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c#生成验证码 点击可刷新

技术2022-05-11  1

先建一张生成验证码的网页CheckCode.aspx: CheckCode.aspx.cs代码如下 添加引用: using System.IO; using System.Drawing; using System.Drawing.Imaging; using System.Drawing.Drawing2D; public partial class Default2 : System.Web.UI.Page { private Bitmap validateimage; private Graphics g; protected void Page_Load(object sender, EventArgs e) { Response.BufferOutput = true; //特别注意 Response.Cache.SetExpires(DateTime.Now.AddMilliseconds(-1));//特别注意 Response.Cache.SetCacheability(HttpCacheability.NoCache);//特别注意 Response.AppendHeader(" Pragma", "No-Cache"); //特别注意 string VNum = MakeValidateCode(); Session["VNum"] = VNum;//取得验证码,以便后来验证 ValidateCode(VNum); } public void ValidateCode(string VNum) { validateimage = new Bitmap(60, 20, PixelFormat.Format24bppRgb); g = Graphics.FromImage(validateimage); g.FillRectangle(new LinearGradientBrush(new Point(0, 0), new Point(110, 20), Color.FromArgb(240, 255, 255, 255), Color.FromArgb(240, 255, 255, 255)), 0, 0, 200, 200); //矩形框 g.DrawString(VNum, new Font("arial", 11), new SolidBrush(Color.Red), new PointF(6, 0));//字体/颜色 g.Save(); MemoryStream ms = new MemoryStream(); validateimage.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); Response.ClearContent(); Response.C; Response.BinaryWrite(ms.ToArray()); Response.End(); } string MakeValidateCode() { char[] s = new char[] { '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', 'v', 'w', 'x', 'y', 'z','A','B', 'C','D','E','F','G','H','I','J','K','L','M','N','P','Q','I','S','T','U','V', 'W','X','Y','Z'};//枚举数组 string num = ""; Random r = new Random(); for (int i = 0; i < 5; i++) { num += s[r.Next(0, s.Length)].ToString(); } return num; } } 然后是显示验证码的页面 的html中加入<img src="Default2.aspx" id="yzm" alt="点击刷新" /> 在</head>之前一行加入javascript脚本语言如下(当然写在JS文件里面更好): <script type="text/javascript"> function reloadcode(){ document.getElementById("yzm").src ="CheckCode.aspx"; } </script>

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