.net实现验证码功能(转)

　

转自：http://www.cnblogs.com/dreamof/archive/2009/01/22/1379822.html

一、验证码简介 　　验证码功能一般是用于防止批量注册的，不少网站为了防止用户利用机器人自动注册、登录、灌水，都采用了验证码技术。所谓验证码，就是将一串随机产生的数字或字母或符号或文字，生成一幅图片， 图片里加上一些干扰象素（防止OCR），由用户肉眼识别其中的验证码信息，输入表单提交网站验证，验证成功后才能使用某项功能。
　　常见的验证码有如下几种： 　　1、纯数字验证码，一般为四位随机数字； 　　2、数字+字母验证码，一般从数字（0~9）和字母(A~Z和a~z)中随机抽出几个字符组成； 　　3、汉字验证码，相对而言，这种验证码比较少见一点，实现起来也相对复杂一些，但在不少网站中还是可以看到的；

　　二、验证码的实现 　　1、纯数字验证码的实现 　　纯数字验证码的实现相对比较简单，可通过以下两种方法来实现 　　（1）使用随机数方式，代码如下：　

        private String GetRandomint(int codeCount)         {             Random random =new Random();             string min ="";             string max ="";             for (int i =0; i < codeCount; i++)             {                 min +="1";                 max+="9";             }                 return (random.Next(Convert.ToInt32(min),Convert.ToInt32(max)).ToString());         }

　　(2)使用随机组合方式，代码如下：

        privatestring CreateRandomCode(int codeCount)         {             string allChar ="0,1,2,3,4,5,6,7,8,9";             string[] allCharArray = allChar.Split(',');             string randomCode ="";             int temp =-1;             Random rand =new Random();             for (int i =0; i < codeCount; i++)             {                 if (temp !=-1)                 {                     rand =new Random(i * temp * ((int)DateTime.Now.Ticks));                 }                 int t = rand.Next(9);                 if (temp == t)                 {                     return CreateRandomCode(codeCount);                 }                 temp = t;                 randomCode += allCharArray[t];             }             return randomCode;         }

　　2、数字+字母验证码的实现，代码如下：

        privatestring CreateRandomCode(int codeCount)         {             string allChar ="0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z";             string[] allCharArray = allChar.Split(',');             string randomCode ="";             int temp =-1;             Random rand =new Random();             for (int i =0; i < codeCount; i++)             {                 if (temp !=-1)                 {                     rand =new Random(i * temp * ((int)DateTime.Now.Ticks));                 }                 int t = rand.Next(61);                 if (temp == t)                 {                     return CreateRandomCode(codeCount);                 }                 temp = t;                 randomCode += allCharArray[t];             }             return randomCode;         }

　　3、汉字验证码的实现，代码如下：

        /**/         /*     此函数在汉字编码范围内随机创建含两个元素的十六进制字节数组，每个字节数组代表一个汉字，并将     四个字节数组存储在object数组中。     参数：strlength，代表需要产生的汉字个数     */         publicstaticobject[] CreateRegionCode(int strlength)         {             //定义一个字符串数组储存汉字编码的组成元素             string[] rBase =new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };             Random rnd =new Random();             //定义一个object数组用来             object[] bytes =newobject[strlength];
            /**/             /*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中          每个汉字有四个区位码组成          区位码第1位和区位码第2位作为字节数组第一个元素          区位码第3位和区位码第4位作为字节数组第二个元素         */             for (int i =0; i < strlength; i++)             {                 //区位码第1位                 int r1 = rnd.Next(11, 14);                 string str_r1 = rBase[r1].Trim();
                //区位码第2位                 rnd =new Random(r1 *unchecked((int)DateTime.Now.Ticks) + i);//更换随机数发生器的种子避免产生重复值                 int r2;                 if (r1 ==13)                 {                     r2 = rnd.Next(0, 7);                 }                 else                 {                     r2 = rnd.Next(0, 16);                 }                 string str_r2 = rBase[r2].Trim();
                //区位码第3位                 rnd =new Random(r2 *unchecked((int)DateTime.Now.Ticks) + i);                 int r3 = rnd.Next(10, 16);                 string str_r3 = rBase[r3].Trim();
                //区位码第4位                 rnd =new Random(r3 *unchecked((int)DateTime.Now.Ticks) + i);                 int r4;                 if (r3 ==10)                 {                     r4 = rnd.Next(1, 16);                 }                 elseif (r3 ==15)                 {                     r4 = rnd.Next(0, 15);                 }                 else                 {                     r4 = rnd.Next(0, 16);                 }                 string str_r4 = rBase[r4].Trim();
                //定义两个字节变量存储产生的随机汉字区位码                 byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);                 byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);                 //将两个字节变量存储在字节数组中                 byte[] str_r =newbyte[] { byte1, byte2 };
                //将产生的一个汉字的字节数组放入object数组中                 bytes.SetValue(str_r, i);             }             return bytes;         }

　　三、具体实例　 　　(实例1)　

<body>     <form id="form1" runat="server">     <div>        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>         <asp:Image ID="Image1" runat="server" ImageUrl="png.aspx"/><br />         <br />        <asp:Button ID="Button2" runat="server" OnClick="Button2_Click" Text="Button"/>         <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">             <asp:ListItem Value="3">默认</asp:ListItem>             <asp:ListItem Value="1">文字</asp:ListItem>             <asp:ListItem Value="2">数字</asp:ListItem>             <asp:ListItem Value="3">混合</asp:ListItem>         </asp:DropDownList></div>     </form></body>

        protectedvoid DropDownList1_SelectedIndexChanged(object sender, EventArgs e)         {             switch (DropDownList1.SelectedValue)             {                 case"1":                     Image1.ImageUrl ="png.aspx?aa=1";                     break;                 case"2":                     Image1.ImageUrl ="png.aspx?aa=2";                     break;                 case"3":                     Image1.ImageUrl ="png.aspx?aa=3";                     break;             }         }         protectedvoid Button2_Click(object sender, EventArgs e)         {             if (TextBox1.Text == Session["gif"].ToString())                 Response.Write("OK,正确");             else                 Response.Write("验证码不符合");         }

    publicpartialclass png : System.Web.UI.Page     {                 protectedvoid Page_Load(object sender, EventArgs e)         {             switch (Request.QueryString["aa"])             {                 case"1":                     gif = stxt(10);                     Session["gif"] = stxt(10);                     break;                 case"2":                     gif = GetRandomint(4);                     Session["gif"] = GetRandomint(4);                     break;                 case"3":                     gif = CreateRandomCode(4);                     Session["gif"] = CreateRandomCode(4);                     break;                 default:                     gif = CreateRandomCode(4);                     Session["gif"] = CreateRandomCode(4);                     break;             }             CreateImage(Session["gif"].ToString());         }
        private String GetRandomint(int codeCount)         {             Random random =new Random();             string min ="";             string max ="";             for (int i =0; i < codeCount; i++)             {                 min +="1";                 max+="9";             }                 return (random.Next(Convert.ToInt32(min),Convert.ToInt32(max)).ToString());         }         /**/         /*     此函数在汉字编码范围内随机创建含两个元素的十六进制字节数组，每个字节数组代表一个汉字，并将     四个字节数组存储在object数组中。     参数：strlength，代表需要产生的汉字个数     */         publicstaticobject[] CreateRegionCode(int strlength)         {             //定义一个字符串数组储存汉字编码的组成元素             string[] rBase =new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };             Random rnd =new Random();             //定义一个object数组用来             object[] bytes =newobject[strlength];
            /**/             /*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中          每个汉字有四个区位码组成          区位码第1位和区位码第2位作为字节数组第一个元素          区位码第3位和区位码第4位作为字节数组第二个元素         */             for (int i =0; i < strlength; i++)             {                 //区位码第1位                 int r1 = rnd.Next(11, 14);                 string str_r1 = rBase[r1].Trim();
                //区位码第2位                 rnd =new Random(r1 *unchecked((int)DateTime.Now.Ticks) + i);//更换随机数发生器的种子避免产生重复值                 int r2;                 if (r1 ==13)                 {                     r2 = rnd.Next(0, 7);                 }                 else                 {                     r2 = rnd.Next(0, 16);                 }                 string str_r2 = rBase[r2].Trim();
                //区位码第3位                 rnd =new Random(r2 *unchecked((int)DateTime.Now.Ticks) + i);                 int r3 = rnd.Next(10, 16);                 string str_r3 = rBase[r3].Trim();
                //区位码第4位                 rnd =new Random(r3 *unchecked((int)DateTime.Now.Ticks) + i);                 int r4;                 if (r3 ==10)                 {                     r4 = rnd.Next(1, 16);                 }                 elseif (r3 ==15)                 {                     r4 = rnd.Next(0, 15);                 }                 else                 {                     r4 = rnd.Next(0, 16);                 }                 string str_r4 = rBase[r4].Trim();
                //定义两个字节变量存储产生的随机汉字区位码                 byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);                 byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);                 //将两个字节变量存储在字节数组中                 byte[] str_r =newbyte[] { byte1, byte2 };
                //将产生的一个汉字的字节数组放入object数组中                 bytes.SetValue(str_r, i);             }             return bytes;         }         privatestring stxt(int num)         {             Encoding gb = Encoding.GetEncoding("gb2312");
            //调用函数产生10个随机中文汉字编码             object[] bytes = CreateRegionCode(num);             string strtxt ="";
            //根据汉字编码的字节数组解码出中文汉字             for (int i =0; i < num; i++)             {                 strtxt += gb.GetString((byte[])Convert.ChangeType(bytes[i], typeof(byte[])));             }             return strtxt;         }         ///<summary>         /// 这个是使用字母,数字混合         ///</summary>         ///<param name="VcodeNum"></param>         ///<returns></returns>        privatestring CreateRandomCode(int codeCount)         {             string allChar ="0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z";             string[] allCharArray = allChar.Split(',');             string randomCode ="";             int temp =-1;             Random rand =new Random();             for (int i =0; i < codeCount; i++)             {                 if (temp !=-1)                 {                     rand =new Random(i * temp * ((int)DateTime.Now.Ticks));                 }                 int t = rand.Next(61);                 if (temp == t)                 {                     return CreateRandomCode(codeCount);                 }                 temp = t;                 randomCode += allCharArray[t];             }             return randomCode;         }
        privatevoid CreateImage(string checkCode)         {             int iwidth = (int)(checkCode.Length *20);             System.Drawing.Bitmap image =new System.Drawing.Bitmap(iwidth, 25);             Graphics g = Graphics.FromImage(image);             Font f =new System.Drawing.Font("Arial", 10, System.Drawing.FontStyle.Bold);             Brush b =new System.Drawing.SolidBrush(Color.White);             //g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height);                g.Clear(Color.Black);             g.DrawString(checkCode, f, b, 3, 3);             Pen blackPen =new Pen(Color.Black, 0);             Random rand =new Random();             //for (int i=0;i<5;i++)                //{                    //    int y = rand.Next(image.Height);              //    g.DrawLine(blackPen,0,y,image.W

idth,y);             //}                    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();         }     }

　　(实例2):20101018续加

        <script language="Javascript">         function Regist()         {             var url ="";             url ="/GZPI/Service/Registry/ViewProtocol.aspx";             window.open(url);                returnfalse;         }         function LoginClick()         {             if(document.Login.UserName.value =="")             {                 alert("用户名不能为空！");                 returnfalse;             }             document.Login.submit();             document.Login.Password.value ="";             returnfalse;         }                 function f_refreshtype()         {                var Image1 = document.getElementById("IMGCheckCode");               if (Image1 !=null)                {                    Image1.src = Image1.src +"?";              }         }                </script>                         <TABLE cellSpacing="0" cellPadding="5" width="100%" border="0">                             <TR>                                 <TD class="fontblack" align="right" width="30%">用 户 名：</TD>                                 <TD vAlign="bottom" align="left" width="62%"><input id="Text1" style="BORDER-RIGHT: #43a7e2 1px solid; BORDER-TOP: #43a7e2 1px solid; BACKGROUND: #fcfcfc; BORDER-LEFT: #43a7e2 1px solid; BORDER-BOTTOM: #43a7e2 1px solid"                                         size="13" name="UserName" width="100px">                                 </TD>                             </TR>                             <TR>                                 <TD class="fontblack" align="right" height="23">密 &nbsp;&nbsp;&nbsp;码：</TD>                                 <TD vAlign="bottom" align="left" height="23"><input id="Password1" style="BORDER-RIGHT: #43a7e2 1px solid; BORDER-TOP: #43a7e2 1px solid; BACKGROUND: #fcfcfc; BORDER-LEFT: #43a7e2 1px solid; BORDER-BOTTOM: #43a7e2 1px solid"                                         type="password" size="13" name="Password" width="100px">                                 </TD>                             </TR>                             <TR>                                 <TD class="fontblack" align="right" height="23">校&nbsp;验 码：</TD>                                 <TD valign="top" align="left" height="23"><FONT face="宋体"><INPUT id="CheckCode" style="BORDER-RIGHT: #43a7e2 1px solid; BORDER-TOP: #43a7e2 1px solid; BACKGROUND: #fcfcfc; BORDER-LEFT: #43a7e2 1px solid; BORDER-BOTTOM: #43a7e2 1px solid"                                             width="100px" size="13" name="CheckCode">&nbsp;</FONT><a style="CURSOR: hand" onclick="f_refreshtype()" title="看不清楚?点击获取新的校验码!" border="0"><IMG id="IMGCheckCode" src="../GenerateCheckCode.aspx"></a>                                 </TD>                             </TR>                             <TR vAlign="bottom" align="center">                                 <TD class="dlbuttom" colSpan="2" height="23"><input id="Image1" style="CURSOR: hand" onclick="return LoginClick();" tabIndex="3" type="image"                                         height="17" width="55" src="images/login.gif" border="0" name="OkButton">&nbsp;&nbsp;&nbsp;                                     <input type="image" onClick="return Regist();" border='0' src='images/zuce.gif' width='55'                                         height='17' ID="Image2" NAME="Image2">                                 </TD>                             </TR>                         </TABLE>

    private void OK_Click(object sender, System.EventArgs e)         {             if (!CheckCodeSame(CheckCode.Text.Trim()))             {                                     System.Web.HttpContext.Current.Response.Write("<Script Language='JavaScript'>window.alert('校验码错误！请重新输入！');window.close();</script>");                 return;             }                     int userType = 1;             try             {                 userType = int.Parse(UserType.Text);             }             catch             {             }
            GatewayManager gateway = new GatewayManager(corpCode.Text,collegeCode.Text,chargeCode.Text,userName.Text,password.Text,userType);             gateway.Login(this);         }
        /// <summary>         /// 判断输入的校验码是否正确         /// </summary>         /// <param name="checkCode"></param>         /// <returns></returns>         public static bool CheckCodeSame(string checkCode)         {             bool bSame = false; ;
            if (HttpContext.Current.Session["CheckCode"] != null)             {                 if (checkCode.ToUpper() == HttpContext.Current.Session["CheckCode"].ToString().ToUpper())                 {                     bSame = true;                 }             }             return bSame;         }

　　

<HTML>     <HEAD>         <title>GenerateCheckCode</title>         <meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">         <meta name="CODE_LANGUAGE" Content="C#">         <meta name="vs_defaultClientScript" content="JavaScript">         <meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">     </HEAD>     <body>         <form id="form1" runat="server">             <div><FONT face="宋体"></FONT>             </div>         </form>     </body></HTML>

using System; using System.Collections; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Drawing; using System.Drawing.Drawing2D;
 namespace GZPI.Gateway {     ///<summary>     /// GenerateCheckCode 的摘要说明。     ///</summary>    publicclass GenerateCheckCode : System.Web.UI.Page     {         privatevoid Page_Load(object sender, System.EventArgs e)         {             // 在此处放置用户代码以初始化页面            this.CreateCheckCodeImage(GenerateCheckCodes(4));         }
        #region Web 窗体设计器生成的代码         overrideprotectedvoid OnInit(EventArgs e)         {             //             // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。             //             InitializeComponent();             base.OnInit(e);         }                  ///<summary>         /// 设计器支持所需的方法 - 不要使用代码编辑器修改         /// 此方法的内容。         ///</summary>        privatevoid InitializeComponent()         {                 this.Load +=new System.EventHandler(this.Page_Load);         }         #endregion
        privatestring GenerateCheckCodes(int iCount)         {             int number;             string checkCode = String.Empty;             int iSeed = DateTime.Now.Millisecond;             System.Random random =new Random(iSeed);             for (int i =0; i < iCount; i++)             {                 number = random.Next(10);                 checkCode += number.ToString();             }
            Session["CheckCode"] = checkCode;             return checkCode;         }

        privatevoid CreateCheckCodeImage(string checkCode)         {             if (checkCode ==null|| checkCode.Trim() == String.Empty)                 return;             int iWordWidth =15;             int iImageWidth = checkCode.Length * iWordWidth;             Bitmap image =new Bitmap(iImageWidth, 20);             Graphics g = Graphics.FromImage(image);             try             {                 //生成随机生成器                 Random random =new Random();                 //清空图片背景色                 g.Clear(Color.White);
                //画图片的背景噪音点                for (int i =0; i <20; i++)                 {                     int x1 = random.Next(image.Width);                     int x2 = random.Next(image.Width);                     int y1 = random.Next(image.Height);                     int y2 = random.Next(image.Height);                     g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);                 }
                //画图片的背景噪音线                 for (int i =0; i <2; i++)                 {                     int x1 =0;                     int x2 = image.Width;                     int y1 = random.Next(image.Height);                     int y2 = random.Next(image.Height);                     if (i ==0)                     {                         g.DrawLine(new Pen(Color.Gray, 2), x1, y1, x2, y2);                     }                              }
                 for (int i =0; i < checkCode.Length; i++)                 {
                    string Code = checkCode[i].ToString();                     int xLeft = iWordWidth * (i);                     random =new Random(xLeft);                     int iSeed = DateTime.Now.Millisecond;                     int iValue = random.Next(iSeed) %4;                     if (iValue ==0)                     {                         Font font =new Font("Arial", 13, (FontStyle.Bold | System.Drawing.FontStyle.Italic));                         Rectangle rc =new Rectangle(xLeft, 0, iWordWidth, image.Height);                         LinearGradientBrush brush =new LinearGradientBrush(rc, Color.Blue, Color.Red, 1.5f, true);                         g.DrawString(Code, font, brush, xLeft, 2);                     }                     elseif (iValue ==1)                     {                         Font font =new System.Drawing.Font("楷体", 13, (FontStyle.Bold));                         Rectangle rc =new Rectangle(xLeft, 0, iWordWidth, image.Height);                         LinearGradientBrush brush =new LinearGradientBrush(rc, Color.Blue, Color.DarkRed, 1.3f, true);                         g.DrawString(Code, font, brush, xLeft, 2);                     }                     elseif (iValue ==2)                     {                         Font font =new System.Drawing.Font("宋体", 13, (System.Drawing.FontStyle.Bold));                         Rectangle rc =new Rectangle(xLeft, 0, iWordWidth, image.Height);                         LinearGradientBrush brush =new LinearGradientBrush(rc, Color.Green, Color.Blue, 1.2f, true);                         g.DrawString(Code, font, brush, xLeft, 2);                     }                     elseif (iValue ==3)                     {                         Font font =new System.Drawing.Font("黑体", 13, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Bold));                         Rectangle rc =new Rectangle(xLeft, 0, iWordWidth, image.Height);                         LinearGradientBrush brush =new LinearGradientBrush(rc, Color.Blue, Color.Green, 1.8f, true);                         g.DrawString(Code, font, brush, xLeft, 2);                     }                 }                 //////画图片的前景噪音点                 //for (int i = 0; i < 8; i++)                 //{                 //    int x = random.Next(image.Width);                 //    int y = random.Next(image.Height);                 //    image.SetPixel(x, y, Color.FromArgb(random.Next()));                 //}                 //画图片的边框线                 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width -1, image.Height -1);                 System.IO.MemoryStream ms =new System.IO.MemoryStream();                 image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);                 Response.ClearContent();
                Response.BinaryWrite(ms.ToArray());             }             finally             {                 g.Dispose();                 image.Dispose();             }         }     } } 

　　四、效果图展示 　　验证码数字 　　验证码数字+字母 　　验证码汉字