1. 設置兩個窗體。
一． 第一個窗體是製作驗證碼的。
驗證碼爲4位數，不區分大小寫
代碼如下：
在窗體中添加一個圖片框
<asp:Image ID="Image1" src="image.aspx" runat="server" />
protected void Page_Load(object sender, EventArgs e)
{
this.CreateCheckCodeImage(GenerateCheckCode());
}
private string GenerateCheckCode()
{
int number;
char code;
string checkCode = String.Empty;
System.Random random = new Random();
for (int i = 0; i < 5; i++)
{
number = random.Next();
if (number % 2 == 0)
code = (char)('0' + (char)(number % 10));
else
code = (char)('A' + (char)(number % 26));
checkCode += code.ToString();
}
Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));
return checkCode;
}
private void CreateCheckCodeImage(string checkCode)
{
if (checkCode == null || checkCode.Trim() == String.Empty)
return;
System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
Graphics g = Graphics.FromImage(image);
try
{
//生¦¨²成¨¦隨?機¨²生¦¨²成¨¦器¡Â
Random random = new Random();
//清?空?圖ª?片?背À3景¡ã色¦?
g.Clear(Color.White);
//畫-圖ª?片?的Ì?背À3景¡ã噪?音°?線?
for (int i = 0; i < 25; 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);
}
Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
g.DrawString(checkCode, font, brush, 2, 2);
//畫-圖ª?片?的Ì?前¡ã景¡ã噪?音°?點Ì?
for (int i = 0; i < 100; i++)
{
int x = random.Next(image.Width);
int y = random.Next(image.Height);
image.SetPixel(x, y, Color.FromArgb(random.Next()));
}
//畫-圖ª?片?的Ì?邊À?框¨°線?
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.ContentType = "image/Gif";
Response.BinaryWrite(ms.ToArray());
}
finally
{
g.Dispose();
image.Dispose();
}
}
二． 第二個窗體是顯示圖片和驗證用戶輸入的值
代碼如下：
按鈕事件：
protected void Button2_Click(object sender, EventArgs e)
{
if (Request.Cookies["CheckCode"] == null)
{
lblMessage.Text = "您的瀏覽器設置已被禁用 Cookies，您必須設置瀏覽器允許使用Cookies 選項後才能完成測試";
lblMessage.Visible = true;
return;
}
if (String.Compare(Request.Cookies["CheckCode"].Value, txtCheckCode.Text, true) != 0)
{
lblMessage.Text = "驗證碼錯誤請輸入正確的驗證碼";
lblMessage.Visible = true;
return;
}
if (String.Compare(Request.Cookies["CheckCode"].Value, txtCheckCode.Text, true) == 0)
{
lblMessage.Text = "恭喜您驗證碼輸入正確";
lblMessage.Visible = true;
return;
}
}
看不清楚下一張：
function ClikImage() {
var x = document.getElementById("Image1");
x.setAttribute('src', 'image.aspx?' + Math.random());
}
<a ID="HyperLink1" href="javascript:ClikImage()" runat="server">看不清下一站</a>