支付宝某个鉴权文档中，有段 Java 代码样例，本人 Python 写的比较多, Java 不太熟，想转成 Python 代码

接主题，java 代码如下:

public String getCheckSum(String requestBody, String appSecret, String time) {

String md5Digest = MessageDigestUtils.md5Digest(requestBody); 
String checksum = MessageDigestUtils.sha1Digest(appSecret, md5Digest, time);

return checksum;

}

public class MessageDigestUtils {

private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};

private MessageDigestUtils() {
}

public static String md5Digest(String input) {
    StringBuilder hexValue = new StringBuilder();

    try {

        MessageDigest md5 = MessageDigest.getInstance("MD5");
        byte[] md5Bytes = md5.digest(input.getBytes(StandardCharsets.UTF_8));

        for (byte md5Byte : md5Bytes) {
            int val = ((int) md5Byte) & 0xff;
            if (val < 16) {
                hexValue.append("0");
            }
            hexValue.append(Integer.toHexString(val));
        }
    } catch (Exception e) {
        
    }

    return hexValue.toString();
}

public static String sha1Digest(String appSecret, String nonce, String time) {
    String content = appSecret + nonce + time;
    try {
        MessageDigest messageDigest = MessageDigest.getInstance("sha1");
        messageDigest.update(content.getBytes());
        return getFormattedText(messageDigest.digest());
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
}

private static String getFormattedText(byte[] bytes) {
    int len = bytes.length;
    StringBuilder buf = new StringBuilder(len * 2);
    for (int j = 0; j < len; j++) {
        buf.append(HEX_DIGITS[(bytes[j] >> 4) & 0x0f]);
        buf.append(HEX_DIGITS[bytes[j] & 0x0f]);
    }
    return buf.toString();
}

}