package com.caimei.utils;

import java.security.MessageDigest;
import java.util.UUID;

/**
 * @author : Charles
 * @description : Description
 * @date : 2020/1/3
 */
public class MD5Util {
    /**
	 * md5加密
	 * @param s：待加密字符串
	 * @return 加密后16进制字符串
	 */
	public static String md5(String s) {
	    try {
	    	//实例化MessageDigest的MD5算法对象
	        MessageDigest md = MessageDigest.getInstance("MD5");
	        //通过digest方法返回哈希计算后的字节数组
	        byte[] bytes = md.digest(s.getBytes("utf-8"));
	        //将字节数组转换为16进制字符串并返回
	        return toHex(bytes);
	    }
	    catch (Exception e) {
	        throw new RuntimeException(e);
	    }
	}
	/**
	 * 获取随即盐
	 * @return
	 */
	public static String salt(){
		//利用UUID生成随机盐
		UUID uuid = UUID.randomUUID();
		//返回a2c64597-232f-4782-ab2d-9dfeb9d76932
		String[] arr = uuid.toString().split("-");
		return arr[0];
	}
	/**
	 * 字节数组转换为16进制字符串
	 * @param bytes数组
	 * @return 16进制字符串
	 */
	private static String toHex(byte[] bytes) {
	    final char[] HEX_DIGITS = "0123456789ABCDEF".toCharArray();
	    StringBuilder ret = new StringBuilder(bytes.length * 2);
	    for (int i=0; i<bytes.length; i++) {
	        ret.append(HEX_DIGITS[(bytes[i] >> 4) & 0x0f]);
	        ret.append(HEX_DIGITS[bytes[i] & 0x0f]);
	    }
	    return ret.toString();
	}

}