登陆界面验证码设置

先设置一个登陆界面：

<div class="reb">
                    验证码：
                    <input id="txtU_Check" type="text" runat="server" style=" 85px;" maxlength="5" />
                    <img id="ValidateImg" align="absmiddle" title="看不清？点击更换" alt="看不清？点击更换" src="ValidateImg.aspx"
                        style="cursor: pointer; vertical-align: middle;" onclick="this.src=this.src+'?'" />
                </div>

设置一个空白页面：VateImage.aspx，在这个页面用来调用验证码生成的类的方法： 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

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

{    

protected void Page_Load(object sender, EventArgs e)    

{        

ValidateCode.CreateCheckCodeImage();    

}

}

建立画验证码类：ValidateCode  代码如下

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Drawing;

using System.Drawing.Drawing2D;

using System.IO;

using System.Drawing.Imaging;

/// <summary>

///ValidateCode 的摘要说明

///生成验证校验

/// </summary>

public class ValidateCode

{  public ValidateCode()  

{   

//   //TODO: 在此处添加构造函数逻辑   //

 }

    /// <summary>     /// 创建验证码图片     ///

</summary>    

public static void CreateCheckCodeImage()    

{        

CreateCheckCodeImage(GenerateCheckCode());    

}    

/// <summary>    

/// 创建验证码图片    

/// </summary>    

/// <param name="checkCode"></param>    

private static void CreateCheckCodeImage(string checkCode)    

{         if ((checkCode != null) && !(checkCode.Trim() == string.Empty))        

{             Bitmap image = new Bitmap((int)Math.Ceiling((double)(checkCode.Length * 12.5)), 0x16);            

Graphics graphics = Graphics.FromImage(image);            

try            

{                

int num;                

Random random = new Random();                

graphics.Clear(Color.White);                

for (num = 0; num < 0x19; num++)                

{                    

int num2 = random.Next(image.Width);                   

 int num3 = random.Next(image.Width);                    

int num4 = random.Next(image.Height);                    

int num5 = random.Next(image.Height);                    

graphics.DrawLine(new Pen(Color.Silver), num2, num4, num3, num5);                

}                

Font font = new Font("Arial", 12f, FontStyle.Italic | FontStyle.Bold);                

LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);                

graphics.DrawString(checkCode, font, brush, (float)2f, (float)2f);                

for (num = 0; num < 100; num++)                

{                    

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

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

image.SetPixel(x, y, Color.FromArgb(random.Next()));                

}               

  graphics.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);                

MemoryStream stream = new MemoryStream();                

image.Save(stream, ImageFormat.Gif);                

HttpContext.Current.Response.ClearContent();                

HttpContext.Current.Response.ContentType = "image/Gif";                

HttpContext.Current.Response.BinaryWrite(stream.ToArray());            

}            

catch (Exception exception)            

{                

HttpContext.Current.Response.Redirect("ErrorMessage.aspx@Error=" + exception);            

}            

finally            

{                

graphics.Dispose();                

image.Dispose();            

}        

}    

}

/// <summary>    

/// 生成验证码    

/// </summary>    

/// <returns></returns>    

private static string GenerateCheckCode()    

{        

string str = getRodomNum();        

HttpContext.Current.Session.Add("CheckCode", str);        

return str;    

}    

/// <summary>    

/// 英文字符    

/// </summary>    

/// <returns></returns>    

private static string GetEngLish()    

{        

string[] strArray = new string[] {         "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "M", "L", "N", "O", "P",         "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"      };        

return strArray[GetMes.Random(0, 0x19)];    

}

private static string getRodomNum()    

{        

return GetMes.Random(0x3e8, 0x270f).ToString();    

}

}