架构师训练营第十一周作业

/**
	 * 将byte数组表示为十六进制格式的字符串
	 * @param bytes
	 * @return
	 */
	public String bytes2Hex(byte[] bytes) {
		StringBuffer stringBuffer = new StringBuffer();
		String hex = null;
		for (int i = 0; i < bytes.length; ++i) {
			hex = Integer.toHexString(bytes[i] & 0xFF);
			stringBuffer.append(hex.length() == 1 ? "0" + hex : hex);
		}
		return stringBuffer.toString();
	}
	
	/**
	 * SHA256加密
	 * @param 明文字符串
	 * @return 加密后的报文
	 */
	public String getSHA256Str(String str) {
		MessageDigest messageDigest;
		String encoded = "";
		try {
			messageDigest = MessageDigest.getInstance("SHA-256");
			messageDigest.update(str.getBytes("UTF-8"));
			encoded = bytes2Hex(messageDigest.digest());
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		return encoded;
	}
	
	/**
	 * 校验用户密码
	 * @param userId 用户ID
	 * @param password 明文密码
	 * @param savedPassword 数据库保存的密文密码
	 * @return
	 */
	public boolean checkPW(String userId, String password, String savedPassword) {
		String encodedPassword = getSHA256Str(userId + "-" + password);
		return encodedPassword.equals(savedPassword);
	}