//消息摘要：将任意长度的字符数组处理成定长的字符数组，用于确保原字符串不被修改，

//也可以用做密码确认，如果密码一致，则MD5产生后的值必然一致，否则不相同

public class DataUtil {

    public static void main(String[] args) throws Exception {

        char[] ch={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F',};

        String src= "唐";

        StringBuffer sb=new StringBuffer();

        byte[] b1=src.getBytes();

        System.out.println("-----------"+b1.length);

        for(byte b:b1){

            System.out.print(b+"  ");

        }

        System.out.println();

        MessageDigest md= MessageDigest.getInstance("MD5");

        byte[] b2=md.digest(b1);

        System.out.println("-------"+b2.length);

        for(byte b:b2){

            System.out.print(b+" ");

            //高四位

            sb.append(ch[b>>4 & 0x0F]);

            //低四位

            sb.append(ch[b & 0x0F]);

        }

        System.out.println();

        System.out.println(sb.length()+":"+sb.toString());

    }

}