MD5算法-参考网上的资料改写

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5 {
    
    private MessageDigest __digest = null;

    public String ToMD5(String s)
    {
        try{
            __digest=MessageDigest.getInstance("MD5");
        }
        catch (NoSuchAlgorithmException e)
      {
         System.err.println("Failed to load the MD5 MessageDigest. ");
         e.printStackTrace();
         return null;
      }
      
      __digest.update(s.getBytes());
      return toHex(__digest.digest());
    }

    private String toHex(byte[] bytes){
        String HEX="0123456789ABCDEF";
        String data="";
        char a,b;

        for (int i = 0; i < bytes.length; i++)
        {
            a=HEX.charAt((bytes[i] & 0xf0) >> 4);
            b=HEX.charAt(bytes[i] & 0x0f);
            data=data + a + b;
        }
        return data;
    }
}