99 lines
3.6 KiB
C#
99 lines
3.6 KiB
C#
using System;
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using System.Data;
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using System.Configuration;
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using System.Collections;
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using System.Drawing;
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using System.Web;
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using System.Web.Security;
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using System.Web.UI;
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using System.Web.UI.WebControls;
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using System.Web.UI.WebControls.WebParts;
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using System.Web.UI.HtmlControls;
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public partial class utils_showImage : System.Web.UI.Page
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{
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protected void Page_Load(object sender, EventArgs e)
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{
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// 创建一个包含随机内容的验证码文本
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System.Random rand = new Random();
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int len = rand.Next(2,4);
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char[] chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();
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System.Text.StringBuilder myStr = new System.Text.StringBuilder();
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for (int iCount = 0; iCount < len; iCount++)
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{
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myStr.Append(chars[rand.Next(chars.Length)]);
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}
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string text = myStr.ToString();
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// 保存验证码到 session 中以便其他模块使用
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this.Session["checkcode"] = text;
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Size ImageSize = Size.Empty;
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Font myFont = new Font("MS Sans Serif", 18);
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// 计算验证码图片大小
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using (Bitmap bmp = new Bitmap(10, 10))
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{
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using (Graphics g = Graphics.FromImage(bmp))
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{
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SizeF size = g.MeasureString(text, myFont, 10000);
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ImageSize.Width = (int)size.Width + 8;
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ImageSize.Height = (int)size.Height + 8;
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}
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}
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// 创建验证码图片
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using (Bitmap bmp = new Bitmap(ImageSize.Width, ImageSize.Height))
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{
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// 绘制验证码文本
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using (Graphics g = Graphics.FromImage(bmp))
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{
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g.Clear(Color.White);
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using (StringFormat f = new StringFormat())
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{
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f.Alignment = StringAlignment.Near;
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f.LineAlignment = StringAlignment.Center;
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f.FormatFlags = StringFormatFlags.NoWrap;
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g.DrawString(
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text,
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myFont,
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Brushes.Black,
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new RectangleF(
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0,
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0,
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ImageSize.Width,
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ImageSize.Height),
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f);
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}//using
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}//using
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// 制造噪声 杂点面积占图片面积的 30%
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int num = ImageSize.Width * ImageSize.Height * 30 / 100;
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for (int iCount = 0; iCount < num; iCount++)
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{
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// 在随机的位置使用随机的颜色设置图片的像素
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int x = rand.Next(ImageSize.Width);
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int y = rand.Next(ImageSize.Height);
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int r = rand.Next(255);
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int g = rand.Next(255);
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int b = rand.Next(255);
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Color c = Color.FromArgb(r, g, b);
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bmp.SetPixel(x, y, c);
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}//for
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// 输出图片
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System.IO.MemoryStream ms = new System.IO.MemoryStream();
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bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
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this.Response.ContentType = "image/png";
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ms.WriteTo(this.Response.OutputStream);
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ms.Close();
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}//using
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myFont.Dispose();
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}
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/// <summary>
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/// 检查指定的文本是否匹配验证码
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/// </summary>
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/// <param name="text">要判断的文本</param>
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/// <returns>是否匹配</returns>
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public static bool CheckCode(string text)
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{
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string txt = System.Web.HttpContext.Current.Session["checkcode"] as string;
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return text == txt;
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}
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}
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