asp.net验证码图片生成示例
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asp.net验证码图片生成示例
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? ? 驗證碼，一個很常見的東西。不管你是使用者還是開發者，這個東西80%的人都見到過，但是之前有人給我說過這么一句話“內行看門道，外行看熱鬧！”，仔細琢磨一下還真的是那么一回事。對于怎么實現驗證碼，閑話不多扯，直接上代碼。
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我們需要在前臺代碼中寫一段<img>，src指向一張頁面（ValidateImage.aspx）
<html>
<head>
<title>數字驗證碼</title> <script language="javascript">function changeImg() {$("#imgCheckNo").attr("src", "ValidateImage.aspx?r=" + getRandom(999));}function getRandom(n) { return Math.floor(Math.random() * n + 1) } </script>
</head> <body>
<div> <img id="imgCheckNo" src="ValidateImage.aspx" style="border-color: #000000; border-width: 1px;border-style: Solid"><span οnclick="changeImg();">看不清?換一張</span></div> <div><div class="labelCss">驗證碼：</div> <div> <asp:TextBox ID="tbxCheckNo" runat="server" CssClass="tbxCss"></asp:TextBox> </div> <div> <asp:Button ID="btnSubmit" runat="server" Text="立即注冊" OnClick="btnSubmit_Click" /> </div>
?</body>
</html>//ValidateImage.aspx 用來生產驗證碼圖片，并將驗證碼的碼值保存到cookie中。public partial class ValidateImage : System.Web.UI.Page{protected void Page_Load(object sender, EventArgs e){this.CreateCheckCodeImage(RndNum());}/// <summary>生成驗證碼/// </summary>/// <returns></returns>private string RndNum(){int number;char code;string checkCode = String.Empty;System.Random random = new Random();for (int i = 0; i < 4; i++){number = random.Next();if (number % 2 == 0)code = (char)('0' + (char)(number % 10));elsecode = (char)('A' + (char)(number % 26));checkCode += code.ToString();}Response.Cookies.Add(new HttpCookie("yzmcode", checkCode));return checkCode;}/// <summary>向頁面生成驗證碼Gif圖片/// </summary>/// <param name="checkCode"></param>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{//生成隨機生成器Random random = new Random();//清空圖片背景色 g.Clear(Color.White);//畫圖片的背景噪音線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);//畫圖片的前景噪音點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()));}//畫圖片的邊框線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();}}}//最后就是后臺事件，判斷當前驗證碼是否正確。#region 頁面控件事件protected void btnSubmit_Click(object sender, EventArgs e){if (String.Compare(Request.Cookies["yzmcode"].Value, tbxCheckNo.Text, true) != 0){Response.Write("<script>alert('驗證碼錯誤!')</script>");}else{// Response.Write("<script>alert('驗證嗎正確!!!')</script>"); }}#endregion
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轉載于:https://www.cnblogs.com/felix-wang/p/6943349.html
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