asp.net中3种验证码示例(数字 数字字母混和 汉字)

后端开发|C#.Net教程

验证码

后端开发-C#.Net教程

效果如图所示：

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Default.aspx

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using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!Page.IsPostBack) { string getNums = GetVali(); Label1.Text = getNums; } } /// /// 返回生成的随机数 public string GetVali() { string strsvali = "0,1,2,3,4,5,6,7,8,9"; string[] ValiArray = strsvali.Split(,); string ReturnNum = ""; int nums = -1; Random vrand = new Random(); for (int n = 1; n < 5; n++) { if (nums != -1) { vrand = new Random(n * nums * unchecked((int)DateTime.Now.Ticks)); } int t = vrand.Next(10); nums = t; ReturnNum += ValiArray[t]; } Session["Valid"] = ReturnNum; return ReturnNum; } protected void btnOK_Click(object sender, EventArgs e) { if (Session["Valid"].ToString() == TextBox3.Text) { ClientScript.RegisterStartupScript(this.GetType(),"ss","alert(您已经成功通过登录验证！)"); } else { ClientScript.RegisterStartupScript(this.GetType(), "ss", "alert(您输入的验证码错误！)"); } } }

GetValid.aspx

(可以直接将该页面作为源赋值给ImageUrl)

前台为空，后台代码如下：

using System; using System.Collections; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Xml.Linq; using System.Text; using System.Drawing; public partial class GetValid : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { string validateNum = GetValids(); //成生4位随机字符串 CreateImage(validateNum); //将生成的随机字符串绘成图片 Session["ValidNums"] = validateNum; //保存验证码 } } public static string GetValids() { //获取GB2312编码页（表） Encoding gb = Encoding.GetEncoding("gb2312"); //调用函数产生4个随机中文汉字编码 object[] bytes = CreateRegionCode(4); //根据汉字编码的字节数组解码出中文汉字 string s = String.Empty; foreach (object byt in bytes) { string str1 = gb.GetString((byte[])Convert.ChangeType(byt, typeof(byte[]))); s = s + str1; } //输出的控制台 return s; } public static object[] CreateRegionCode(int strlength) { //定义一个字符串数组储存汉字编码的组成元素 string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" }; Random rnd = new Random(); //定义一个object数组用来 object[] bytes = new object[strlength]; /*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中 每个汉字有四个区位码组成 区位码第1位和区位码第2位作为字节数组第一个元素 区位码第3位和区位码第4位作为字节数组第二个元素 */ for (int i = 0; i < strlength; i++) { //区位码第1位 int r1 = rnd.Next(11, 14); string str_r1 = rBase[r1].Trim(); //区位码第2位 rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i); //更换随机数发生器的种子避免产生重复值 int r2; if (r1 == 13) { r2 = rnd.Next(0, 8); } else { r2 = rnd.Next(0, 16); } string str_r2 = rBase[r2].Trim(); //区位码第3位 rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i); int r3 = rnd.Next(10, 16); string str_r3 = rBase[r3].Trim(); //区位码第4位 rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i); int r4; if (r3 == 10) { r4 = rnd.Next(1, 16); } else if (r3 == 15) { r4 = rnd.Next(0, 15); } else { r4 = rnd.Next(0, 16); } string str_r4 = rBase[r4].Trim(); //定义两个字节变量存储产生的随机汉字区位码 byte byte1 = Convert.ToByte(str_r1 + str_r2, 16); byte byte2 = Convert.ToByte(str_r3 + str_r4, 16); //将两个字节变量存储在字节数组中 byte[] str_r = new byte[] { byte1, byte2 }; //将产生的一个汉字的字节数组放入object数组中 bytes.SetValue(str_r, i); } return bytes; } //生成图片 private void CreateImage(string validateNum) { if (validateNum == null || validateNum.Trim() == String.Empty) return; //生成Bitmap图像 System.Drawing.Bitmap image = new System.Drawing.Bitmap(validateNum.Length * 12 + 10, 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.Coral), x1, y1, x2, y2); } Font font = new System.Drawing.Font("Arial", 8); 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(validateNum, 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(); //将图像保存到指定的流 image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); Response.ClearContent(); Response.ContentType = "image/Gif"; Response.BinaryWrite(ms.ToArray()); } finally { g.Dispose(); image.Dispose(); } } }

ValidNums.aspx

(可以直接将该页面作为源赋值给ImageUrl)

前台为空，后台代码如下：

using System; using System.Collections; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Xml.Linq; using System.Drawing; public partial class ValidNums : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { string validateNum = CreateRandomNum(4); //成生4位随机字符串 CreateImage(validateNum); //将生成的随机字符串绘成图片 Session["ValidNums"] = validateNum; //保存验证码 } } //生成随机字符串 private string CreateRandomNum(int NumCount) { string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z"; string[] allCharArray = allChar.Split(,);//拆分成数组 string randomNum = ""; int temp = -1;//记录上次随机数的数值，尽量避免产生几个相同的随机数 Random rand = new Random(); for (int i = 0; i < NumCount; i++) { if (temp != -1) { rand = new Random(i * temp * ((int)DateTime.Now.Ticks)); } int t = rand.Next(35); if (temp == t) { return CreateRandomNum(NumCount); } temp = t; randomNum += allCharArray[t]; } return randomNum; } //生成图片 private void CreateImage(string validateNum) { if (validateNum == null || validateNum.Trim() == String.Empty) return; //生成Bitmap图像 System.Drawing.Bitmap image = new System.Drawing.Bitmap(validateNum.Length * 12 + 10, 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.Coral), 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(validateNum, 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(); //将图像保存到指定的流 image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); Response.ClearContent(); Response.ContentType = "image/Gif"; Response.BinaryWrite(ms.ToArray()); } finally { g.Dispose(); image.Dispose(); } } }

以上是3种验证码的全部代码。

另外也可以使用ashx请求验证码的方式，本示例仅使用Session存值处理。

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