Asp.net(C#)實現驗證碼功能代碼

建立一個專門用來建立驗證碼圖片的頁面ValidateCode.aspx
它的後台cs檔案代碼如下：
PageLoad 複製代碼 代碼如下:private void Page_Load(object sender, System.EventArgs e)
{
string checkCode = CreateRandomCode(4);
Session["CheckCode"] = checkCode;
CreateImage(checkCode);
}

其中CreateRandomCode是自訂的函數，參數代表驗證碼位元 複製代碼 代碼如下: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也是一個自訂的函數，用於產生圖 複製代碼 代碼如下: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);

這兩種方法都可以改變產生圖片的背景顏色。下面那個for迴圈用來產生一些隨機的水平線
在需要用到驗證碼的頁面添加一個<asp:Image>控制項即可，但是要把ImageUrl指向產生驗證碼的頁面 複製代碼 代碼如下:<asp:Image Runat="server" ID="ImageCheck" ImageUrl="ValidateCode.aspx"></asp:Image>