新建一般处理程序：veify.ashx
<%@ WebHandler Language="C#" Class="verify" %> using System; using System.Web; using System.Text; using System.IO; using System.Drawing; using System.Drawing.Imaging; public class verify : IHttpHandler, System.Web.SessionState.IRequiresSessionState { public void ProcessRequest(HttpContext context) { Code gif = new Code();//初始化验证码生成类 string valid = "";//定义随机数 MemoryStream ms = gif.Create(out valid);//获取包括验证码图片的内存流 context.Session["gif"] = valid;//验证码存储在Session中，供验证。 context.Response.ClearContent();//清空输出流 context.Response.ContentType = "image/png";//输出流的格式 context.Response.BinaryWrite(ms.ToArray());//输出 context.Response.End(); } public bool IsReusable { get { return false; } } } public class Code { /// <summary> /// 该方法用于生成指定位数的随机数 /// </summary> /// <param name="VcodeNum">参数是随机数的位数</param> /// <returns>返回一个随机数字符串</returns> private string RndNum(int VcodeNum) { //验证码可以显示的字符集合 //string Vchar = "1,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,p,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,P,Q" + // ",R,S,T,U,V,W,X,Y,Z"; string Vchar = "1,2,3,4,5,6,7,8,9";//=================================================这里使用纯数字 string[] VcArray = Vchar.Split(new Char[] { ',' });//拆分成数组 string VNum = "";//产生的随机数 int temp = -1;//记录上次随机数值，尽量避避免生产几个一样的随机数 Random rand = new Random(); //采用一个简单的算法以保证生成随机数的不同 for (int i = 1; i < VcodeNum + 1; i++) { if (temp != -1) { rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));//初始化随机类 } //int t = rand.Next(61);//获取随机数 int t = rand.Next(9);//======================================================与VcArray定义的长度匹配 if (temp != -1 && temp == t) { return RndNum(VcodeNum);//如果获取的随机数重复，则递归调用 } temp = t;//把本次产生的随机数记录起来 VNum += VcArray[t];//随机数的位数加一 } return VNum; } /// <summary> /// 该方法是将生成的随机数写入图像文件 /// </summary> /// <param name="VNum">VNum是一个随机数</param> public MemoryStream Create(out string VNum) { VNum = RndNum(4); Bitmap Img = null; Graphics g = null; MemoryStream ms = null; System.Random random = new Random(); //验证码颜色集合 Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple }; //验证码字体集合 string[] fonts ={ "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" }; //定义图像的大小，生成图像的实例 Img = new Bitmap((int)VNum.Length * 18, 32); g = Graphics.FromImage(Img);//从Img对象生成新的Graphics对象 g.Clear(Color.White);//背景设为白色 //在随机位置画背景点 for (int i = 0; i < 100; i++) { int x = random.Next(Img.Width); int y = random.Next(Img.Height); g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1); } //验证码绘制在g中 for (int i = 0; i < VNum.Length; i++) { int cindex = random.Next(7);//随机颜色索引值 int findex = random.Next(5);//随机字体索引值 Font f = new System.Drawing.Font(fonts[findex], 20, System.Drawing.FontStyle.Bold);//字体======================字体大小 Brush b = new System.Drawing.SolidBrush(c[cindex]);//颜色 int ii = 4; if ((i + 1) % 2 == 0)//控制验证码不在同一高度 { ii = 2; } g.DrawString(VNum.Substring(i, 1), f, b, 3 + (i * 12), ii);//绘制一个验证字符 } ms = new MemoryStream();//生成内存流对象 Img.Save(ms, ImageFormat.Jpeg);//将此图像以Png图像文件的格式保存到流中 //回收资源 g.Dispose(); Img.Dispose(); return ms; } }
html代码：
<asp:TextBox ID="txtVerify" runat="server" MaxLength="4" Width="100px" CssClass="txtin2" Height="18px"></asp:TextBox>
<img src='verify.ashx' style="100px;height:30px" id="verify"/>
<a href='javascript:verify();'>看不清，换一张</a>
js换一张代码：
function verify(){ $("#verify").attr("src","verify.ashx"); }
后台代码：
if (txtVerify.Text == "") { this.ClientScript.RegisterStartupScript(this.GetType(), "scriptKey", "alert('验证码不能为空！')", true); } else if (String.Compare(Session["gif"].ToString(), txtVerify.Text, true) != 0) { txtVerify.Text = ""; this.ClientScript.RegisterStartupScript(this.GetType(), "scriptKey", "alert('验证码有误,请重新输入正确的验证码！')", true); } else { //通过验证 }
如图，可以自定义字符
