MD5基本算法

手動實現MD5 跟官方的MD5加密結果一致

package com.atguigu.survey.md5;

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

public class Md5Test {
	
	public static void main(String[] args) throws NoSuchAlgorithmException {
		
		String source = "123123";
		byte[] bytes = source.getBytes();
		MessageDigest messageDigest = MessageDigest.getInstance("md5");  //首先用java的md5進行一次加密先 
		byte[] digest = messageDigest.digest(bytes);
		char[] characters = new char[] {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};		//自己進行加密
		StringBuilder builder = new StringBuilder();
		for (int i = 0; i < digest.length; i++) {	
			byte b = digest[i];
			int lowValue = b & 15;
			int highValue = (b >> 4) & 15;
			char lowChar = characters[lowValue];
			char highChar = characters[highValue];
			builder.append(highChar).append(lowChar);
		}
		System.out.println(builder.toString());
		
	}
		
}