MD5算法原理

//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());

    }
}