自己写一个吧，很简单的。

http://topic.csdn.net/u/20090815/08/1AA82791-A7A2-4640-80B4-907F5771D676.html

sqlDALHelper  别人写的  

http://blog.csdn.net/anchenyanyue

贴几个我项目中用到的。

/// <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

/// <summary>
/// 消息提示类,简化页面消息提示
/// </summary>
public static class MessageBox
{
    const string javaScriptHead = "<script type='text/javascript'>";
    const string javaScriptFoot = "</script>";

    /// <summary>
    /// Page.ClientScript.RegisterStartupScript提示消息
    /// 注意:模版页中提示消息不能用此方法;消息中有换行用\\r\\n
    /// </summary>
    /// <remarks>
    /// MessageBox.Show("提示信息！",this);
    /// </remarks>
    /// <param name="message">提示信息</param>
    /// <param name="page">页面对象,一般传入this</param>
    public static void Show(string message, Page page)
    {
        Type pageType = page.GetType();
        page.ClientScript.RegisterStartupScript(pageType, pageType.Name, javaScriptHead + "alert('" + message.Replace("'", " ") + "')" + javaScriptFoot);
    }

    /// <summary>
    /// ScriptManager.RegisterStartupScript提示消息
    /// </summary>
    /// <param name="message">提示信息</param>
    /// <param name="updatePanel">UpdatePanel对象</param>
    public static void Show(string message, UpdatePanel updatePanel)
    {
        ScriptManager.RegisterStartupScript(updatePanel, updatePanel.Page.GetType(), updatePanel.ID, "alert('" + message.Replace("'", " ") + "');", true);
    }

    /// <summary>
    /// confirm确认提示消息后，跳转到指定页面，Page.ClientScript.RegisterStartupScript提示消息
    /// </summary>
    /// <remarks>
    /// MessageBox.ShowConfirmAndRedirect("提示消息！","Success.aspx",this);
    /// </remarks>
    /// <param name="message">提示消息</param>
    /// <param name="url">跳转的页面</param>
    /// <param name="page">页面对象,一般传入this</param>
    public static void ShowConfirmAndRedirect(string message, string url, Page page)
    {
        string script = "var ok=false;";

        if (!string.IsNullOrEmpty(message))
            script = "ok=confirm('" + message.Replace("'", " ") + "');";
        if (!string.IsNullOrEmpty(url))
            script += "if(ok==true)top.location.href='" + url + "'";

        script = javaScriptHead + script + javaScriptFoot;

        Type pageType = page.GetType();
        page.ClientScript.RegisterStartupScript(pageType, pageType.Name, script);
    }

    /// <summary>
    /// 提示消息后刷新指定父页面，Page.ClientScript.RegisterStartupScript提示消息
    /// </summary>
    /// <param name="message">提示消息</param>
    /// <param name="url">父窗口要跳转的页面</param>
    /// <param name="page">页面对象,一般传入this</param>
    public static void ShowAndRefreshParent(string message, string url, Page page)
    {
        string script = string.Empty;

        if (!string.IsNullOrEmpty(message))
            script = "alert('" + message.Replace("'", " ") + "');";
        if (!string.IsNullOrEmpty(url))
            script += "window.opener.location.href='" + url + "';window.close();";

        script = javaScriptHead + script + javaScriptFoot;

        Type pageType = page.GetType();
        page.ClientScript.RegisterStartupScript(pageType, pageType.Name, script);
    }

    /// <summary>
    /// window.open打开窗口
    /// </summary>
    /// <param name="url">要打开的页面</param>
    /// <param name="width">窗口宽度</param>
    /// <param name="height">窗口高度</param>
    /// <param name="page">页面对象,一般传入this</param>
    public static void OpenWindow(string url, int width, int height, Page page)
    {
        string script = javaScriptHead + "var newwindow=window.open('" + url + "','_blank','width=" + width + ",height=" + height
            + ",top='+(screen.height-" + height + ")/2+',left='+(screen.width-" + width
            + ")/2+',toolbar=no,menubar=no,scrollbars=yes,resizable=no,location=no,status=no');newwindow.focus();"
            + javaScriptFoot;

        Type pageType = page.GetType();
        page.ClientScript.RegisterStartupScript(pageType, pageType.Name, script);
    }

    /// <summary>
    /// 弹出居中模态窗口
    /// </summary>
    /// <param name="url">页面地址</param>
    /// <param name="width">模态窗口宽度</param>
    /// <param name="height">模态窗口高度</param>
    /// <param name="page">页面对象,一般传入this</param>
    public static void ShowModalDialog(string url, int width, int height, Page page)
    {
        string script = javaScriptHead + "window.showModalDialog('" + url + "','','dialogWidth:" + width + "px;dialogHeight:" + height
            + "px;dialogTop:'+(screen.height-" + height + ")/2+'px;dialogLeft:'+(screen.width-" + width
            + ")/2+'px;center:1;scroll:no;status:no;');" + javaScriptFoot;

        Type pageType = page.GetType();
        page.ClientScript.RegisterStartupScript(pageType, pageType.Name, script);
    }

    #region Response.Write 提示消息

    /// <summary>
    /// Response提示消息后跳转到指定页面
    /// window.location.href
    /// </summary>
    /// <param name="message">提示信息</param>
    /// <param name="url">跳转的页面</param>
    public static void ResponseMsgAndRedirect(string message, string url)
    {
        string script = string.Empty;

        if (!string.IsNullOrEmpty(message))
            script = "alert('" + message.Replace("'", " ") + "');";
        if (!string.IsNullOrEmpty(url))
            script += "window.location.href='" + url + "'";

        script = javaScriptHead + script + javaScriptFoot;

        System.Web.HttpContext.Current.Response.Write(script);
    }

    /// <summary>
    /// Response提示消息后，子页面触发父页面跳转，适用于iframe
    /// parent.location.href
    /// </summary>
    /// <param name="message">提示信息</param>
    /// <param name="url">要跳转页面</param>
    public static void ResponseMsgAndParentRedirect(string message, string url)
    {
        string script = string.Empty;

        if (!string.IsNullOrEmpty(message))
            script = "alert('" + message.Replace("'", " ") + "');";
        if (!string.IsNullOrEmpty(url))
            script += "parent.location.href='" + url + "'";

        script = javaScriptHead + script + javaScriptFoot;

        System.Web.HttpContext.Current.Response.Write(script);
    }

    /// <summary>
    /// Response提示消息后，最顶层的页面跳转，适用于iframe中子页面触发顶层页面跳转
    /// top.location.href
    /// </summary>
    /// <param name="message">提示信息</param>
    /// <param name="url">要跳转的页面</param>
    public static void ResponseMsgAndTopRedirect(string message, string url)
    {
        string script = string.Empty;

        if (!string.IsNullOrEmpty(message))
            script = "alert('" + message.Replace("'", " ") + "');";
        if (!string.IsNullOrEmpty(url))
            script += "top.location.href='" + url + "'";

        script = javaScriptHead + script + javaScriptFoot;

        System.Web.HttpContext.Current.Response.Write(script);
    }

    /// <summary>
    ///  Response提示消息后返回指定页面
    /// </summary>
    /// <param name="message">提示信息</param>
    /// <param name="historyCount">history.go(historyCount)</param>
    public static void ResponseMsgAndHistoryBack(string message, int historyCount)
    {
        string script = string.Empty;

        if (!string.IsNullOrEmpty(message))
            script = "alert('" + message.Replace("'", " ") + "');";

        script = javaScriptHead + script + "history.go(" + historyCount + ")" + javaScriptFoot;

        System.Web.HttpContext.Current.Response.Write(script);
    }
    #endregion
}

/// <summary>
/// 过滤xss攻击脚本
/// </summary>
public static class XSSFilter
{
    /// <summary>   
    /// 过滤xss攻击脚本   
    /// </summary>   
    /// <param name="html">传入字符串</param>   
    /// <returns>过滤后的字符串</returns>   
    public static string Filter(string html)
    {
        if (string.IsNullOrEmpty(html)) return string.Empty;
        // CR(0a) ，LF(0b) ，TAB(9) 除外，过滤掉所有的不打印出来字符.    
        // 目的防止这样形式的入侵 ＜java\0script＞   
        // 注意：\n, \r,  \t 可能需要单独处理，因为可能会要用到   
        string ret = System.Text.RegularExpressions.Regex.Replace(html, "([\x00-\x08][\x0b-\x0c][\x0e-\x20])", string.Empty);

        //替换所有可能的16进制构建的恶意代码   
        //<IMG SRC=&#X40&#X61&#X76&#X61&#X73&#X63&#X72&#X69&#X70&#X74&#X3A&#X61&_#X6C&#X65&#X72&#X74&#X28&#X27&#X58&#X53&#X53&#X27&#X29>   
        string chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*()~`;:?+/={}[]-_|'\"\\";
        for (int i = 0; i < chars.Length; i++)
        {
            ret = System.Text.RegularExpressions.Regex.Replace(ret, string.Concat("(&#[x|X]0{0,}", Convert.ToString((int)chars[i], 16).ToLower(), ";?)"),
                chars[i].ToString(), System.Text.RegularExpressions.RegexOptions.IgnoreCase);
        }

        //过滤\t, \n, \r构建的恶意代码  
        string[] keywords = {"javascript", "vbscript", "expression", "applet", "meta", "xml", "blink", 
                                "link", "style", "script","object", "iframe", "frame", // "embed", 
                                "frameset", "ilayer", "layer", "bgsound", "title", "base" ,"onabort",
                                "onactivate", "onafterprint", "onafterupdate", "onbeforeactivate", 
                                "onbeforecopy", "onbeforecut", "onbeforedeactivate",
                                "onbeforeeditfocus", "onbeforepaste", "onbeforeprint", "onbeforeunload", 
                                "onbeforeupdate", "onblur", "onbounce", "oncellchange", "onchange", 
                                "onclick", "oncontextmenu", "oncontrolselect", "oncopy", "oncut", 
                                "ondataavailable", "ondatasetchanged", "ondatasetcomplete", "ondblclick",
                                "ondeactivate", "ondrag", "ondragend", "ondragenter", "ondragleave",
                                "ondragover", "ondragstart", "ondrop", "onerror", "onerrorupdate",
                                "onfilterchange", "onfinish", "onfocus", "onfocusin", "onfocusout", 
                                "onhelp", "onkeydown", "onkeypress", "onkeyup", "onlayoutcomplete", 
                                "onload", "onlosecapture", "onmousedown", "onmouseenter", "onmouseleave", 
                                "onmousemove", "onmouseout", "onmouseover", "onmouseup", "onmousewheel",
                                "onmove", "onmoveend", "onmovestart", "onpaste", "onpropertychange", 
                                "onreadystatechange", "onreset", "onresize", "onresizeend", "onresizestart", 
                                "onrowenter", "onrowexit", "onrowsdelete", "onrowsinserted", "onscroll",
                                "onselect", "onselectionchange", "onselectstart", "onstart", "onstop",
                                "onsubmit", "onunload"};

        bool found = true;
        while (found)
        {
            var retBefore = ret;

            StringBuilder pattern = new StringBuilder(1000);
            StringBuilder pattern2 = new StringBuilder(1000);
            for (int i = 0; i < keywords.Length; i++)
            {
                pattern.Remove(0, pattern.Length);
                pattern.Append("<");
                pattern2.Remove(0, pattern2.Length);
                pattern2.Append("/");
                for (int j = 0; j < keywords[i].Length; j++)
                {
                    if (j > 0)
                    {
                        pattern.Append("((&#[x|X]0{0,8}([9][a][b]);?)?|(&#0{0,8}([9][10][13]);?)?)?");
                        pattern2.Append("((&#[x|X]0{0,8}([9][a][b]);?)?|(&#0{0,8}([9][10][13]);?)?)?");
                    }
                    pattern.Append(keywords[i][j]);
                    pattern2.Append(keywords[i][j]);
                }
                string replacement = string.Concat(keywords[i].Substring(0, 2), "＜x＞", keywords[i].Substring(2));
                ret = System.Text.RegularExpressions.Regex.Replace(ret, pattern.ToString(), replacement, System.Text.RegularExpressions.RegexOptions.IgnoreCase);
                ret = System.Text.RegularExpressions.Regex.Replace(ret, pattern2.ToString(), replacement, System.Text.RegularExpressions.RegexOptions.IgnoreCase);
                if (ret == retBefore)
                    found = false;
            }

        }
        return ret;
    }
}

slyzly,兄弟，你真给力。等会分多给你一点。

另一种，按照字节截取方式。

   public static string CutString(this string value, int length)

    {

        if (string.IsNullOrEmpty(value)) return "";



        int dataLength = length * 2;  //要截取的字节长度

        byte[] bLength = Encoding.GetEncoding("gb2312").GetBytes(value);  //原字符串的字节长度



        if (bLength.Length <= dataLength)

            return value;



        string strEndRes = "";

        while (true)

        {

            strEndRes += value.Substring(strEndRes.Length, length);



            int size = dataLength - Encoding.GetEncoding("gb2312").GetBytes(strEndRes).Length;

            if (size <= 1)

            {

                if (size == 1 && Encoding.GetEncoding("gb2312").GetBytes(value.Substring(strEndRes.Length, 1)).Length == 1)

                {

                    strEndRes += value.Substring(strEndRes.Length, 1);

                }

                return strEndRes;

            }

            length = size / 2;

        }

    }

之前做项目，导入了一堆的公共类，然后讲了一通，最后review发现，根本没人用~~~~
好伤心~~~~

这就是最悲剧的地方。。。 。。。

引用 10 楼  的回复:

之前做项目，导入了一堆的公共类，然后讲了一通，最后review发现，根本没人用~~~~
好伤心~~~~

 编译以后有差不多500kB，当然了不是给别人用的。