[ASP.NET]验证码生成

 

验证码是现在大多数网站、论坛用到的为防止非法登录和非法提交信息的一种方法，其实它的实现并不复杂。下面就举个简单例子做一说明，生成的是包含字母和数字组合的验证码。

      首先在一个测试页面上，放一个img标记，然后将它的src属性指向一个验证码页面，用来得到输出的验证码图片的二进制流。接下来在验证码页面的Page_Load方法中调用一个验证码类的CreateValidateGraphic方法就可以了，这个方法需要传一个Page类型的参数。大体实现过程就是这样，另外如果要更换一张验证码图片，可以点击一下“刷新”，后附相关代码。

 

 ----------测试页面 Test1.aspx----------

刷新

----------验证码页面后台文件 ValidateCode.aspx.cs---------- 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 Solution.PublicLib; public partial class Test_ValidateCode : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { ValidateCode vc = new ValidateCode(146, 37, 5, 17f); vc.CreateValidateGraphic(this); Session["ValidateCodes"] = vc.ValidateCodes; } } ----------验证码类 ValidateCode.cs---------- using System; using System.Collections.Generic; using System.Text; using System.Drawing; using System.Drawing.Imaging; using System.Web.UI; using System.Drawing.Drawing2D; using System.IO; namespace Solution.PublicLib { ///

/// 验证码类 ///

public class ValidateCode { //验证码图片的长度 private int _imageWidth = 0; //验证码图片的高度 private int _imageHeight = 0; //验证码字符串的长度 private int _codeLength = 0; //新字体的全身大小（以磅值为单位） private float _emSize = 0f; //存放所有验证码字符串的数组 屏蔽"0"和"O" private string[] _fullCodes ={ "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" }; //存放生成的验证码字符串的数组 private string[] _validateCodes = null; ///

/// 验证码类的构造函数 ///

/// 验证码图片的长度 /// 验证码图片的高度 /// 验证码字符串的长度 /// 新字体的全身大小 public ValidateCode(int imageWidth, int imageHeight, int codeLength, float emSize) { _imageWidth = imageWidth; _imageHeight = imageHeight; _codeLength = codeLength; _emSize = emSize; } ///

/// 新字体的全身大小 ///

public float EmSize { get { return _emSize; } } ///

/// 验证码图片的长度 ///

public int ImageWidth { get { return _imageWidth; } } ///

/// 验证码图片的高度 ///

public int ImageHeight { get { return _imageHeight; } } ///

/// 验证码字符串的长度 ///

public int CodeLength { get { return _codeLength; } } ///

/// 验证码数组 ///

public String[] ValidateCodes { get { return _validateCodes; } } ///

/// 生成验证码字符串 ///

/// private string CreateValidateString() { string validateStr = ""; string[] validateCodes = new string[_codeLength]; //生成起始序列值 int seekSeek = unchecked((int)DateTime.Now.Ticks); Random seekRand = new Random(seekSeek); int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - _codeLength * 10000); int[] seeks = new int[_codeLength]; for (int i = 0; i < _codeLength; i++) { beginSeek += 10000; seeks[i] = beginSeek; } for (int i = 0; i < _codeLength; i++) { Random rnd = new Random(seeks[i]); int index = rnd.Next(0, _fullCodes.Length); validateCodes[i] = _fullCodes[index]; } for (int i = 0; i < _codeLength; i++) { validateStr += validateCodes[i].ToString() + " "; } _validateCodes = validateCodes; return validateStr; } ///

/// 输出验证码图片 ///

/// 要输出到的page对象 public void CreateValidateGraphic(Page containsPage) { string validateStr = CreateValidateString(); //Bitmap image = new Bitmap((int)Math.Ceiling(validateNum.Length * 12.5), 22); Bitmap image = new Bitmap(_imageWidth, _imageHeight); 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); //画图片的干扰线 //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 Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic)); //Font font = new Font("Comic Sans MS", 18, (FontStyle.Bold | FontStyle.Italic)); Font font = new Font("Comic Sans MS", _emSize, (FontStyle.Bold));//| FontStyle.Italic //LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true); LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.FromArgb(126, 190, 202), Color.FromArgb(126, 190, 202), 1.2f, true); //g.DrawString(validateNum, font, brush, 3, 2); g.DrawString(validateStr, font, brush, 5, 2); //画图片的前景干扰点 //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); //保存图片数据 MemoryStream stream = new MemoryStream(); image.Save(stream, ImageFormat.Jpeg); //输出图片 containsPage.Response.Clear(); containsPage.Response.ContentType = "image/jpeg"; containsPage.Response.BinaryWrite(stream.ToArray()); } finally { g.Dispose(); image.Dispose(); } } } }