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>
