介绍生成两种类型的图形验证码: 1.普通的随机字符串; 2.随机运算表达式
图形验证码类:
/// <summary>
/// 图形验证码类
/// </summary>
public class PicCaptcha
{
#region Constructed Methods
/// <summary>
/// 默认构造方法
/// </summary>
public PicCaptcha()
{
}
/// <summary>
///构造方法
/// </summary>
/// <param name="cpatchaType">验证码类型</param>
public PicCaptcha(CaptchaType cpatchaType)
{
this.CaptchaType = cpatchaType;
}
/// <summary>
/// 构造方法
/// </summary>
/// <param name="captchaType">验证码类型</param>
/// <param name="width">图形宽度</param>
/// <param name="height">图形高度</param>
public PicCaptcha(CaptchaType captchaType, int width, int height)
: this(captchaType)
{
this.Width = width;
this.Height = height;
}
/// <summary>
/// 构造方法
/// </summary>
/// <param name="captchaType">验证码类型</param>
/// <param name="width">图形宽度</param>
/// <param name="height">图形高度</param>
/// <param name="fontSize">字体大小</param>
public PicCaptcha(CaptchaType captchaType, int width, int height, int fontSize)
: this(captchaType, width, height)
{
this.FontSize = fontSize;
}
#endregion
#region Fields
private int _width = 80; //default width
private int _height = 25; //default height
private int _fontSize = 16; //default fontSize
private CaptchaType _captchaType = CaptchaType.RandomType; //default captchaType
#endregion
#region Properties
/// <summary>
/// 验证码图形宽度
/// </summary>
public int Width
{
get { return _width; }
set { _width = value; }
}
/// <summary>
/// 验证码图形高度
/// </summary>
public int Height
{
get { return _height; }
set { _height = value; }
}
/// <summary>
/// 验证码字体大小
/// </summary>
public int FontSize
{
get { return _fontSize; }
set { _fontSize = value; }
}
/// <summary>
/// 验证码类型
/// </summary>
public CaptchaType CaptchaType
{
get { return _captchaType; }
set { _captchaType = value; }
}
#endregion
#region Public Methods
/// <summary>
/// 获取生成的验证码图片
/// </summary>
/// <param name="matchCode">与验证码图片相匹配的内容,一般将该内容保存至session中,用于校验</param>
/// <returns>验证码图片</returns>
public Bitmap GetCaptchaPic(out string matchCode)
{
matchCode = null;
string captchaContent = null;
switch (_captchaType) //需要生成的验证码类型
{
case CaptchaType.RandomString:
{
string randomStr = CreateCheckCodeString(4);
captchaContent = randomStr;
matchCode = randomStr;
break;
}
case CaptchaType.RandomOperationExpression:
{
string[] codes = CreateOperateCheckCode();
captchaContent = codes[0];
matchCode = codes[1];
break;
}
case CaptchaType.RandomType:
{
RandomSelectCreateMethod(out captchaContent, out matchCode);
break;
}
default:
throw new Exception("unknow CaptchaType!");
}
return GenerateCaptchaPic(captchaContent); //生成验证码图片
}
#endregion
#region Private Methods
/// <summary>
/// 生成验证码图片
/// </summary>
/// <param name="captchaContent">验证码内容</param>
/// <returns>图片</returns>
private Bitmap GenerateCaptchaPic(string captchaContent)
{
var font = new Font("Arial", _fontSize, FontStyle.Bold);//验证码字体
var brush = new SolidBrush(Color.Black);//用于写验证码的画笔
var crosswise = new Pen(Color.Green, 0);//画横向干扰线的钢笔
var vertical = new Pen(Color.FromArgb(255, 100, 100, 100), 0);//画纵向干扰线的钢笔
var image = new Bitmap(_width, _height);//生成图像
using (Graphics g = Graphics.FromImage(image)) //生成一个绘画面板（画布）
{
g.Clear(ColorTranslator.FromHtml("#f0f0f0"));//用指定颜色填充画布
RectangleF rect = new RectangleF(5, 2, _width, _height);//定义文字的绘制矩形
Random rand = new Random((int)DateTime.Now.Ticks);//生成干扰线的随机对象
for (int i = 1; i <= 4; i++) //干扰线
{
Point start = new Point(0, rand.Next(_height));
Point end = new Point(_width, rand.Next(_height));
g.DrawLine(crosswise, start, end);
}
for (int i = 1; i <= 5; i++) //干扰线
{
Point start = new Point(rand.Next(_width), 0);
Point end = new Point(rand.Next(_width), _height);
g.DrawLine(vertical, start, end);
}
g.DrawString(captchaContent, font, brush, rect);//将验证码写到画布上
}
return image;
}
/// <summary>
/// 随机选择生成验证码的方法
/// </summary>
/// <param name="captchaContent">验证码图片显示的内容</param>
/// <param name="matchCode">与验证码图片匹配的内容</param>
private void RandomSelectCreateMethod(out string captchaContent, out string matchCode)
{
captchaContent = "";
matchCode = "";
int currSeconds = DateTime.Now.Second;
if (currSeconds % 2 == 0)
{
captchaContent = matchCode = CreateCheckCodeString(4);
}
else
{
string[] codes = CreateOperateCheckCode();
captchaContent = codes[0];
matchCode = codes[1];
}
return;
}
/// <summary>
/// 生成len位随机字符串
/// </summary>
/// <param name="len">随机字符串长度</param>
/// <returns>len位随机字符串</returns>
private string CreateCheckCodeString(int len)
{
//定义用于验证码的字符数组
char[] checkCodeArray ={ '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'};
//定义验证码字符串
string randomcode = "";
Random rd = new Random();
//生成4位验证码字符串
for (int i = 1; i <= len; i++)
randomcode += checkCodeArray[rd.Next(checkCodeArray.Length)];
return randomcode;
}
/// <summary>
/// 生成随机的运算表达式 1+1=?,2
/// </summary>
/// <returns>codes[0]: 表达式; codes[1]: 运算结果</returns>
private string[] CreateOperateCheckCode()
{
string[] codes = new string[2] { "", "" };
string[] operators = new string[] { "+", "-" };
int result = 0;
Random random = new Random();
int num1 = random.Next(10); // [0,19)
int num2 = random.Next(10);
string oper = operators[random.Next(operators.Length)];
switch (oper)
{
case "+":
{
result = num1 + num2;
break;
}
case "-":
{
result = num1 - num2;
break;
}
default:
throw new Exception("operators error");
}
codes[0] = string.Format("{0}{1}{2}=?", num1, oper, num2);
codes[1] = result.ToString();
return codes;
}
#endregion
}
/// <summary>
/// 生成的验证码类型
/// </summary>
public enum CaptchaType
{
/// <summary>
/// 随机类型, 在所有支持的验证码类型中,随机选择一种
/// </summary>
RandomType,
/// <summary>
/// 普通的随机字符串,如: jH9Y, 12H8
/// </summary>
RandomString,
/// <summary>
/// 随机运算表达式, 如: 1+2=?, 5加2=?, 4-2=?
/// </summary>
RandomOperationExpression,
}
一般处理程序(.ashx)示例:
/// <summary>
/// 生成图形验证码
/// </summary>
public class CreateCode : IHttpHandler, IRequiresSessionState
{
private static readonly string CodeSessionName = "Code_Session_Name";
public void ProcessRequest(HttpContext context)
{
string checkCodeSession = string.Empty;
var captChaPic = new PicCaptcha();
using (var image = captChaPic.GetCaptchaPic(out checkCodeSession)) //获取验证码图片
using (var ms = new MemoryStream())
{
context.Session.Add(CodeSessionName, checkCodeSession); //验证码校验内容保存到sessioin中
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
context.Response.ClearContent();
context.Response.ContentType = "image/Gif";
context.Response.BinaryWrite(ms.ToArray());
}
return;
}
public bool IsReusable
{
get
{
return false;
}
}
}
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