亮亮大伙儿常用的公共类吧

/// <summary>    /// 截取指定长度中英文字符串(宽度一样)    /// </summary>    /// <param name="str">要截取的字符串</param>    /// <param name="length">截取长度,中文字符长度</param>    /// <returns>截取后的字符串</returns>    public static string CutStr(object str, int length)    {        if (str == null) return string.Empty;        Encoding encoding = Encoding.GetEncoding("gb2312");        int len = length * 2;        int j = 0, k = 0;        string cutStr = str.ToString();        for (int i = 0; i < cutStr.Length; i++)        {            byte[] bytes = encoding.GetBytes(cutStr.Substring(i, 1));            if (bytes.Length == 2)//不是英文                j += 2;            else                j++;            if (j <= len)                k += 1;            if (j >= len)                return cutStr.Substring(0, k) + "...";        }        return cutStr;    }    /// <summary>    /// 下载指定路径文件    /// </summary>    /// <param name="path">文件绝对路径</param>    public static void DownLoadFile(string path)    {        System.IO.FileInfo fi = new System.IO.FileInfo(path);        if (fi.Exists)        {            //判断文件是否正在使用            try            {                using (System.IO.FileStream fs = System.IO.File.Open(path, System.IO.FileMode.Append, System.IO.FileAccess.Write, System.IO.FileShare.None))                {                }            }            catch (Exception ex)            {                throw;            }            System.Web.HttpContext.Current.Response.Clear();            System.Web.HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(path.Substring(path.LastIndexOf("\\") + 1), System.Text.Encoding.UTF8));            System.Web.HttpContext.Current.Response.AddHeader("Content-Length", fi.Length.ToString());            System.Web.HttpContext.Current.Response.ContentType = "application/octet-stream;charset=gb2321";            System.Web.HttpContext.Current.Response.WriteFile(fi.FullName);            System.Web.HttpContext.Current.Response.Flush();            System.Web.HttpContext.Current.Response.Close();        }        else        {            System.Web.HttpContext.Current.Response.Write("<script>alert('源文件不存在！');</script>");        }    }    /// <summary>    /// 获取枚举的描述信息    /// </summary>    /// <param name="en">枚举</param>    /// <returns></returns>    public static string GetEnumDescription(this Enum en)    {        Type type = en.GetType();        System.Reflection.MemberInfo[] memInfo = type.GetMember(en.ToString());        if (memInfo != null && memInfo.Length > 0)        {            object[] attrs = memInfo[0].GetCustomAttributes(typeof(System.ComponentModel.DescriptionAttribute), false);            if (attrs != null && attrs.Length > 0)                return ((System.ComponentModel.DescriptionAttribute)attrs[0]).Description;        }        return en.ToString();    }/// <summary>/// 通用应用程序缓存辅助类/// </summary>public static class CacheHelper{    public delegate T GetDataMethod<T>();//获取数据的方法    /// <summary>    /// 通用应用程序缓存方法,缓存数据10分钟    /// </summary>    /// <typeparam name="T">缓存数据的类型，一般是集合，如IList&lt;UsersData&gt;</typeparam>    /// <param name="key">键</param>    /// <param name="getDataMethod">获取数据的方法</param>    /// <returns>数据列表</returns>    public static T GetCache<T>(string key, GetDataMethod<T> getDataMethod)    {        //T dataList = getDataMethod();                //return dataList;        if (HttpRuntime.Cache[key] == null)        {            T dataList = getDataMethod();            HttpRuntime.Cache.Add(key, dataList, null, DateTime.Now.AddMinutes(10),                TimeSpan.Zero, System.Web.Caching.CacheItemPriority.High, null);            return dataList;        }        return (T)HttpRuntime.Cache[key];    }    /// <summary>    /// 移除应用程序缓存    /// </summary>    /// <param name="key">键</param>    public static void RemoveCacheByKey(string key)    {        HttpRuntime.Cache.Remove(key);    }}    /// <summary>     /// 获取用户IP地址    /// </summary>     public static string IPAddress    {        get        {            //string ipAddress = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];            //HTTP_X_FORWARDED_FOR获取的用户真实ip可能存在欺骗，所以忽略通过代理的访问的用户真实ip地址，记录代理ip            string ipAddress = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];            if (string.IsNullOrEmpty(ipAddress))                ipAddress = HttpContext.Current.Request.UserHostAddress;            if (ipAddress.Length > 15) //是ipv6格式ip，转换为ipv4            {                //取得客户端主机 IPv4 位址(通过DNS反查)                string ipv4 = string.Empty;                foreach (System.Net.IPAddress ip in System.Net.Dns.GetHostAddresses(ipAddress))                {                    if (ip.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)                    {                        ipv4 = ip.ToString();                        break;                    }                }                if (ipv4.Length == 0)                {                    foreach (System.Net.IPAddress ip2 in System.Net.Dns.GetHostEntry(ipAddress).AddressList)                    {                        if (ip2.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)                        {                            ipv4 = ip2.ToString();                            break;                        }                    }                }                return ipv4.Length > 0 ? ipv4 : string.Empty;            }            return ipAddress;        }    }    #region Cookie操作    /// <summary>    /// 设置指定Cookie名称的值    /// </summary>    /// <param name="cookieName">cookie名称</param>    /// <param name="cookieValue">值</param>    /// <param name="expires">过期时间，DateTime.MinValue表示默认过期时间</param>    public static void AddCookie(string cookieName, string cookieValue, DateTime expires)    {        HttpContext.Current.Response.Cookies[cookieName].Value = string.Empty;        HttpContext.Current.Response.Cookies[cookieName].Value = cookieValue;        if (expires != DateTime.MinValue)            HttpContext.Current.Response.Cookies[cookieName].Expires = expires;    }    /// <summary>    /// 读取指定cookie名称的值    /// </summary>    /// <param name="cookieName">cookie名称</param>    /// <returns>值</returns>    public static string GetCookie(string cookieName)    {        string cookieValue = string.Empty;        try        {            cookieValue = HttpContext.Current.Request.Cookies[cookieName].Value;        }        catch { }        return cookieValue;    }    /// <summary>    /// 删除指定名称cookie    /// </summary>    /// <param name="cookieName">cookie名称</param>    public static void RemoveCookie(string cookieName)    {        HttpContext.Current.Response.Cookies[cookieName].Expires = DateTime.MinValue;    }    #endregion