使用一般处理程序生成验证码

在 IHttpHandler 的实现中访问 Session，此实现必须同时实现标记接口 System.Web.SessionState.IRequiresSessionState，才可以对 Session 进行读写

 

public class Handler : IHttpHandler,System.Web.SessionState.IRequiresSessionState { public void ProcessRequest (HttpContext context) { string backImagePath = ""; string path = context.Server.MapPath(backImagePath); System.Drawing.Image image = System.Drawing.Image.FromFile(path); // 使用随机数生成随机数 //System.Random random = new Random(); //int code = random.Next(1000, 10000); //string codeString = code.ToString(); // 借助 Guid 生成随机验证码 System.Guid guid = System.Guid.NewGuid(); string codeString = guid.ToString().Substring(0, 4); // 使用会话状态 context.Session["Code"] = codeString; using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image)) { g.DrawString(codeString, new System.Drawing.Font("Arial", 14), System.Drawing.Brushes.Blue, 3, 3); } context.Response.ContentType = "image/jpeg"; image.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg); } public bool IsReusable { get { return false; } } }

在页面中<asp:Image ID="Image1" runat="server" ImageUrl="~/Handler.ashx" /><br />
请输入验证码：<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:CustomValidator ID="CustomValidator1" runat="server" ControlToValidate="TextBox1"
ErrorMessage=" 验证码错误！ "
OnServerValidate="CustomValidator1_ServerValidate"></asp:CustomValidator>

 

 

protected void CustomValidator1_ServerValidate(object source,ServerValidateEventArgs args) { // 取得原来保存在 Session 中的验证码 string serverCode = this.Session["Code"] as string; // 用户输入的内容，不通过控件，直接通过参数 // string userCode = this.TextBox1.Text; string userCode = args.Value; bool result = (serverCode == userCode); // 设置到自定义验证中 args.IsValid = result; }

 

然后就可以在像BUTTON中的CLICK事件通过IsValid 来判断是否通过验证。

 

protected void LinkButton1_Click(object sender, EventArgs e) { // 检查是否通过验证 if (this.IsValid) { this.Label1.Text = "通过验证"; } }