现在大部分网站登陆时都会要求输入验证码,在网上也看了一些范例,现在总结一下如何实现无刷新页面生成验证码。
效果图:
实现方式:
前台:
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< div > < span >Identifying Code:</ span > < asp:TextBox ID = "txtValidationCode" runat = "server" Width = "130px" MaxLength = "4" ></ asp:TextBox > < img id = "imgYZ" class = "code" style = " height:23px; width:65px;" < img src = "../images/btn_change.gif" title = "Change" class = "btn_change" Style = "cursor: hand" onclick = "ImgChange()" /> </ div > |
JS:
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<script language= "javascript" type= "text/javascript" > function ImgChange() { var img=document.getElementById( "imgYZ" ); img.click(); } </script> |
ashx:
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using System; using System.Web; using CLAIMS.BLL; using System.Data; using System.Configuration; using System.Web.SessionState; using System.Drawing; public class Img : IHttpHandler, IRequiresSessionState { public void ProcessRequest (HttpContext context) { context.Response.ContentType = "image/Jpeg" ; string s_random = "" ; System.IO.MemoryStream ms = new System.IO.MemoryStream(); s_random = RndNum(4); context.Session[ "random" ] = s_random; s_random = s_random.Substring(0, 1) + " " + s_random.Substring(1, 1) + " " + s_random.Substring(2, 1) + " " + s_random.Substring(3, 1); CreateImage(s_random, ref ms); context.Response.ClearContent(); context.Response.BinaryWrite(ms.ToArray()); context.Response.Flush(); context.Response.End(); } private void CreateImage( string checkCode, ref System.IO.MemoryStream ms) { int iwidth = ( int )(checkCode.Length * 18); System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 45); Graphics g = Graphics.FromImage(image); g.Clear(Color.White); //定义颜色 Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple }; //定义字体 //string[] font = {"Verdana","Microsoft Sans Serif","Comic Sans MS","Arial","宋体"}; Random rand = new Random(); //随机输出噪点 for ( int i = 0; i < 50; i++) { int x = rand.Next(image.Width); int y = rand.Next(image.Height); g.DrawRectangle( new Pen(Color.LightGray, 0), x, y, 1, 1); } //输出不同字体和颜色的验证码字符 for ( int i = 0; i < checkCode.Length; i++) { int cindex = rand.Next(7); int findex = rand.Next(5); Font font = new System.Drawing.Font( "Arial" , 24, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic)); Brush b = new System.Drawing.SolidBrush(c[cindex]); int ii = 4; if ((i + 1) % 2 == 0) { ii = 2; } g.DrawString(checkCode.Substring(i, 1), font, b, 3 + (i * 12), ii); } //画一个边框 g.DrawRectangle( new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1); //输出到浏览器 image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); g.Dispose(); image.Dispose(); } public static String RndNum( int VcodeNum) { String Vchar = "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[] VcArray = Vchar.Split( ',' ); String VNum = "" ; Random random = new Random(); for ( int i = 1; i <= VcodeNum; i++) { int iNum = 0; while ((iNum = Convert.ToInt32(VcArray.Length * random.NextDouble())) == VcArray.Length) { iNum = Convert.ToInt32(VcArray.Length * random.NextDouble()); } VNum += VcArray[iNum]; } return VNum; } public bool IsReusable { get { return false ; } } } |
备注:
onclick="this.src=this.src+'?'"
之前一直不明白为什么要加一个?号,于是去网上搜索,参考一下前辈们的见解:
【这是表示当前图片链接,在当前链接值的基础上添加了一个问号
譬如当前src="check.aspx",点击后就变成了"check.aspx?",继续点就会变成"check.aspx?????"
这个问号是没有实际意义的,它唯一的作用是向IE表明: 图片链接发生了变化,图片需要刷新.】
【GET:当客户端要从服务器中读取文档时,使用GET方法。GET方法要求服务器将URL定位的资源放在响应报文的数据部分,回送给客户端。使用GET方法时,请求参数和对应的值附加在URL后面,利用一个问号(“?”)代表URL的结尾与请求参数的开始,传递参数长度受限制。例如,/index.jsp?id=100&op=bind。
POST:当客户端给服务器提供信息较多时可以使用POST方法。POST方法将请求参数封装在HTTP请求数据中,以名称/值的形式出现,可以传输大量数据。
this.src=this.src+'?'是将this.src原值后加上?,以便向服务器发送一个新的GET方法,从而获取新的验证码】
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:https://www.cnblogs.com/AnneHan/p/5555605.html