java MessageDigest类使用MD5加密算法加密n次

源代码：

package com.oracle.core;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Scanner;

public class Knife
{
	static Scanner scanner=new Scanner(System.in);

	public static void main(String[] args) throws NoSuchAlgorithmException, CloneNotSupportedException
	{
		Knife knife = new Knife();
		System.out.println("请输入您要加密的数");
		String str=scanner.next();
		MessageDigest instance = MessageDigest.getInstance("MD5");
		instance.update(str.getBytes());
		MessageDigest tc1 = (MessageDigest) instance.clone();
		byte[] digest = tc1.digest();
		String md5 = knife.convertbyte2String(digest);
		System.out.println("请输入您要加密的次数:");
		int n=scanner.nextInt();
		String md51 = md5("123456",n );
		System.out.println(str+"加密"+n+"次后的结果为"+"\n"+md51);
	}

	public static String md5(String keyword, int count) throws NoSuchAlgorithmException, CloneNotSupportedException
	{

		for (int i = 0; i < count; i++)
		{
			MessageDigest instance = MessageDigest.getInstance("MD5");
			instance.update(keyword.getBytes()); // 加密
			MessageDigest tc1 = (MessageDigest) instance.clone();
			byte[] digest = tc1.digest(); // 字母+数字
			keyword = Knife.convertbyte2String(digest);
		}
		return keyword;
	}

	private static String convertbyte2String(byte[] byteResult)
	{
		char[] hexDigits =
		{ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

		// 4位代表一个16进制，所以长度需要变为原来2倍
		char[] result = new char[byteResult.length * 2];

		int index = 0;
		for (byte b : byteResult)
		{
			// 先转换高4位
			result[index++] = hexDigits[(b >>> 4) & 0xf];
			result[index++] = hexDigits[b & 0xf];
		}
		return new String(result);
	}
}

运行结果：