/// <summary>
/// 对字符串进行MD5运算
/// </summary>
/// <param name="str"></param>
/// <returns></returns>
public static string GetMd5String(string str)
{
MD5 md5 = MD5.Create();
byte[] buffer = Encoding.UTF8.GetBytes(str);
byte[] md5Buffer = md5.ComputeHash(buffer);
StringBuilder sb = new StringBuilder();
foreach (byte b in md5Buffer)
{
sb.Append(b.ToString("x2"));
}
md5.Clear();
return sb.ToString();
}