Asp.net(C#)实现验证码功能

Asp.net(C#)实现验证码功能

新建一个专门用来创建验证码图片的页面ValidateCode.aspx 它的后台cs文件代码如下： PageLoad private   void  Page_Load( object  sender, System.EventArgs e)          {             string checkCode = CreateRandomCode(4);             Session["CheckCode"] = checkCode;             CreateImage(checkCode);         } 其中CreateRandomCode是自定义的函数，参数代表验证码位数 private   string  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" ;             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(35);                 if(temp == t)                 {                     return CreateRandomCode(codeCount);                 }                 temp = t;                 randomCode += allCharArray[t];             }             return randomCode;         } CreateImage也是一个自定义的函数，用于生成图 private   void  CreateImage( string  checkCode)          {             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.White);             //g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height);             g.Clear(Color.Blue);             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.Width,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();         } //g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height); g.Clear(Color.Blue); 这两种方法都可以改变生成图片的背景颜色 下面那个for循环用来生成一些随机的水平线 在需要用到验证码的页面添加一个<asp:Image>控件即可，但是要把ImageUrl指向生成验证码的页面 < asp:Image Runat = " server "  ID = " ImageCheck "  ImageUrl="ValidateCode.aspx" ></ asp:Image > private string 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" ; 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(35); if(temp == t) { return CreateRandomCode(codeCount); } temp = t; randomCode += allCharArray[t]; } return randomCode; }