创建一个专门用于创建验证码图片的页面ValidateCode.aspx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); }
CreaterandomCode是自定义函数,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、9A,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也是生成图片的自定义函数
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。下面的for循环用于生成一些需要使用验证码的页面的随机水平线<asp:Image>控制器可以,但Imageurl应该指向生成验证码的页面
< asp:Image Runat = " server " ID = " ImageCheck " ImageUrl="ValidateCode.aspx" ></ asp:Image >
![](/images/780-200-2.jpg)