Decodes values of attributes in the DN encoded in hex into a UTF-8 String. : Unicode « Development « Java Tutorial

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import java.io.UnsupportedEncodingException;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import javax.naming.InvalidNameException;

/*
 *  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. 
 *  
 */



/**
 * Various string manipulation methods that are more efficient then chaining
 * string operations: all is done in the same buffer without creating a bunch of
 * string objects.
 * 
 * @author <a href="mailto:dev@labs.apache.org">Dungeon Project</a>
 */
public class Main {
  /** &lt;hex> ::= [0x30-0x39] | [0x41-0x46] | [0x61-0x66] */
  private static final byte[] HEX_VALUE =
      { 
          -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00 -> 0F
          -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10 -> 1F
          -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 20 -> 2F
           0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1, // 30 -> 3F ( 0, 1,2, 3, 4,5, 6, 7, 8, 9 )
          -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 40 -> 4F ( A, B, C, D, E, F )
          -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 50 -> 5F
          -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1  // 60 -> 6F ( a, b, c, d, e, f )
      };
  /**
   * Decodes values of attributes in the DN encoded in hex into a UTF-8 
   * String.  RFC2253 allows a DN's attribute to be encoded in hex.
   * The encoded value starts with a # then is followed by an even 
   * number of hex characters.  
   */
  public static final String decodeHexString( String str ) throws InvalidNameException
  {
      if ( str == null || str.length() == 0 )
      {
          throw new InvalidNameException( "Expected string to start with a '#' character.  " +
              "Invalid hex encoded string for empty or null string."  );
      }
      
      char[] chars = str.toCharArray();
      if ( chars[0] != '#' )
      {
          throw new InvalidNameException( "Expected string to start with a '#' character.  " +
                  "Invalid hex encoded string: " + str  );
      }
      
      // the bytes representing the encoded string of hex
      // this should be ( length - 1 )/2 in size
      byte[] decoded = new byte[ ( chars.length - 1 ) >> 1 ];

      for ( int ii = 1, jj = 0 ; ii < chars.length; ii+=2, jj++ )
      {
          int ch = ( HEX_VALUE[chars[ii]] << 4 ) + 
              HEX_VALUE[chars[ii+1]];
          decoded[jj] = ( byte ) ch;
      }
      
      return utf8ToString( decoded );
  }
  /**
   * Return an UTF-8 encoded String
   * 
   * @param bytes
   *            The byte array to be transformed to a String
   * @return A String.
   */
  public static final String utf8ToString( byte[] bytes )
  {
      if ( bytes == null )
      {
          return "";
      }

      try
      {
          return new String( bytes, "UTF-8" );
      }
      catch ( UnsupportedEncodingException uee )
      {
          return "";
      }
  }
}