Decodes Hex data into octects : Hex Oct « Data Type « Java Tutorial






/*   Copyright 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.
 */

//xmlbeans

import java.io.UnsupportedEncodingException;
/**
 * format validation
 *
 * This class encodes/decodes hexadecimal data
 * @author Jeffrey Rodriguez
 * @version $Id: HexBin.java 125124 2005-01-14 00:23:54Z kkrouse $
 */
public class Main {
  static private final int  BASELENGTH   = 255;
  static private final int  LOOKUPLENGTH = 16;
  static private byte [] hexNumberTable    = new byte[BASELENGTH];
  static private byte [] lookUpHexAlphabet = new byte[LOOKUPLENGTH];


  static {
      for (int i = 0; i<BASELENGTH; i++ ) {
          hexNumberTable[i] = -1;
      }
      for ( int i = '9'; i >= '0'; i--) {
          hexNumberTable[i] = (byte) (i-'0');
      }
      for ( int i = 'F'; i>= 'A'; i--) {
          hexNumberTable[i] = (byte) ( i-'A' + 10 );
      }
      for ( int i = 'f'; i>= 'a'; i--) {
         hexNumberTable[i] = (byte) ( i-'a' + 10 );
      }

      for(int i = 0; i<10; i++ )
          lookUpHexAlphabet[i] = (byte) ('0'+i );
      for(int i = 10; i<=15; i++ )
          lookUpHexAlphabet[i] = (byte) ('A'+i -10);
  }



  /**
   * Decodes Hex data into octects
   *
   * @param binaryData String containing Hex data
   * @return string containing decoded data.
   */
  public static String decode(String binaryData) {
      if (binaryData == null)
          return null;

      byte[] decoded = null;
      try {
        decoded = decode(binaryData.getBytes("utf-8"));
      }
      catch(UnsupportedEncodingException e) {
      }
      return decoded == null ? null : new String(decoded);
  }
  static public byte[] decode(byte[] binaryData) {
      if (binaryData == null)
          return null;
      int lengthData   = binaryData.length;
      if (lengthData % 2 != 0)
          return null;

      int lengthDecode = lengthData / 2;
      byte[] decodedData = new byte[lengthDecode];
      for( int i = 0; i<lengthDecode; i++ ){
          if (!isHex(binaryData[i*2]) || !isHex(binaryData[i*2+1])) {
              return null;
          }
          decodedData[i] = (byte)((hexNumberTable[binaryData[i*2]] << 4) | hexNumberTable[binaryData[i*2+1]]);
      }
      return decodedData;
  }

  /**
   * byte to be tested if it is Base64 alphabet
   *
   * @param octect
   * @return
   */
  static boolean isHex(byte octect) {
      return (hexNumberTable[octect] != -1);
  }
}








2.9.Hex Oct
2.9.1.Hexadecimal integer literal
2.9.2.A hexadecimal literal of type long
2.9.3.Defining integer literals as octal values
2.9.4.Decode string to integer
2.9.5.Convert octal number to decimal number example
2.9.6.Convert decimal integer to octal number example
2.9.7.Convert decimal integer to hexadecimal number example
2.9.8.Parsing and Formatting a Number into Binary
2.9.9.Convert byte array to Hex String
2.9.10.Convert the bytes to a hex string representation of the bytes
2.9.11.Converting hexadecimal strings
2.9.12.Dumps data in hexadecimal format
2.9.13.Given a hexstring this will return the byte array corresponding to string
2.9.14.Hex encoder/decoder implementation borrowed from BouncyCastle
2.9.15.Returns the hexadecimal value of the supplied byte array
2.9.16.A custom number formatter that formats numbers as hexadecimal strings.
2.9.17.Decodes Hex data into octects
2.9.18.Decodes Base64 data into octects
2.9.19.Helper function that returns a char from an hex
2.9.20.Encodes hex octects into Base64
2.9.21.Hex encoder and decoder.
2.9.22.Helper function that dump an array of bytes in hex pair form, without '0x' and space chars
2.9.23.dump an array of bytes in hex form
2.9.24.Decode byte array