asp.Net 一些常用的方法和类(3)

            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 < 60; 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(); 
        } 
    } 
 
    #endregion 
 
 
} 

清空缓存：

//清空客户端页面缓存 
public static void ClearClientPageCache() 
{ 
    HttpContext.Current.Response.Buffer = true; 
    HttpContext.Current.Response.Expires = 0; 
    HttpContext.Current.Response.ExpiresAbsolute = DateTime.Now.AddDays(-1); 
    HttpContext.Current.Response.AddHeader("pragma", "no-cache");