前台代码
<body>
<form id="form1" runat="server">
<div>
<br />
<br />
<%--用户输入的文本框--%>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<%--验证码图片--%>
<img id="yzm1" src="YZM.aspx" /><br />
<%--验证按钮--%>
<asp:Button ID="Button1" runat="server" Text="验证" />
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label><br />
<asp:Label ID="Label2" runat="server" Text="Label"></asp:Label>
</div>
</form>
</body>
</html>
<script type="text/javascript">
//JS代码是点击图片就刷新验证码
var a = 0;
document.getElementById("yzm1").onclick = function () {
this.src = "yzm.aspx?a=" + a;
a++;
}
</script>
后台代码
protected void Page_Load(object sender, EventArgs e) { Button1.Click += Button1_Click; } void Button1_Click(object sender, EventArgs e) { Label2.Text = Session["YZM"].ToString(); if (TextBox1.Text == Session["YZM"].ToString()) Label1.Text = "正确！！！"; else Label1.Text = "错误！！！！！！！"; }
验证码要单独放到一个页面中
验证码后台代码
protected void Page_Load(object sender, EventArgs e) { //创建一个颜色集 List<Color> clist = new List<Color>(); clist.Add(Color.Red); clist.Add(Color.Firebrick); clist.Add(Color.LawnGreen); clist.Add(Color.Goldenrod); clist.Add(Color.Cyan); clist.Add(Color.DarkSlateBlue); clist.Add(Color.Indigo); //创建一个随机变量 Random r = new Random(); string s = ""; //添加随机数 string all = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmeopqrstuvwxyz0123456789"; //产生四个随机数 for (int i = 0; i < 4; i++) { s += all.Substring(r.Next(0, all.Length), 1); } Session["YZM"] = s; //放置验证码的图片 Bitmap img = new Bitmap(120, 60); Graphics g2 = Graphics.FromImage(img); //随机背景色 Brush b2 = new SolidBrush(clist[r.Next(0, clist.Count)]); g2.FillRectangle(b2, 0, 0, 120, 60); Graphics g = Graphics.FromImage(img); Font f = new Font("微软雅黑", 30); Brush b = new SolidBrush(Color.Red); g.DrawString(s, f, b, new PointF(0, 0)); //绘制线条，对验证码进行遮罩 for (int i = 0; i < 8; i++) { Graphics g3 = Graphics.FromImage(img); Pen p3 = new Pen(new SolidBrush(clist[r.Next(0, clist.Count)]), r.Next(2, 5)); g3.DrawLine(p3, new Point(r.Next(0, 120), r.Next(0, 60)), new Point(r.Next(0, 120), r.Next(0, 60))); } img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Png); }