16 binary and Byte conversions

This article turns from: http://franksinger.iteye.com/blog/614540

In Java, byte is used in binary notation to occupy 8 bits, and we know that each character of the 16 binary needs to be represented by 4-bit bits (23 + 22 + 21 + 20 = 15), so we can convert each byte to two corresponding 16 characters. That is, the high 4 bits of byte and the lower 4 bits are converted to the corresponding 16-character H and L and combined to get the result of the byte conversion to the 16 string, new String (H) + new String (L). That is, byte in hexadecimal notation only occupies 2 digits.

In the same way, the opposite conversion converts two 16 characters into a byte, as in principle.

Based on the above principles, we can convert the byte[] array to a 16 binary string, and of course we can convert the 16 string into a byte[] array.

/**

   * convert byte[] to hex string. Here we can convert byte to int and then use integer.tohexstring ( int) to convert to a 16 binary string.     *  @param  src byte[] data     *  @return  hex  String     */       public static string bytestohexstring ( BYTE[]&NBSP;SRC) {       StringBuilder stringBuilder = new  StringBuilder ("");        if  (src == null | |  src.length <= 0)  {           return  null;       &nbsp}        for  int i = 0;  i < src.length; i++)  {            int v = src[i] & 0xFF;    &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBsp;  string hv = integer.tohexstring (v);            if  (Hv.length ()  < 2)  {                stringbuilder.append (0);            }             stringbuilder.append (HV);       &nbsp        return stringbuilder.tostring ();   }   /**    * Convert hex string to byte[]     *  @param  hexString the hex string    *  @return   byte[]    */   public static byte[] hexstringtobytes (string  hexstring)  {       if  (hexstring == null | |  hexstring.equals ("")) {           return null;       &NBSP;&NBSP}        hexstring = hexstring.touppercase ();        int length = hexstring.length ()  / 2;        char[] hexchars = hexstring.tochararray ();        byte[] d = new byte[length];        for  (int i = 0; i < length; i++ )  {           int pos = i * 2;            d[i] =  (Byte)   (Chartobyte hexchars[ POS])  << 4 | chartobyte (hexchars[pos + 1]);        }        return d;   }   /**    * Convert char to byte    * @ param c char    *  @return  byte    */