On hex Coding algorithm

First, what is hex

The hexadecimal representation of each byte represents the content, displayed in a string.

Second, the role

Converts an invisible, complex array of bytes data into a string data that can be displayed

Similar to BASE64 encoding algorithm

Difference: Base64 converts three bytes to four characters, Hex converts three bytes to six bytes

Third, the application scenario

Use when you include invisible data (binary data) in text such as Xml,json

Iv. Use of

1. Converting a byte array to a string

1 /**2 * Converts a byte array to a string3 * One byte will form two characters, the final length is twice times the original data4 * @param data5 * @return6      */7      Public StaticString Tohex (byte[] data) {8String ret =NULL;9 Ten         //TODO converts a byte array to a string One         if(Data! =NULL&& data.length>0) { AStringBuilder SB =NewStringBuilder (); -              for(byteb:data) { -                 //get four-bit, four-bit low content, and convert two values to characters the                 intH = (b>>4) &0x0f; -                 intL = b&0x0f; -                 Charch, cl; -                 if(H >9 ){ +CH = (Char) ('A'+ (H-Ten)); -}Else{//0--9 +CH = (Char) ('0'+h); A                 } at  -                 if(l>9){ -CL = (Char) ('A'+ (L-Ten)); -}Else{//0--9 -CL = (Char) ('0'+l); -                 } in  -  to sb.append (CH). Append (CL); +                 } -RET =sb.tostring (); the             } *  $         returnret;Panax Notoginseng}

2. Converting a string to a byte array

1   Public Static byte[] Fromhex (String str) {2         byte[] ret =NULL;3 4         //TODO restores hex-encoded string to original byte array5         if(str! =NULL) {6             intLen =str.length ();7             if(Len >0&& len%2==0) {8                 Char[] CHS =Str.tochararray ();9RET =New byte[Len/2];Ten                  for(inti =0, j =0; i < Len; i + =2, J + +) { One                     CharCH =Chs[i]; A                     CharCL = Chs[i +1]; -  -                     intIH =0, IL =0, V =0; the                     if(Ch >='A'&& CH <='F') { -IH =Ten+ (CH-'A'); -}Else if(Ch >='a'&& CH <='F') { -IH =Ten+ (CH-'a'); +}Else if(Ch >='0'&& CH <='9') { -IH = CH-'0'; +                     } A  at                     if(CL >='A'&& CL <='F') { -Il =Ten+ (CL-'A'); -}Else if(CL >='a'&& CL <='F') { -Il =Ten+ (CL-'a'); -}Else if(CL >='0'&& CL <='9') { -Il = CL-'0'; in                     } -  tov = (IH &0x0f) <<4) | (Il &0x0f); +                     //Assign Value -RET[J] = (byte) v; the                 } *             } $         }Panax Notoginseng         returnret; -}

On hex Coding algorithm