验证码的生成

心已赠人 2022-09-19 14:26 189阅读 0赞

public class ValidateCode : System.Web.UI.Page  
 \{  
   private void Page\_Load( object sender, System.EventArgs e)  
  \{  
    this.CreateCheckCodeImage(GenerateCheckCode());  
  \}

\#region Web 窗体设计器生成的代码  
  override protected void OnInit(EventArgs e)  
  \{  
   //  
   // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。  
   //  
   InitializeComponent();  
   base.OnInit(e);  
  \}  
    
  /// <summary>  
  /// 设计器支持所需的方法 - 不要使用代码编辑器修改  
  /// 此方法的内容。  
  /// </summary>  
  private void InitializeComponent()  
  \{     
   this.Load += new System.EventHandler(this.Page\_Load);  
  \}  
  \#endregion

private string GenerateCheckCode()  
  \{  
   int number;  
   char code;  
   string checkCode = String.Empty;

System.Random random = new Random();

for(int i=0; i<5; i++)  
   \{  
    number = random.Next();

if(number % 2 == 0)  
     code = (char)('0' + (char)(number % 10));  
    else  
     code = (char)('A' + (char)(number % 26));

checkCode += code.ToString();  
   \}

Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));

return checkCode;  
  \}

private void CreateCheckCodeImage(string checkCode)  
  \{  
   if(checkCode == null || checkCode.Trim() == String.Empty)  
    return;

System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length \* 12.5)), 22);  
   Graphics g = Graphics.FromImage(image);

try  
   \{  
    //生成随机生成器  
    Random random = new Random();

//清空图片背景色  
    g.Clear(Color.White);

//画图片的背景噪音线  
    for(int i=0; i<25; i++)  
    \{  
     int x1 = random.Next(image.Width);  
     int x2 = random.Next(image.Width);  
     int y1 = random.Next(image.Height);  
     int y2 = random.Next(image.Height);

g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);  
    \}

Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));  
    System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);  
    g.DrawString(checkCode, font, brush, 2, 2);

//画图片的前景噪音点  
    for(int i=0; i<100; i++)  
    \{  
     int x = random.Next(image.Width);  
     int y = random.Next(image.Height);

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

//画图片的边框线  
    g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

System.IO.MemoryStream ms = new System.IO.MemoryStream();  
    image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);  
    Response.ClearContent();  
    Response.ContentType = "image/Gif";  
    Response.BinaryWrite(ms.ToArray());  
   \}  
   finally  
   \{  
    g.Dispose();  
    image.Dispose();  
   \}  
  \}  
 \}

假如以上验证码生成器页面名为：CheckCode.aspx，那么在登录页面中使用“<IMG>” 这个 HTML 元素来显示生成的验证码图片：<IMG src="CheckCode.aspx">  
　　在登录页面的登录按钮的处理事件中使用以下代码判断验证码：

private void btnLogin\_Click(object sender, System.Web.UI.ImageClickEventArgs e)  
  \{  
   if(Request.Cookies\["CheckCode"\] == null)  
   \{  
    lblMessage.Text = "您的浏览器设置已被禁用 Cookies，您必须设置浏览器允许使用 Cookies 选项后才能使用本系统。";  
    lblMessage.Visible = true;  
    return;  
   \}

if(String.Compare(Request.Cookies\[" CheckCode"\].Value, txtCheckCode.Text, true) != 0)  
   \{  
    lblMessage.Text = "验证码错误，请输入正确的验证码。";  
    lblMessage.Visible = true;  
     return;  
   \}  
  
  
  
  \}