  * Source code available at http://www.google.com/codesearch?hl=en&q=+excalibur+decodePath+show:sK_gDY0W5Rw:OTjCHAiSuF0:th3BdHtpX20&sa=N&cd=1&ct=rc&cs_p=http://apache.edgescape.com/excalibur/excalibur-sourceresolve/source/excalibur-sourceresolve-1.1-src.zip&cs_f=excalibur-sourceresolve-1.1/src/java/org/apache/excalibur/source/SourceUtil.java
     33  * @author <A HREF="mailto:jean.deruelle (at) gmail.com">Jean Deruelle</A>
     34  *
     35  */
     36 public class RFC2396UrlDecoder {
     37 
     38     /**
     39      * Decode a path.
     40      *
     41      * <p>Interprets %XX (where XX is hexadecimal number) as UTF-8 encoded bytes.
     42      * <p>The validity of the input path is not checked (i.e. characters that
     43      * were not encoded will not be reported as errors).
     44      * <p>This method differs from URLDecoder.decode in that it always uses UTF-8
     45      * (while URLDecoder uses the platform default encoding, often ISO-8859-1),
     46      * and doesn't translate + characters to spaces.
     47      *
     48      * @param uri the path to decode
     49      * @return the decoded path
     50      */
     51     public static String decode(String uri) {
     52         StringBuffer translatedUri = new StringBuffer(uri.length());
     53         byte[] encodedchars = new byte[uri.length() / 3];
     54         int i = 0;
     55         int length = uri.length();
     56         int encodedcharsLength = 0;
     57         while (i < length) {
     58             if (uri.charAt(i) == '%') {
     59                 //we must process all consecutive %-encoded characters in one go, because they represent
     60                 //an UTF-8 encoded string, and in UTF-8 one character can be encoded as multiple bytes
     61                 while (i < length && uri.charAt(i) == '%') {
     62                     if (i + 2 < length) {
     63                         try {
     64                             byte x = (byte)Integer.parseInt(uri.substring(i + 1, i + 3), 16);
     65                             encodedchars[encodedcharsLength] = x;
     66                         } catch (NumberFormatException e) {
     67                             throw new IllegalArgumentException("Illegal hex characters in pattern %" + uri.substring(i + 1, i + 3));
     68                         }
     69                         encodedcharsLength++;
     70                         i += 3;
     71                     } else {
     72                         throw new IllegalArgumentException("% character should be followed by 2 hexadecimal characters.");
     73                     }
     74                 }
     75                 try {
     76                     String translatedPart = new String(encodedchars, 0, encodedcharsLength, "UTF-8");
     77                     translatedUri.append(translatedPart);
     78                 } catch (UnsupportedEncodingException e) {
     79                     //the situation that UTF-8 is not supported is quite theoretical, so throw a runtime exception
     80                     throw new RuntimeException("Problem in decodePath: UTF-8 encoding not supported.");
     81                 }
     82                 encodedcharsLength = 0;
     83             } else {
     84                 //a normal character
     85                 translatedUri.append(uri.charAt(i));
     86                 i++;
     87             }
     88         }
     89         return translatedUri.toString();
     90     }
     91 }