javascript/296131.html">java;">import java.security.MessageDigest;public class MD5 {	//公鹽	private static final String PUBLIC_SALT = "demo" ;	//十六進制下數字到字符的映射數組 	private final static String[] hexDigits = {"0", "1", "2", "3", "4", 	  "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};	/**  * 用戶密碼加密，鹽值為 ：私鹽+公鹽  * @param password 密碼  * @param salt 私鹽  * @return MD5加密字符串  */	public static String encryptPassword(String password,String salt){		return encodeByMD5(PUBLIC_SALT+password+salt);	}	/**  * md5加密算法  * @param originString  * @return   */	private static String encodeByMD5(String originString){		if (originString != null){			try{				//創建具有指定算法名稱的信息摘要 				MessageDigest md = MessageDigest.getInstance("MD5");				//使用指定的字節數組對摘要進行最后更新，然后完成摘要計算 				byte[] results = md.digest(originString.getBytes());				//將得到的字節數組變成字符串返回 				String resultString = byteArrayToHexString(results);				return resultString.toUpperCase();			}			catch(Exception ex){				ex.printStackTrace();			}		}		return null;	}	/**   * 轉換字節數組為十六進制字符串   * @param  字節數組   * @return 十六進制字符串   */	private static String byteArrayToHexString(byte[] b){		StringBuffer resultSb = new StringBuffer();		for (int i = 0; i < b.length; i++){			resultSb.append(byteToHexString(b[i]));		}		return resultSb.toString();	}	/** 將一個字節轉化成十六進制形式的字符串  */	private static String byteToHexString(byte b){		int n = b;		if (n < 0) 		   n = 256 + n;		int d1 = n / 16;		int d2 = n % 16;		return hexDigits[d1] + hexDigits[d2];	}}