由12306动态验证码想到的ASP.NET实现动态GIF验证码(附源码)

景：

12306网站推出“彩色动态验证码机制”，新版验证码不但经常出现字符叠压，还不停抖动，不少人大呼“看不清”，称“那个验证码，是毕加索的抽象画么!”铁总客服则表示:为了能正常购票只能这样。而多家抢票软件接近“报废”，引发不少网友不满的吐槽称“太抽象太艺术了”。

正题：

以前做项目有时候也会用到验证码，但基本都是静态的。这次也想凑凑12306的热闹。

闲言少续，切入正题，先上代码，实现方法：

public void ShowCode()
{
//对象实例化
Validate GifValidate = new Validate();
#region 对验证码进行设置(不进行设置时,将以默认值生成)
//验证码位数，不小于4位
GifValidate.ValidateCodeCount = 4;
//验证码字体型号(默认13)
GifValidate.ValidateCodeSize = 13;
//验证码图片高度,高度越大,字符的上下偏移量就越明显
GifValidate.ImageHeight = 23;
//验证码字符及线条颜色(需要参考颜色类)
GifValidate.DrawColor = System.Drawing.Color.BlueViolet;
//验证码字体(需要填写服务器安装的字体)
GifValidate.ValidateCodeFont = "Arial";
//验证码字符是否消除锯齿
GifValidate.FontTextRenderingHint = false;
//定义验证码中所有的字符(","分离),似乎暂时不支持中文
GifValidate.AllChar = "1,2,3,4,5,6,7,8,9,0,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";
#endregion
//输出图像(Session名称)
GifValidate.OutPutValidate("GetCode");
}

调用主要方法：

public class Validate
{
public string AllChar = "1,2,3,4,5,6,7,8,9,0,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";
public Color DrawColor = Color.BlueViolet;
public bool FontTextRenderingHint = false;
public int ImageHeight = 0x17;
private byte TrueValidateCodeCount = 4;
protected string ValidateCode = "";
public string ValidateCodeFont = "Arial";
public float ValidateCodeSize = 13f;
private void CreateImageBmp(out Bitmap ImageFrame)
{
char[] chArray = this.ValidateCode.ToCharArray(0, this.ValidateCodeCount);
int width = (int) (((this.TrueValidateCodeCount * this.ValidateCodeSize) * 1.3) + 4.0);
ImageFrame = new Bitmap(width, this.ImageHeight);
Graphics graphics = Graphics.FromImage(ImageFrame);
graphics.Clear(Color.White);
Font font = new Font(this.ValidateCodeFont, this.ValidateCodeSize, FontStyle.Bold);
Brush brush = new SolidBrush(this.DrawColor);
int maxValue = (int) Math.Max((float) ((this.ImageHeight - this.ValidateCodeSize) - 3f), (float) 2f);
Random random = new Random();
for (int i = 0; i < this.TrueValidateCodeCount; i++)
{
int[] numArray = new int[] { (((int) (i * this.ValidateCodeSize)) + random.Next(1)) + 3, random.Next(maxValue) };
Point point = new Point(numArray[0], numArray[1]);
if (this.FontTextRenderingHint)
{
graphics.TextRenderingHint = TextRenderingHint.SingleBitPerPixel;
}
else
{
graphics.TextRenderingHint = TextRenderingHint.AntiAlias;
}
graphics.DrawString(chArray[i].ToString(), font, brush, (PointF) point);
}
graphics.Dispose();
}
private void CreateImageGif()
{
AnimatedGifEncoder encoder = new AnimatedGifEncoder();
MemoryStream stream = new MemoryStream();
encoder.Start();
encoder.SetDelay(5);
encoder.SetRepeat(0);
for (int i = 0; i < 10; i++)
{
Bitmap bitmap;
this.CreateImageBmp(out bitmap);
this.DisposeImageBmp(ref bitmap);
bitmap.Save(stream, ImageFormat.Png);
encoder.AddFrame(Image.FromStream(stream));
stream = new MemoryStream();
}
encoder.OutPut(ref stream);
HttpContext.Current.Response.ClearContent();
HttpContext.Current.Response.ContentType = "p_w_picpath/Gif";
HttpContext.Current.Response.BinaryWrite(stream.ToArray());
stream.Close();
stream.Dispose();
}
private void CreateValidate()
{
this.ValidateCode = "";
string[] strArray = this.AllChar.Split(new char[] { ',' });
int index = -1;
Random random = new Random();
for (int i = 0; i < this.ValidateCodeCount; i++)
{
if (index != -1)
{
random = new Random((i * index) * ((int) DateTime.Now.Ticks));
}
int num3 = random.Next(0x23);
if (index == num3)
{
this.CreateValidate();
}
index = num3;
this.ValidateCode = this.ValidateCode + strArray[index];
}
if (this.ValidateCode.Length > this.TrueValidateCodeCount)
{
this.ValidateCode = this.ValidateCode.Remove(this.TrueValidateCodeCount);
}
}
private void DisposeImageBmp(ref Bitmap ImageFrame)
{
Graphics graphics = Graphics.FromImage(ImageFrame);
Pen pen = new Pen(this.DrawColor, 1f);
Random random = new Random();
Point[] pointArray = new Point[2];
for (int i = 0; i < 15; i++)
{
pointArray[0] = new Point(random.Next(ImageFrame.Width), random.Next(ImageFrame.Height));
pointArray[1] = new Point(random.Next(ImageFrame.Width), random.Next(ImageFrame.Height));
graphics.DrawLine(pen, pointArray[0], pointArray[1]);
}
graphics.Dispose();
}
public void OutPutValidate(string ValidateCodeSession)
{
this.CreateValidate();
this.CreateImageGif();
HttpContext.Current.Session[ValidateCodeSession] = this.ValidateCode;
}
public byte ValidateCodeCount
{
get
{
return this.TrueValidateCodeCount;
}
set
{
if (value > 4)
{
this.TrueValidateCodeCount = value;
}
}
}
}

验证码效果：

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