c#生成图片验证码

一般处理程序 ashx :它没有服务器控件，用response输出什么就是什么，一般作为文件来使用，放在aspx页面里使用

session:是用来存储数据的，设计一个服务器端的全局变量，在一般处理程序中，使用session需要引用命名空间，并继承接口

imagebutton用来显示验证码图片，通过?id=...来改变图片

 

一般处理程序ashx里的代码

<%@ WebHandler Language="C#" Class="Handler" %>



using System;

using System.Web;

using System.Drawing;

using System.Web.SessionState;

//引用的命名空间  

public class Handler : IHttpHandler, IRequiresSessionState

{

    public string charSet = "2,3,4,5,6,8,9,A,B,C,D,E,F,G,H,J,K,M,N,P,R,S,U,W,X,Y";

    public void ProcessRequest (HttpContext context)

    {

       

            string validateCode = CreateRandomCode(4);

            context.Session["ValidateCode"] = validateCode;

           CreateImage(validateCode, context);  

        

        //context.Response.ContentType = "text/plain";

        //context.Response.Write("Hello World");

        //string validateCode = CreateRandomCode(4);

        //context.Session["ValidateCode"] = validateCode;

        //CreateImage(validateCode, context);   



    }

 

    public bool IsReusable

    {

        get

        {

            return false;

        }

    }



    private string CreateRandomCode(int n)

    {

        string[] CharArray = charSet.Split(',');

        string randomCode = "";

        int temp = -1;

        Random rand = new Random();

        for (int i = 0; i < n; i++)

        {

            if (temp != -1)

            {

                rand = new Random(i * temp * ((int)DateTime.Now.Ticks));

            } int t = rand.Next(CharArray.Length - 1);

            if (temp == t)

            {

                return CreateRandomCode(n);

            } temp = t;

            randomCode += CharArray[t];

        }

        return randomCode;

    }





    //绘制验证码图片

    private void CreateImage(string checkCode, HttpContext context)

    {

        int iwidth = (int)(checkCode.Length * 13);

        System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 23);

        Graphics g = Graphics.FromImage(image);

        Font f = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Italic | System.Drawing.FontStyle.Bold));        // 前景色  



        Brush b = new System.Drawing.SolidBrush(Color.Black);        // 背景色       

        g.Clear(Color.White);        // 填充文字        

        g.DrawString(checkCode, f, b, 0, 1);        // 随机线条        

        Pen linePen = new Pen(Color.Gray, 0);

        Random rand = new Random();

        for (int i = 0; i < 5; i++)

        {

            int x1 = rand.Next(image.Width);

            int y1 = rand.Next(image.Height);

            int x2 = rand.Next(image.Width);

            int y2 = rand.Next(image.Height);

            g.DrawLine(linePen, x1, y1, x2, y2);

        }

        // 随机点        

        for (int i = 0; i < 30; i++)

        {

            int x = rand.Next(image.Width);

            int y = rand.Next(image.Height);

            image.SetPixel(x, y, Color.Gray);

        }

        // 边框       

        g.DrawRectangle(new Pen(Color.Gray), 0, 0, image.Width - 1, image.Height - 1);

        // 输出图片  

        System.IO.MemoryStream ms = new System.IO.MemoryStream();

        image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);

        context.Response.ClearContent();

        context.Response.ContentType = "image/Jpeg";

        context.Response.BinaryWrite(ms.ToArray());



        g.Dispose();

        image.Dispose();

    }    





}

aspx里的代码

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Drawing;

using System.IO;





public partial class _Default : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {



    }

 



protected void Button1_Click(object sender, EventArgs e)

{

    if (TextBox1.Text.ToUpper().Trim() == Session["ValidateCode"].ToString().ToUpper().Trim())

        {

           Response.Write("<script>alert('验证码相同')</script>");

        }

else

{

   Response.Write("<script>alert('验证码不正确')</script>");

}





}

    //看不清，换一张

protected void Button2_Click(object sender, EventArgs e)

{

    //通过超链接传值来改变验证码图片

    ImageButton1.ImageUrl = "Handler.ashx?id="+new Random().Next(62);

}

}

aspx界面里的代码

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>



<!DOCTYPE html>

<script runat="server">



   

   

</script>





<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>

    <title></title>

</head>

<body>

    <form id="form1" runat="server">

    <div>

    

        <br />

        <asp:ScriptManager ID="ScriptManager1" runat="server">

        </asp:ScriptManager>

        <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="登录" />

    

        <br />

        <br />

&nbsp;<br />

&nbsp;&nbsp;

        <asp:Label ID="Label1" runat="server" Text="验证码"></asp:Label>

&nbsp;&nbsp;

        <asp:TextBox ID="TextBox1" runat="server" Height="32px"></asp:TextBox>

&nbsp;&nbsp;&nbsp;&nbsp;<asp:UpdatePanel ID="UpdatePanel1" runat="server">

            <ContentTemplate>

                <asp:Button ID="Button2" runat="server" OnClick="Button2_Click" Text="看不清 换一张" />







                重点看这一句

               <asp:ImageButton ID="ImageButton1" runat="server" ImageUrl="Handler.ashx" />







            </ContentTemplate>

        </asp:UpdatePanel>

&nbsp;&nbsp;&nbsp;&nbsp

        &nbsp;

 

 



       

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    </div>

    </form>

</body>

</html>