asp.net 验证码_彩色

转自 清清月儿：http://blog.csdn.net/21aspnet/archive/2007/03/19/1534319.aspx

略有修改

<img id="imgCode" alt="点击刷新验证码" height="23" src="CodeNubImg.aspx" style="cursor: pointer" width="52" onclick="this.src=this.src+'?'" />if (this.txtCode.Text.ToUpper() == Session["CheckCode"].ToString().ToUpper()) { } using System;using System.Web;using System.Drawing;public partial class CodeNubImg : System.Web.UI.Page{ protected void Page_Load(object sender, EventArgs e) { HttpContext.Current.Session["CheckCode"] = RndNum(4); CreateImages(HttpContext.Current.Session["CheckCode"].ToString()); } /// <summary> /// 生成验证图片 /// </summary> /// <param name="checkCode">验证字符</param> private void CreateImages(string checkCode) { int iwidth = (int)(checkCode.Length * 13); System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 23); 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 f = new System.Drawing.Font(font[findex], 10, System.Drawing.FontStyle.Bold); Brush b = new System.Drawing.SolidBrush(c[cindex]); int ii = 4; if ((i + 1) % 2 == 0) { ii = 2; } g.DrawString(checkCode.Substring(i, 1), f, 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 System.IO.MemoryStream ms = new System.IO.MemoryStream(); image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); HttpContext.Current.Response.ClearContent(); //Response.ClearContent(); HttpContext.Current.Response.ContentType = "image/Jpeg"; HttpContext.Current.Response.BinaryWrite(ms.ToArray()); g.Dispose(); image.Dispose(); } /// <summary> /// 生成随机的字母 /// </summary> /// <param name="VcodeNum">生成字母的个数</param> /// <returns>string</returns> private string RndNum(int VcodeNum) { string Vchar = "0,1,2,3,4,5,6,7,8,9"; string[] VcArray = Vchar.Split(','); string VNum = ""; //由于字符串很短，就不用StringBuilder了 int temp = -1; //记录上次随机数值，尽量避免生产几个一样的随机数 //采用一个简单的算法以保证生成随机数的不同 Random rand = new Random(); for (int i = 1; i < VcodeNum + 1; i++) { if (temp != -1) { rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks)); } int t = rand.Next(VcArray.Length); if (temp != -1 && temp == t) { return RndNum(VcodeNum); } temp = t; VNum += VcArray[t]; } return VNum; } }