public final class SHA1 {

        private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5',

                '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};

        /**

         * Takes the raw bytes from the digest and formats them correct.

         *

         * @param bytes the raw bytes from the digest.

         * @return the formatted bytes.

         */

        private static String getFormattedText(byte[] bytes) {

            int len = bytes.length;

            StringBuilder buf = new StringBuilder(len * 2);

            // 把密文转换成十六进制的字符串形式

            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();

        }

        /**

         * 编码

         * */

        public static String encode(String str) {

            if (str == null) {

                return null;

            }

            try {

                MessageDigest messageDigest = MessageDigest.getInstance("SHA1");

                messageDigest.update(str.getBytes());

                return getFormattedText(messageDigest.digest());

            } catch (Exception e) {

                throw new RuntimeException(e);

            }

        }

}

  public  string SHA1(string content, Encoding encode)

        {

            try

            {

                SHA1 sha1 = new SHA1CryptoServiceProvider();

                byte[] bytes_in = encode.GetBytes(content);

                byte[] bytes_out = sha1.ComputeHash(bytes_in);

                sha1.Dispose();

                StringBuilder ret = new StringBuilder();

                foreach (byte b in bytes_out)

                {

                    //{0:X2} 大写

                    ret.AppendFormat("{0:x2}", b);

                }

                var hex = ret.ToString();

                return hex;

            }

            catch (Exception ex)

            {

                throw new Exception("SHA1加密出错：" + ex.Message);

            }

        }