.NET开发中你可能会用到的常用方法总结

学习.NET有一些时间了，平日积累了一些自己认为比较实用的方法（有自己写的，也有学习别人的），可能会在不同的项目开发中使用到。分享给大家，有什么好的方法还会不断添加，个别方法你可能认为很菜，仅提供给新手。当然，实现功能的方法并不唯一，这里仅供大家参考。

将文件转换成字符串,常用于读取网站模板

/// <summary>
    /// 将文件转换成字符串,常用于读取网站模板
    /// </summary>
    /// <param name="path"></param>
    /// <param name="isSpace"></param>
    /// <returns></returns>
     public static string GetTempleContent(string path)
    {
        string result = string.Empty;
        string sFileName = HttpContext.Current.Server.MapPath(path);
        if (File.Exists(sFileName))
        {
            try
            {
                using (StreamReader sr = new StreamReader(sFileName))
                {
                    result = sr.ReadToEnd();
                }
            }
            catch
            {
                result = "读取模板文件(" + path + ")出错";
            }
        }
        else
        {
            result = "找不到模板文件：" + path;
        }
        return result;
    }

读取,添加，修改xml文件

Code
/// <summary>
    /// 读取,添加，修改xml文件
    /// </summary>
    /// <param name="Xmlpath">Xml路径</param>
    /// <param name="Node">新的子节点名称</param>
    /// <param name="Value">新节点对应的值</param>
    /// <param name="flag">1：读取，否则为 修改或者添加</param>
    /// <returns>1：修改添加成功，为空字符串表示修改添加成功，否则是读取成功</returns>
    public static string getXML(string Xmlpath, string Node, string Value, int flag)
    {
        try
        {
            string filepath = HttpContext.Current.Server.MapPath(Xmlpath);
            XmlDocument xmlDoc = new XmlDocument();
            if (!File.Exists(filepath))
            {
                XmlDeclaration xn = xmlDoc.CreateXmlDeclaration("1.0", "utf-8", null);
                XmlElement root = xmlDoc.CreateElement("rss");
                XmlElement root1 = xmlDoc.CreateElement("item");

                root.AppendChild(root1);
                xmlDoc.AppendChild(xn);
                xmlDoc.AppendChild(root);
                xmlDoc.Save(filepath);//本地路径名字
            }
            xmlDoc.Load(filepath);//你的xml文件
            string ReStr = string.Empty;
            XmlElement xmlObj = xmlDoc.DocumentElement;

            XmlNodeList xmlList = xmlDoc.SelectSingleNode(xmlObj.Name.ToString()).ChildNodes;

            foreach (XmlNode xmlNo in xmlList)
            {
                if (xmlNo.NodeType != XmlNodeType.Comment)//判断是不是注释类型
                {
                    XmlElement xe = (XmlElement)xmlNo;
                    {
                        if (xe.Name == xmlObj.FirstChild.Name)
                        {
                            XmlNodeList xmlNList = xmlObj.FirstChild.ChildNodes;

                            foreach (XmlNode xmld in xmlNList)
                            {
                                XmlElement xe1 = (XmlElement)xmld;
                                {
                                    if (xe1.Name == Node)
                                    {
                                        if (flag == 1)//读取值
                                        {
                                            if (xmld.InnerText != null && xmld.InnerText != "")
                                            {
                                                ReStr = xmld.InnerText;
                                            }
                                        }
                                        else//修改值
                                        {
                                            xmld.InnerText = Value;//给节点赋值
                                            xmlDoc.Save(filepath);
                                            ReStr = Value.Trim();
                                        }
                                    }
                                }
                            }
                            if (ReStr == string.Empty)// 添加节点
                            {
                                XmlNode newNode;
                                newNode = xmlDoc.CreateNode("element", Node, Value);//创建节点
                                newNode.InnerText = Value;//给节点赋值
                                xe.AppendChild(newNode);//把节点添加到doc
                                xmlDoc.Save(filepath);
                                ReStr = Value.Trim();
                            }
                        }
                    }
                }
            }
            return ReStr;
        }
        catch
        {
            return string.Empty;
        }
    }

取得文件扩展名

Code
/// <summary>
    /// 取得文件扩展名
    /// </summary>
    /// <param name="filename">文件名</param>
    /// <returns>扩展名</returns>
    public static string GetFileEXT(string filename)
    {
        if (string.IsNullOrEmpty(filename))
        {
            return "";
        }
        if (filename.IndexOf(@".") == -1)
        {
            return "";
        }
        int pos = -1;
        if (!(filename.IndexOf(@"\") == -1))
        {
            pos = filename.LastIndexOf(@"\");
        }
        string[] s = filename.Substring(pos + 1).Split('.');
        return s[1];
    }

替换文本中的空格和换行

Code
/// <summary>
    /// 替换文本中的空格和换行
    /// </summary>
    public static string ReplaceSpace(string str)
    {
        string s = str;
        s = s.Replace(" ", "&nbsp;");
        s = s.Replace("\n", "<BR />");
        return s;
    }

验证码实现方法

Code
    protected void Page_Load(object sender, EventArgs e)
    {
         string checkCode = CreateRandomCode(4);
          Session["CheckCode"] = checkCode;
          CreateImage(checkCode);
    }
     private string CreateRandomCode(int codeCount)
    {

        // 函数功能:产生数字和字符混合的随机字符串
        string allChar = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
        char[] allCharArray = allChar.ToCharArray();
        string randomCode = "";
        Random rand = new Random();
        for (int i = 0; i < codeCount; i++)
        {
           int r=rand.Next(61);
           randomCode+=allCharArray.GetValue(r);
        }
         return randomCode;
        
     }
         

    private void CreateImage(string checkCode)
    {

        // 生成图象验证码函数
       int iwidth = (int)(checkCode.Length * 11.5);
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 20);
        Graphics g = Graphics.FromImage(image);
        Font f = new System.Drawing.Font("Arial", 10, System.Drawing.FontStyle.Bold);
        Brush b = new System.Drawing.SolidBrush(Color.Azure);//字母白色
        //g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height);
        g.Clear(Color.Brown);//背景灰色
        g.DrawString(checkCode, f, b, 3, 3);

        Pen blackPen = new Pen(Color.Black, 0);
        Random rand = new Random();
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
        Response.ClearContent();
        Response.ContentType = "image/Jpeg";
        Response.BinaryWrite(ms.ToArray());
        g.Dispose();
        image.Dispose();
    }

文件创建、复制、移动、删除

Code
FileStream fs;
 //创建文件
 fs = File.Create(Server.MapPath("a.txt"));
 fs.Close();
 fs = File.Create(Server.MapPath("b.txt"));
 fs.Close();
 fs = File.Create(Server.MapPath("c.txt"));
 fs.Close();
 //复制文件
 File.Copy(Server.MapPath("a.txt"), Server.MapPath("a\\a.txt"));
 //移动文件
 File.Move(Server.MapPath("b.txt"), Server.MapPath("a\\b.txt"));
 File.Move(Server.MapPath("c.txt"), Server.MapPath("a\\c.txt"));
 //删除文件
 File.Delete(Server.MapPath("a.txt"));

去掉结尾，

Code
/// <summary>
    /// 去掉结尾，
    /// </summary>
    /// <param name="input"></param>
    /// <returns></returns>
    public static string LostDot(string input)
    {
        if (string.IsNullOrEmpty(input))
        {
            return string.Empty;
        }
        else
        {
            if (input.IndexOf(",") > -1)
            {
                int intLast = input.LastIndexOf(",");
                if ((intLast + 1) == input.Length)
                {
                    return input.Remove(intLast);
                }
                else
                {
                    return input;
                }
            }
            else
            {
                return input;
            }
        }
    }

生成任意位数的随机数

Code
/// <summary>
    /// 生成随机数
    /// </summary>
    /// <param name="minValue">最小值</param>
    /// <param name="maxValue">最大值</param>
    /// <returns></returns>
    private int getRandom(int minValue, int maxValue)
    {
        Random ri = new Random(unchecked((int)DateTime.Now.Ticks));
        int k = ri.Next(minValue, maxValue);
        return k;
    }

//想定一个三位的随机数：string ThreeRandom=this.getRandom(100,999).Tostring();
//类似的，四位随机数：string FourRandom=this.getRandom(1000,9999).Tostring();

实现文件的上传

Code
public class Upload
    {
        private System.Web.HttpPostedFile postedFile = null;
        private string savePath = "";
        private string extension = "";
        private int fileLength = 0;
        private string filename = "";
        /// <summary>
        /// 上传组件
        /// </summary>
        public System.Web.HttpPostedFile PostedFile
        {
            get
            {
                return postedFile;
            }
            set
            {
                postedFile = value;
            }
        }
        /// <summary>
        /// 保存路径
        /// </summary>
        public string SavePath
        {
            get
            {
                if (savePath != "") return savePath;
                return "c:\\";
            }
            set
            {
                savePath = value;
            }
        }
        /// <summary>
        /// 文件大小
        /// </summary>
        public int FileLength
        {
            get
            {
                if (fileLength != 0) return fileLength;
                return 1024;
            }
            set
            {
                fileLength = value * 1024;
            }
        }
        /// <summary>
        /// 文件护展名
        /// </summary>
        public string Extension
        {
            get
            {
                if (extension != "")
                    return extension;
                return "txt";
            }
            set
            {
                extension = value;
            }
        }
        /// <summary>
        /// 文件名
        /// </summary>
        public string FileName
        {
            get
            {
                return filename;
            }
            set
            {
                filename = value;
            }
        }
        public string PathToName(string path)
        {
            int pos = path.LastIndexOf(@"\");
            return path.Substring(pos + 1);
        }
        /// <summary>
        /// 上传文件
        /// </summary>
        /// <returns></returns>
        public string UploadStart()
        {
            bool tf = false;
            string returnvalue = "";
            if (PostedFile != null)
            {
                try
                {
                    string fileName = PathToName(PostedFile.FileName);
                    if (filename != "")
                    {
                        fileName = filename;
                    }
                    string _fileName = "";

                    string[] Exten = Extension.Split(',');
                    if (Exten.Length == 0)
                    {
                        returnvalue = "你未设置上传文件类型,系统不允许进行下一步操作!";
                    }
                    else
                    {
                        for (int i = 0; i < Exten.Length; i++)
                        {
                            if (fileName.ToLower().EndsWith(Exten[i].ToLower()))
                            {
                                if (PostedFile.ContentLength > FileLength)
                                {
                                    returnvalue = "上传文件限制大小:" + FileLength / 1024 + "kb!";
                                }
                                string IsFileex = SavePath + @"\" + fileName;
                                if (!Directory.Exists(SavePath)) { Directory.CreateDirectory(SavePath); }
                                PostedFile.SaveAs(IsFileex);
                                _fileName = fileName;
                                tf = true;
                                returnvalue = IsFileex ;
                            }
                        }
                        if (tf == false)
                            returnvalue = "只允许上传" + Extension + " 文件!";
                    }
                }
                catch (System.Exception exc)
                {
                    returnvalue = exc.Message;
                }
            }
            else
            {
                returnvalue = "上文件失败!";
            }
            return returnvalue;
        }
    }

判断输入是否为日期类型

Code
 /// <summary>
        /// 判断输入是否为日期类型
        /// </summary>
        /// <param name="s">待检查数据</param>
        /// <returns></returns>
        public static bool IsDate(string s)
        {
            if (s == null)
            {
                return false;
            }
            else
            {
                try
                {
                    DateTime d = DateTime.Parse(s);
                    return true;
                }
                catch
                {
                    return false;
                }
            }
        }

MD5加密字符串处理

Code
/// <summary>
        /// MD5加密字符串处理
        /// </summary>
        /// <param name="Half">加密是16位还是32位；如果为true为16位</param>
        public static string MD5(string Input, bool Half)
        {
            string output = System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(Input, "MD5").ToLower();
            if (Half) output = output.Substring(8, 16);
            return output;
        }

        public static string MD5(string Input)
        {
            return MD5(Input, true);
        }

过滤非法字符，防止注入式攻击等

Code
/// <summary>
        /// 过滤字符
        /// </summary>
        public static string Filter(string sInput)
        {
            if (sInput == null || sInput.Trim() == string.Empty)
                return null;
            string sInput1 = sInput.ToLower();
            string output = sInput;
            string pattern = @"*|and|exec|insert|select|delete|update|count|master|truncate|declare|char(|mid(|chr(|'";
            if (Regex.Match(sInput1, Regex.Escape(pattern), RegexOptions.Compiled | RegexOptions.IgnoreCase).Success)
            {
                throw new Exception("字符串中含有非法字符!");
            }
            else
            {
                output = output.Replace("'", "''");
            }
            return output;
        }

常用的加密解密（DES，RSA）

Code
    using System.Security.Cryptography;
using System.Text;

    /// <summary>
    /// DES加密
    /// </summary>
    /// <param name="input">待加密的字符串</param>
    /// <param name="key">加密密钥</param>
    /// <returns></returns>
    public static string Encrypt(string EncryptString, byte[] Key, byte[] IV)
    {
        //byte[] rgbKey = Encoding.UTF8.GetBytes(key.Substring(0, 8));
        byte[] inputByteArray = Encoding.UTF8.GetBytes(EncryptString);
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();
        MemoryStream mStream = new MemoryStream();
        CryptoStream cStream = new CryptoStream(mStream, des.CreateEncryptor(Key, IV), CryptoStreamMode.Write);
        cStream.Write(inputByteArray, 0, inputByteArray.Length);
        cStream.FlushFinalBlock();
        return Convert.ToBase64String(mStream.ToArray());
    }
    /// <summary>
    /// DES解密
    /// </summary>
    /// <param name="input">待解密的字符串</param>
    /// <param name="key">解密密钥,要求为8位,和加密密钥相同</param>
    /// <returns>解密成功返回解密后的字符串,失败返源串</returns>
    public static string Decrypt(string DecryptString, byte[] Key, byte[] IV)
    {
        try
        {
            //byte[] rgbKey = Encoding.UTF8.GetBytes(Key);
            byte[] inputByteArray = Convert.FromBase64String(DecryptString);
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();

            MemoryStream mStream = new MemoryStream();
            CryptoStream cStream = new CryptoStream(mStream, des.CreateDecryptor(Key, IV), CryptoStreamMode.Write);
            cStream.Write(inputByteArray, 0, inputByteArray.Length);
            cStream.FlushFinalBlock();
            return Encoding.UTF8.GetString(mStream.ToArray());
        }
        catch
        {
            return "";
        }
    }
}
/// <summary>
/// RSA加解密算法
/// </summary>
public class RSA
{
    /// <summary>
    /// RSA加密函数
    /// </summary>
    /// <param name="xmlPublicKey">说明KEY必须是XML的行式,返回的是字符串</param>
    /// <param name="EncryptString"></param>
    /// <returns></returns>
    public string Encrypt(string xmlPublicKey, string EncryptString)
    {
        byte[] PlainTextBArray;
        byte[] CypherTextBArray;
        string Result;
        RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
        rsa.FromXmlString(xmlPublicKey);
        PlainTextBArray = (new UnicodeEncoding()).GetBytes(EncryptString);
        CypherTextBArray = rsa.Encrypt(PlainTextBArray, false);
        Result = Convert.ToBase64String(CypherTextBArray);
        return Result;
    }
    /// <summary>
    /// RSA解密函数
    /// </summary>
    /// <param name="xmlPrivateKey"></param>
    /// <param name="DecryptString"></param>
    /// <returns></returns>
    public string Decrypt(string xmlPrivateKey, string DecryptString)
    {
        byte[] PlainTextBArray;
        byte[] DypherTextBArray;
        string Result;
        RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
        rsa.FromXmlString(xmlPrivateKey);
        PlainTextBArray = Convert.FromBase64String(DecryptString);
        DypherTextBArray = rsa.Decrypt(PlainTextBArray, false);
        Result = (new UnicodeEncoding()).GetString(DypherTextBArray);
        return Result;
    }

    /// <summary>
    /// 产生RSA的密钥
    /// </summary>
    /// <param name="xmlKeys">私钥</param>
    /// <param name="xmlPublicKey">公钥</param>
    public void RSAKey(out string xmlKeys, out string xmlPublicKey)
    {
        RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
        xmlKeys = rsa.ToXmlString(true);
        xmlPublicKey = rsa.ToXmlString(false);
    }

写入读取Cookie值

Code
/// <summary>
        /// 写cookie值
        /// </summary>
        /// <param name="strName">名称</param>
        /// <param name="strValue">值</param>
        /// <param name="strValue">过期时间(分钟)</param>
        public static void WriteCookie(string strName, string strValue, int expires)
        {
            HttpCookie cookie = HttpContext.Current.Request.Cookies[strName];
            if (cookie == null)
            {
                cookie = new HttpCookie(strName);
            }
            cookie.Value = strValue;
            cookie.Expires = DateTime.Now.AddMinutes(expires);
            HttpContext.Current.Response.AppendCookie(cookie);
        }
        /// <summary>
        /// 读cookie值
        /// </summary>
        /// <param name="strName">名称</param>
        /// <returns>cookie值</returns>
        public static string GetCookie(string strName)
        {
            if (HttpContext.Current.Request.Cookies != null && HttpContext.Current.Request.Cookies[strName] != null)
            {
                return HttpContext.Current.Request.Cookies[strName].Value.ToString();
            }
            return "";
        }

读取配置文件的节点内容

Code
/// <summary>
        /// 读取配置文件
        /// </summary>
        /// <param name="Target"></param>
        /// <param name="ConfigPathName"></param>
        /// <returns></returns>
        static internal string GetConfigValue(string Target, string XmlPath)
        {
            System.Xml.XmlDocument xdoc = new XmlDocument();
            xdoc.Load(XmlPath);
            XmlElement root = xdoc.DocumentElement;
            XmlNodeList elemList = root.GetElementsByTagName(Target);
            return elemList[0].InnerXml;
        }

取单个字符的拼音声母

Code
/// <summary> 
        /// 取单个字符的拼音声母 
        /// </summary> 
        /// <param name="c">要转换的单个汉字</param> 
        /// <returns>拼音声母</returns> 
        private static string GetPYChar(string c)
        {
            byte[] array = new byte[2];
            array = System.Text.Encoding.Default.GetBytes(c);
            int i = (short)(array[0] - '\0') * 256 + ((short)(array[1] - '\0'));
            if (i < 0xB0A1) return "*";
            if (i < 0xB0C5) return "A";
            if (i < 0xB2C1) return "B";
            if (i < 0xB4EE) return "C";
            if (i < 0xB6EA) return "D";
            if (i < 0xB7A2) return "E";
            if (i < 0xB8C1) return "F";
            if (i < 0xB9FE) return "G";
            if (i < 0xBBF7) return "H";
            if (i < 0xBFA6) return "G";
            if (i < 0xC0AC) return "K";
            if (i < 0xC2E8) return "L";
            if (i < 0xC4C3) return "M";
            if (i < 0xC5B6) return "N";
            if (i < 0xC5BE) return "O";
            if (i < 0xC6DA) return "P";
            if (i < 0xC8BB) return "Q";
            if (i < 0xC8F6) return "R";
            if (i < 0xCBFA) return "S";
            if (i < 0xCDDA) return "T";
            if (i < 0xCEF4) return "W";
            if (i < 0xD1B9) return "X";
            if (i < 0xD4D1) return "Y";
            if (i < 0xD7FA) return "Z";
            return "*";
        }

变量.ToString()

Code
   //字符型转换 转为字符串  
   12345.ToString("n");        //生成   12,345.00  
   12345.ToString("C");        //生成 ￥12,345.00  
   12345.ToString("e");        //生成 1.234500e+004  
   12345.ToString("f4");        //生成 12345.0000  
   12345.ToString("x");         //生成 3039  (16进制)  
   12345.ToString("p");         //生成 1,234,500.00%  

时间的处理

Code
DateTime dt = DateTime.Now;
Label1.Text = dt.ToString();//2005-11-5 13:21:25
Label2.Text = dt.ToFileTime().ToString();//127756416859912816
Label3.Text = dt.ToFileTimeUtc().ToString();//127756704859912816
Label4.Text = dt.ToLocalTime().ToString();//2005-11-5 21:21:25
Label5.Text = dt.ToLongDateString().ToString();//2005年11月5日
Label6.Text = dt.ToLongTimeString().ToString();//13:21:25
Label7.Text = dt.ToOADate().ToString();//38661.5565508218
Label8.Text = dt.ToShortDateString().ToString();//2005-11-5
Label9.Text = dt.ToShortTimeString().ToString();//13:21
Label10.Text = dt.ToUniversalTime().ToString();//2005-11-5 5:21:25
?2005-11-5 13:30:28.4412864
Label1.Text = dt.Year.ToString();//2005
Label2.Text = dt.Date.ToString();//2005-11-5 0:00:00
Label3.Text = dt.DayOfWeek.ToString();//Saturday
Label4.Text = dt.DayOfYear.ToString();//309
Label5.Text = dt.Hour.ToString();//13
Label6.Text = dt.Millisecond.ToString();//441
Label7.Text = dt.Minute.ToString();//30
Label8.Text = dt.Month.ToString();//11
Label9.Text = dt.Second.ToString();//28
Label10.Text = dt.Ticks.ToString();//632667942284412864
Label11.Text = dt.TimeOfDay.ToString();//13:30:28.4412864
Label1.Text = dt.ToString();//2005-11-5 13:47:04
Label2.Text = dt.AddYears(1).ToString();//2006-11-5 13:47:04
Label3.Text = dt.AddDays(1.1).ToString();//2005-11-6 16:11:04
Label4.Text = dt.AddHours(1.1).ToString();//2005-11-5 14:53:04
Label5.Text = dt.AddMilliseconds(1.1).ToString();//2005-11-5 13:47:04
Label6.Text = dt.AddMonths(1).ToString();//2005-12-5 13:47:04
Label7.Text = dt.AddSeconds(1.1).ToString();//2005-11-5 13:47:05
Label8.Text = dt.AddMinutes(1.1).ToString();//2005-11-5 13:48:10
Label9.Text = dt.AddTicks(1000).ToString();//2005-11-5 13:47:04
Label10.Text = dt.CompareTo(dt).ToString();//0
//Label11.Text = dt.Add(?).ToString();//问号为一个时间段
Label1.Text = dt.Equals("2005-11-6 16:11:04").ToString();//False
Label2.Text = dt.Equals(dt).ToString();//True
Label3.Text = dt.GetHashCode().ToString();//1474088234
Label4.Text = dt.GetType().ToString();//System.DateTime
Label5.Text = dt.GetTypeCode().ToString();//DateTime

Label1.Text = dt.GetDateTimeFormats('s')[0].ToString();//2005-11-05T14:06:25
Label2.Text = dt.GetDateTimeFormats('t')[0].ToString();//14:06
Label3.Text = dt.GetDateTimeFormats('y')[0].ToString();//2005年11月
Label4.Text = dt.GetDateTimeFormats('D')[0].ToString();//2005年11月5日
Label5.Text = dt.GetDateTimeFormats('D')[1].ToString();//2005 11 05
Label6.Text = dt.GetDateTimeFormats('D')[2].ToString();//星期六 2005 11 05
Label7.Text = dt.GetDateTimeFormats('D')[3].ToString();//星期六 2005年11月5日
Label8.Text = dt.GetDateTimeFormats('M')[0].ToString();//11月5日
Label9.Text = dt.GetDateTimeFormats('f')[0].ToString();//2005年11月5日 14:06
Label10.Text = dt.GetDateTimeFormats('g')[0].ToString();//2005-11-5 14:06
Label11.Text = dt.GetDateTimeFormats('r')[0].ToString();//Sat, 05 Nov 2005 14:06:25 GMT

Label1.Text =? string.Format("{0:d}",dt);//2005-11-5
Label2.Text =? string.Format("{0:D}",dt);//2005年11月5日
Label3.Text =? string.Format("{0:f}",dt);//2005年11月5日 14:23
Label4.Text =? string.Format("{0:F}",dt);//2005年11月5日 14:23:23
Label5.Text =? string.Format("{0:g}",dt);//2005-11-5 14:23
Label6.Text =? string.Format("{0:G}",dt);//2005-11-5 14:23:23
Label7.Text =? string.Format("{0:M}",dt);//11月5日
Label8.Text =? string.Format("{0:R}",dt);//Sat, 05 Nov 2005 14:23:23 GMT
Label9.Text =? string.Format("{0:s}",dt);//2005-11-05T14:23:23
Label10.Text = string.Format("{0:t}",dt);//14:23
Label11.Text = string.Format("{0:T}",dt);//14:23:23
Label12.Text = string.Format("{0:u}",dt);//2005-11-05 14:23:23Z
Label13.Text = string.Format("{0:U}",dt);//2005年11月5日 6:23:23
Label14.Text = string.Format("{0:Y}",dt);//2005年11月
Label15.Text = string.Format("{0}",dt);//2005-11-5 14:23:23?
Label16.Text = string.Format("{0:yyyyMMddHHmmssffff}",dt); //yyyymm等可以设置,比如Label16.Text = string.Format("{0:yyyyMMdd}",dt);

获得ip和mac地址

Code
using System.Runtime.InteropServices;

[DllImport("Iphlpapi.dll")]
    private static extern int SendARP(Int32 dest, Int32 host, ref Int64 mac, ref Int32 length);
    [DllImport("Ws2_32.dll")]
    private static extern Int32 inet_addr(string ip);
    protected void Page_Load(object sender, EventArgs e)
    {
        
        // 在此处放置用户代码以初始化页面
        try
        {
            string userip = Request.UserHostAddress;
            string strClientIP = Request.UserHostAddress.ToString().Trim();
            Int32 ldest = inet_addr(strClientIP); //目的地的ip 
            Int32 lhost = inet_addr("");   //本地服务器的ip 
            Int64 macinfo = new Int64();
            Int32 len = 6;
            int res = SendARP(ldest, 0, ref macinfo, ref len);
            string mac_src = macinfo.ToString("X");
            if (mac_src == "0")
            {
                if (userip == "127.0.0.1")
                    Response.Write("正在访问Localhost!");
                else
                    Response.Write("欢迎来自IP为" + userip + "的朋友！" + "<br>");
                return;
            }

            while (mac_src.Length < 12)
            {
                mac_src = mac_src.Insert(0, "0");
            }

            string mac_dest = "";

            for (int i = 0; i < 11; i++)
            {
                if (0 == (i % 2))
                {
                    if (i == 10)
                    {
                        mac_dest = mac_dest.Insert(0, mac_src.Substring(i, 2));
                    }
                    else
                    {
                        mac_dest = "-" + mac_dest.Insert(0, mac_src.Substring(i, 2));
                    }
                }
            }

            Response.Write("欢迎来自IP为" + userip + "<br>" + ",MAC地址为" + mac_dest + "的朋友！"

             + "<br>");
        }
        catch (Exception err)
        {
            Response.Write(err.Message);
        }
    }


    private string GetClientIP()
    {
        string result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
        if (null == result || result == String.Empty)
        {
            result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
        } if (null == result || result == String.Empty)
        {
            result = HttpContext.Current.Request.UserHostAddress;
        }
        return result;
    }

调用Win32 Api函数，非托管DLL

Code
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
namespace NetMeeting.API
{
　　public class Win32
　　{
　　　　[DllImport("user32.dll", EntryPoint = "MessageBox", ExactSpelling = false)]
　　　　public static extern int MessageBox(int hWnd, string text, string caption, uint type);
　　}
}
//客户调用:

using System;
using NetMeeting.API;
class test
{
　　public static void Main(string[] agrs)
　　{
　　　　　　Win32.MessageBox(0,"hello ,this is a c# invoke win32 api","test",2);
　　}
}

生成高质量缩略图

Code
//方法1
public static Bitmap CreateThumbnail(Bitmap source, int thumbWi, int thumbHi, bool maintainAspect)
        {
            // return the source image if it's smaller than the designated thumbnail
            if (source.Width < thumbWi && source.Height < thumbHi) return source;

            System.Drawing.Bitmap ret = null;
            try
            {
                int wi, hi;

                wi = thumbWi;
                hi = thumbHi;

                if (maintainAspect)
                {
                    // maintain the aspect ratio despite the thumbnail size parameters
                    if (source.Width > source.Height)
                    {
                        wi = thumbWi;
                        hi = (int)(source.Height * ((decimal)thumbWi / source.Width));
                    }
                    else
                    {
                        hi = thumbHi;
                        wi = (int)(source.Width * ((decimal)thumbHi / source.Height));
                    }
                }

                // original code that creates lousy thumbnails
                // System.Drawing.Image ret = source.GetThumbnailImage(wi,hi,null,IntPtr.Zero);
                ret = new Bitmap(wi, hi);
                using (Graphics g = Graphics.FromImage(ret))
                {
                    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                    g.FillRectangle(Brushes.White, 0, 0, wi, hi);
                    g.DrawImage(source, 0, 0, wi, hi);
                }
            }
            catch
            {
                ret = null;
            }

            return ret;
        }
//调用
 using (Graphics g = Graphics.FromImage(ret))
                {
                    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                    g.FillRectangle(Brushes.White, 0, 0, wi, hi);
                    g.DrawImage(source, 0, 0, wi, hi);
                }

将文件保存到数据库中

Code
//保存文件到SQL Server数据库中
    private void FileToSql(string fileName,string tableName,string fieldName)
    {
        SqlConnection cn=new SqlConnection ();
        FileInfo fi=new FileInfo(fileName);
        FileStream fs=fi.OpenRead();
        byte[] bytes=new byte[fs.Length];
        fs.Read(bytes,0,Convert.ToInt32(fs.Length));
        SqlCommand cm=new SqlCommand();
        cm.Connection=cn;
        cm.CommandType=CommandType.Text;
        if(cn.State==0) cn.Open();
        cm.CommandText="insert into "+tableName+"("+fieldName+") values(@file)";
        SqlParameter spFile=new SqlParameter("@file",SqlDbType.Image);
        spFile.Value=bytes;
        cm.Parameters.Add(spFile);
        cm.ExecuteNonQuery();
    }
//保存文件到Access数据库中
    private void FileToAccess(string fileName,string tableName,string fieldName)
    {
        OleDbConnection cn=new OleDbConnection ();
        FileInfo fi=new FileInfo(fileName);
        FileStream fs=fi.OpenRead();
        byte[] bytes=new byte[fs.Length];
        fs.Read(bytes,0,Convert.ToInt32(fs.Length));
        OleDbCommand cm=new OleDbCommand();
        cm.Connection=cn;
        cm.CommandType=CommandType.Text;
        if(cn.State==0) cn.Open();
        cm.CommandText="insert into "+tableName+"("+fieldName+") values(@file)";
        OleDbParameter spFile=new OleDbParameter("@file",OleDbType.Binary);
        spFile.Value=bytes;
        cm.Parameters.Add(spFile);
        cm.ExecuteNonQuery();
    }
    //保存客户端文件到数据库,fl_name为上传控件
    private void FileToDataSourse(string mailid)
    {
        string ConnStr = "";
        string sql = "update t_mail set attachfilename=@attachfilename,attachfile=@attachfile where mailid=" + mailid;
        SqlCommand myCommand = new SqlCommand(sql, new SqlConnection(ConnStr));
        string path = fl_name.PostedFile.FileName;
        string filename = path.Substring(path.LastIndexOf("") + 1, path.Length - path.LastIndexOf("") - 1);
        myCommand.Parameters.Add("@attachfilename", SqlDbType.VarChar);
        myCommand.Parameters["@attachfilename"].Value = filename;
        myCommand.Parameters.Add("@attachfile", SqlDbType.Image);
        Stream fileStream = fl_name.PostedFile.InputStream;
        int intFileSize = fl_name.PostedFile.ContentLength;
        byte[] fileContent = new byte[intFileSize];
        int intStatus = fileStream.Read(fileContent, 0, intFileSize); //文件读取到fileContent数组中
        myCommand.Parameters["@attachfile"].Value = ((byte[])fileContent);
        fileStream.Close();
        myCommand.Connection.Open();
        myCommand.ExecuteNonQuery();
        myCommand.Connection.Close();
    }

将用户输入的字符串转换为可换行、替换Html编码、无危害数据库特殊字符、去掉首尾空白、的安全方便代码

Code
public static string ConvertStr(string inputString)
        {
            string retVal = inputString;
            retVal = retVal.Replace("&", "&amp;");
            retVal = retVal.Replace("\"", "&quot;");
            retVal = retVal.Replace("<", "&lt;");
            retVal = retVal.Replace(">", "&gt;");
            retVal = retVal.Replace(" ", "&nbsp;");
            retVal = retVal.Replace("  ", "&nbsp;&nbsp;");
            retVal = retVal.Replace("\t", "&nbsp;&nbsp;");
            retVal = retVal.Replace("\r", "<br>");
            return retVal;
        }

        private static string FetchURL(string strMessage)
        {
            string strPattern = @"(?<url>(http|ftp|mms|rstp|news|https)://(?:[\w-]+\.)+[\w-]+(?:/[\w-./?%&~=]*[^.\s|,|\)|<|!])?)";
            string strReplace = "<a href=\"${url}\" target=_blank>${url}</a>";
            string strInput = strMessage;
            string strResult;
            strResult = Regex.Replace(strInput, strPattern, strReplace);
            strPattern = @"(?<!http://)(?<url>www\.(?:[\w-]+\.)+[\w-]+(?:/[\w-./?%&~=]*[^.\s|,|\)|<|!])?)";
            strReplace = "<a href=\"http://${url}\" target=_blank>${url}</a>";
            strResult = Regex.Replace(strResult, strPattern, strReplace);
            return strResult;
        } 

        public string ToUrl(string inputString)
        {
            string retVal = inputString;
            retVal = ConvertStr(retVal);
            retVal = FetchURL(retVal);
            return retVal;
        }

ASP.NET获取服务器信息方法

if (!IsPostBack)
            {
                Label1.Text = "服务器名称："+Server.MachineName;//服务器名称
                Label2.Text = "服务器IP地址：" + Request.ServerVariables["LOCAL_ADDR"];//服务器IP地址
                Label3.Text = "服务器域名：" + Request.ServerVariables["SERVER_NAME"];//服务器域名
                Label4.Text = ".NET解释引擎版本：" + ".NET CLR" + Environment.Version.Major + "." + Environment.Version.Minor + "." + Environment.Version.Build + "." + Environment.Version.Revision;//.NET解释引擎版本
                Label5.Text = "服务器操作系统版本：" + Environment.OSVersion.ToString();//服务器操作系统版本
                Label6.Text = "服务器IIS版本：" + Request.ServerVariables["SERVER_SOFTWARE"];//服务器IIS版本
                Label7.Text = "HTTP访问端口：" + Request.ServerVariables["SERVER_PORT"];//HTTP访问端口
                Label8.Text = "虚拟目录的绝对路径：" + Request.ServerVariables["APPL_RHYSICAL_PATH"];//虚拟目录的绝对路径
                Label9.Text = "执行文件的绝对路径：" + Request.ServerVariables["PATH_TRANSLATED"];//执行文件的绝对路径
                Label10.Text = "虚拟目录Session总数：" + Session.Contents.Count.ToString();//虚拟目录Session总数
                Label11.Text = "虚拟目录Application总数：" + Application.Contents.Count.ToString();//虚拟目录Application总数
                Label12.Text = "域名主机：" + Request.ServerVariables["HTTP_HOST"];//域名主机
                Label13.Text = "服务器区域语言：" + Request.ServerVariables["HTTP_ACCEPT_LANGUAGE"];//服务器区域语言
                Label14.Text = "用户信息：" + Request.ServerVariables["HTTP_USER_AGENT"];
                Label14.Text="CPU个数："+Environment.GetEnvironmentVariable("NUMBER_OF_PROCESSORS");//CPU个数
                Label15.Text = "CPU类型：" + Environment.GetEnvironmentVariable("PROCESSOR_IDENTIFIER");//CPU类型
                Label16.Text = "进程开始时间：" + GetPrStart();//进程开始时间
                Label17.Text = "AspNet 内存占用：" + GetAspNetN();//AspNet 内存占用
                Label18.Text = "AspNet CPU时间：" + GetAspNetCpu();//AspNet CPU时间
                Label19.Text = "FSO 文本文件读写：" + Check("Scripting.FileSystemObject");//FSO 文本文件读写
                Label20.Text = "应用程序占用内存" + GetServerAppN();//应用程序占用内存
            }

ASP.NET获取客户端信息

客户端IP：Page.Request.UserHostAddress
用户信息：Page.User;
服务器电脑名称：Page.Server.MachineName
当前用户电脑名称： System.Net.Dns.GetHostName()
当前电脑名： System.Environment.MachineName
当前电脑所属网域： System.Environment.UserDomainName
当前电脑用户： System.Environment.UserName

浏览器类型：Request.Browser.Browser
浏览器标识：Request.Browser.Id
浏览器版本号：Request.Browser.Version
浏览器是不是测试版本：Request.Browser.Beta
浏览器的分辨率(像素)：Request["width"].ToString() + "*" + Request["height"].ToString();//1280/1024

客户端的操作系统：Request.Browser.Platform
是不是win16系统：Request.Browser.Win16
是不是win32系统：Request.Browser.Win32


//透过代理取IP
string GetIp()
{
//可以透过代理服务器
string userIP = Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
if (userIP == null || userIP == "")
{
//没有代理服务器,如果有代理服务器获取的是代理服务器的IP
userIP = Request.ServerVariables["REMOTE_ADDR"];
}
return userIP;
}

 C#实现页面加载

protected void Page_Load(object sender, EventArgs e)
    {
        Loading();
    }


public void Loading()
    {
        HttpContext hc = HttpContext.Current;
        //创建一个页面居中的div
        hc.Response.Write("<div id='loading'style='position: absolute; height: 100px; text-align: center;z-index: 9999; left: 50%; top: 50%; margin-top: -50px; margin-left: -175px;'> ");
        hc.Response.Write("<br />页面正在加载中，请稍候<br /><br /> ");
        hc.Response.Write("<table border='0' cellpadding='0' cellspacing='0' style='background-image: url(images/Progress/plan-bg.gif);text-align: center;  300px;'> ");
        hc.Response.Write("<tr><td style='height: 20px; text-align: center'><marquee direction='right' scrollamount='30' width='290px'> <img height='10' src='images/Progress/plan-wait.gif' width='270' />");
        hc.Response.Write("</marquee></td></tr></table></div>");
        //hc.Response.Write("<script>mydiv.innerText = '';</script>");
        hc.Response.Write("<script type=text/javascript>");
        //最重要是这句了,重写文档的onreadystatechange事件,判断文档是否加载完毕
        hc.Response.Write("function document.onreadystatechange()");
        hc.Response.Write(@"{ try  
                                   {
                                    if (document.readyState == 'complete') 
                                    {
                                         delNode('loading');
                                        
                                    }
                                   }
                                 catch(e)
                                    {
                                        alert('页面加载失败');
                                    }
                                                        } 

                            function delNode(nodeId)
                            {   
                                try
                                {   
                                      var div =document.getElementById(nodeId); 
                                      if(div !==null)
                                      {
                                          div.parentNode.removeChild(div);   
                                          div=null;    
                                          CollectGarbage(); 
                                      } 
                                }
                                catch(e)
                                {   
                                   alert('删除ID为'+nodeId+'的节点出现异常');
                                }   
                            }

                            ");

        hc.Response.Write("</script>");
        hc.Response.Flush();
    }

 Http请求图片显示：

public Image byteArrayToImage()    
{        
WebRequest myWebRequest = WebRequest.Create("图片地址");        
using (WebResponse myWebResponse = myWebRequest.GetResponse())        
{            using (Stream ReceiveStream = myWebResponse.GetResponseStream())            {                byte[] byteArrayIn = new byte[ReceiveStream.Length];                
using (MemoryStream ms = new MemoryStream(byteArrayIn))                
{       
Image.FromStream(ms);                
}            
}        
}
}

通过文件流判断文件编码:

public static System.Text.Encoding GetFileEncode(Stream stream)
        {
            BinaryReader br = new BinaryReader(stream, Encoding.Default);
            byte[] bb = br.ReadBytes(3);
            br.Close();

            //通过头的前三位判断文件的编码
            if (bb[0] >= 0xFF)
            {
                if (bb[0] == 0xEF && bb[1] == 0xBB && bb[2] == 0xBF)
                {
                    return Encoding.UTF8;
                }
                else if (bb[0] == 0xFE && bb[1] == 0xFF)
                {
                    return Encoding.BigEndianUnicode;
                }
                else if (bb[0] == 0xFF && bb[1] == 0xFE)
                {
                    return Encoding.Unicode;
                }
                else
                {
                    return Encoding.Default;
                }
            }
            else
            {
                return Encoding.Default;
            }
        }