【下载文档:  asp.net ajax实现无刷新验证码.txt 】

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asp.net ajax实现无刷新验证码
1、首先是在后台验证码的aspx文件的Page_Load中的事件代码： 复制代码 代码如下: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Drawing; namespace 学生在线考试系统 { public partial class AjaxAutoCode : System.Web.UI.Page { //验证数字 public string authcode = string.Empty; protected void Page_Load(object sender, EventArgs e) { #region 第一种产生验证码的方法 Random random = new Random(); authcode = random.Next(1111, 9999).ToString(); //构造图片 Bitmap image = new Bitmap(authcode.Length * 12, 25); //创建画布 Graphics g = Graphics.FromImage(image); try { g.Clear(Color.White); 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); //链接两点的线条 g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2); } Font font = new Font("Arial", 12, FontStyle.Bold | FontStyle.Italic); System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush( new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkBlue, 1.2f, true); g.DrawString(authcode, font, brush, 2, 2); //画图片的前景噪点 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())); } 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); ms.WriteTo(this.Response.OutputStream); ms.Close(); this.Response.ContentType = "image/gif"; } finally { image.Dispose(); g.Dispose(); } #endregion } } } 2、其次在显示验证码的页面定义一个JS函数 复制代码 代码如下: function fGetCode() { document.getElementById("getcode").src="Default2.aspx?"+Math.random(); } 3.再编辑前台页面aspx,下面是前台页面的代码片段 复制代码 代码如下: 验证码 更换验证码