asp.net 验证码 实现

第1种.

using System;using System.Data;using System.Configuration;using System.Collections;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;using System.Drawing.Imaging;using System.Drawing.Drawing2D;using System.Drawing;public partial class fetchcode : System.Web.UI.Page{ protected void Page_Load(object sender, EventArgs e) { Random rd = new Random(); //创建随机数对象 //以下4行,产生由6个字母和数字组成的一个字符串 string str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789我你他"; string my51aspx = ""; for (int i = 0; i < 4; i++) { my51aspx = my51aspx + str.Substring(rd.Next(39), 1); } //验证码值存放到Session中用来比较 Session["Valid"] = my51aspx; //以下三句,通过随机找一个现有图象产生一个画布Bitmap string bgFilePath = Server.MapPath(".//images//bg" + new Random().Next(5) + ".jpg");//随机找个图象 // string bgFilePath = Server.MapPath(".//images//bg2" + ".jpg");//随机找个图象 System.Drawing.Image imgObj = System.Drawing.Image.FromFile(bgFilePath); Bitmap newBitmap = new Bitmap(imgObj, 90, 30);//建立位图对象 Graphics g = Graphics.FromImage(newBitmap);//根据上面创建的位图对象创建绘图面 Color[] fore = { Color.Black ,Color.Red}; SolidBrush brush = new SolidBrush(fore[new Random().Next(2)]);//设置画笔颜色 //定义一个含10种字体的数组 String[] fontFamily = { "Arial", "Verdana", "Comic Sans MS", "Impact", "Haettenschweiler", "Lucida Sans Unicode", "Garamond", "Courier New", "Book Antiqua", "Arial Narrow" }; //通过循环,绘制每个字符, for (int a = 0; a < my51aspx.Length; a++) { Font textFont = new Font(fontFamily[rd.Next(9)], 15, FontStyle.Regular);//字体随机,字号大小10,加粗 //每次循环绘制一个字符,设置字体格式,画笔颜色,字符相对画布的X坐标,字符相对画布的Y坐标 g.DrawString(my51aspx.Substring(a, 1), textFont, brush, 10 + a * 18, 5); } //保存画的图片到输出流中 newBitmap.Save(Response.OutputStream, ImageFormat.Gif); }}

第2种：

using System;using System.Collections;using System.ComponentModel;using System.Data;using System.Web;using System.Web.SessionState;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.HtmlControls;using System.Drawing;using System.Drawing.Imaging;using System.Drawing.Text;/**///// <summary>/// 页面验证码程序/// 使用：在页面中加入HTML代码 <img src="VerifyCode.aspx" mce_src="VerifyCode.aspx">/// </summary>public partial class VerifyCode : System.Web.UI.Page{ static string[] FontItems = new string[]{ "Arial", // "Helvetica", // "Geneva", // "sans-serif", //"Verdana" }; static Brush[] BrushItems = new Brush[]{ // Brushes.OliveDrab //Brushes.ForestGreen Brushes.DarkCyan // Brushes.LightSlateGray, // Brushes.RoyalBlue, // Brushes.SlateBlue, // Brushes.DarkViolet, // Brushes.MediumVioletRed, // Brushes.IndianRed, // Brushes.Firebrick, // Brushes.Chocolate, // Brushes.Peru, // Brushes.Goldenrod // }; static string[] BrushName = new string[]{ // "OliveDrab" // "ForestGreen" "DarkCyan" //"LightSlateGray", //"RoyalBlue", //"SlateBlue", //"DarkViolet", //"MediumVioletRed", //"IndianRed", //"Firebrick", //"Chocolate", //"Peru", //"Goldenrod" }; private static Color BackColor = Color.White; private static Pen BorderColor = Pens.DarkGray; private static int Width = 52; private static int Height = 21; private Random _random; private string _code; private int _brushNameIndex; override protected void OnInit(EventArgs e) { // // CODEGEN: This call is required by the ASP.NET Web Form Designer. // //InitializeComponent(); //base.OnInit(e); } /**//**//**//// <summary> /// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// </summary> private void InitializeComponent() { //this.Load += new System.EventHandler(this.Page_Load); } /**//// <summary> /// /// </summary> /// <param name="sender"></param> /// <param name="e"></param> public void Page_Load(object sender, System.EventArgs e) { if (!IsPostBack) { // // TODO : initialize // this._random = new Random(); this._code = GetRandomCode(); // // TODO : use Session["code"] save the VerifyCode // Session["code"] = this._code; // // TODO : output Image // this.SetPageNoCache(); this.OnPaint(); } } /**//**//**//// <summary> /// 设置页面不被缓存 /// </summary> private void SetPageNoCache() { Response.Buffer = true; Response.ExpiresAbsolute = System.DateTime.Now.AddSeconds(-1); Response.Expires = 0; Response.CacheControl = "no-cache"; Response.AppendHeader("Pragma","No-Cache"); } /**//**//**//// <summary> /// 取得一个 4 位的随机码 /// </summary> /// <returns></returns> private string GetRandomCode() { return Guid.NewGuid().ToString().Substring(0, 4); } /**//**//**//// <summary> /// 随机取一个字体 /// </summary> /// <returns></returns> private Font GetFont() { int fontIndex = _random.Next(0, FontItems.Length); FontStyle fontStyle = GetFontStyle(_random.Next(0, 2)); return new Font(FontItems[fontIndex], 12, fontStyle); } /**//**//**//// <summary> /// 取一个字体的样式 /// </summary> /// <param name="index"></param> /// <returns></returns> private FontStyle GetFontStyle(int index) { switch (index) { case 0: // return FontStyle.Italic; case 1: return FontStyle.Bold; default: return FontStyle.Regular; } } /**//**//**//// <summary> /// 随机取一个笔刷 /// </summary> /// <returns></returns> private Brush GetBrush() { int brushIndex = _random.Next(0, BrushItems.Length); _brushNameIndex = brushIndex; return BrushItems[brushIndex]; } /**//**//**//// <summary> /// 绘画事件 /// </summary> private void OnPaint() { Bitmap objBitmap = null; Graphics g = null; try { objBitmap = new Bitmap(Width, Height); g = Graphics.FromImage(objBitmap); Paint_Background(g); Paint_Text(g); Paint_TextStain(objBitmap); Paint_Border(g); objBitmap.Save(Response.OutputStream, ImageFormat.Gif); Response.ContentType = "image/gif"; } catch{} finally { if (null != objBitmap) objBitmap.Dispose(); if (null != g) g.Dispose(); } } /**//**//**//// <summary> /// 绘画背景颜色 /// </summary> /// <param name="g"></param> private void Paint_Background(Graphics g) { g.Clear(BackColor); } /**//**//**//// <summary> /// 绘画边框 /// </summary> /// <param name="g"></param> private void Paint_Border(Graphics g) { g.DrawRectangle(BorderColor, 0, 0, Width - 1, Height - 1); } /**//**//**//// <summary> /// 绘画文字 /// </summary> /// <param name="g"></param> private void Paint_Text(Graphics g) { g.DrawString(_code, GetFont(), GetBrush(), 3, 1); } /**//**//**//// <summary> /// 绘画文字噪音点 /// </summary> /// <param name="g"></param> private void Paint_TextStain(Bitmap b) { for (int n=0; n<30; n++) { int x = _random.Next(Width); int y = _random.Next(Height); b.SetPixel(x, y, Color.FromName(BrushName[_brushNameIndex])); } }}