12306奇葩验证码引发思考之C#实现验证码程序

近日铁路订票网“12306”又出现多道另类考题，竟要订票者在8个图案中“点击图中所有美男子”、“请点击下图中所有的非智能眼镜”、“请点击下图中所有的博斯普鲁斯海峡”，网友吐槽：比高考题还难，到底是什么样子的，先跟大家分享一下几个例子：

哈哈，是有点奇葩的验证码，怪不得有人会说“妈妈我已经找不到回家”，这让分秒必争的春运网上抢票者瞬间傻眼，九成网友已经被打败……

正巧小编最近也在研究验证码，参考了许多网上案例，整理了一篇文章特分享给大家。

验证码的一般编写思路为：
       1.定义验证码字符长度;
       2.根据长度随机生成验证码字符串;
       3.将验证码字符串转换成图片形式，并在图片中生成随机噪声点和声线（对验证码进行模糊识别处理）;
       4.显示结果。

 ///
 /// 生成随机验证码
 ///
 /// 验证码长度
 ///
 public string createidentifyingcode(int codelen)
 {
 if (codelen < 1)
  return string.empty;
 int num;
 string checkcode = string.empty;
 random random = new random();
 for (int index = 0; index < codelen; index++)
 {
  num = random.next();
  if (num % 2 == 0)
  checkcode += (char)('0' + (char)(num % 10));
  else
  checkcode += (char)('a' + (char)(num % 26));
 }
 return checkcode;
 }
-------------------------------------------------------------------------------------------------
 ///
 /// 生成验证码图片
 ///
 ///
 /// 
 private void createcheckcodeimage(string checkcode)
 {
  if (checkcode == null || checkcode.trim() == string.empty)
  return;
  //创建图片大小
  system.drawing.bitmap image = new  system.drawing.bitmap((int)math.ceiling(checkcode.length*12.5),22);
  //创建画板
  graphics graphic = graphics.fromimage(image);
 
  try
  {
  random random = new random();
  graphic.clear(color.white);
  int x1 = 0, y1 = 0, x2 = 0, y2 = 0;
  //画图片背景噪声线
  for (int index = 0; index < 25; index++)
  {
   x1 = random.next(image.width);
   y1 = random.next(image.height);
   x2 = random.next(image.width);
   y2 = random.next(image.height);
   graphic.drawline(new pen(color.silver),x1,y1,x2,y2);
  }
  font font = new system.drawing.font("helvetica", 12, (fontstyle.bold |fontstyle.italic));
  lineargradientbrush brush = new lineargradientbrush(new rectangle(0, 0, image.width, image.height),color.blue,color.darkblue,1.2f,true);
  graphic.drawstring(checkcode,font,brush,2,2);
 
  int x = 0;
  int y = 0;
  // 画图片的前景噪声点
  for (int index = 0; index < 100; index++)
  {
   x = random.next(image.width);
   y = random.next(image.height);
   image.setpixel(x,y,color.fromargb(random.next()));
  }
  //画图片的边框线
  graphic.drawrectangle(new pen(color.silver), 0, 0, image.width - 1, image.height - 1);
  //网页响应
  system.io.memorystream ms = new system.io.memorystream();
  image.save(ms,system.drawing.imaging.imageformat.gif);
  response.clearcontent();
  response.contenttype = "image/gif";
  response.binarywrite(ms.toarray());
  }
  finally
  {
  graphic.dispose();
  image.dispose();
  }
 }

以上所生成的为简单的验证码。接下来我从其他的博客中学习了其他形式的效果。

/* 图片画线特殊效果：贝塞尔曲线 */
  graphics graph = graphics.fromimage(image);
  graph.clear(color.whitesmoke);
  point[] myarray ={
     new point(random.next(150),random.next(50)),
     new point(random.next(150),random.next(50)),
     new point(random.next(150),random.next(50)),
     new point(random.next(150),random.next(50)),
     new point(random.next(150),random.next(50)),
     new point(random.next(150),random.next(50)),
     new point(random.next(150),random.next(50)),
     new point(random.next(150),random.next(50)),
     new point(random.next(150),random.next(50)),
     new point(random.next(150),random.next(50))
    };
  pen mypen = new pen(color.blue, 1);
  graphicspath mypath = new graphicspath();
  mypath.addbeziers(myarray);
  graph.drawpath(mypen, mypath);

验证码字符颜色变换效果：实现该效果，我们首先来定义一个颜色集合，然后通过for循环使其随机改变字体颜色则可。

 #region 定义颜色数组
 color[] colors = { color.blue, color.green, color.red, color.gold, color.black, color.chocolate, color.orange, color.purple };
 public color[] colors
 {
  get { return colors; }
  set { colors = value; }
 }
 #endregion
 brush brush;
 int colornum;
 for(int i=0; i
 {
  colornum = random.next(colors.length - 1);
  brush = new system.drawing.solidbrush(colors[cindex]);
 
  //利用drawstring函数进行颜色填充就可以了。
 }

 同样的原理我们也可以定义一个字体的数组来进行验证码字体切换。代码和颜色的类似，这里就不加以累赘。
接下来看看如何使得验证码的字体进行扭曲。

private const double pi = 3.1415926535897932384626433832795;
 private const double pi2 = 6.283185307179586476925286766559;
 ///
 /// 波形滤镜效果函数
 ///
 ///
 ///
 ///
 ///
 ///
 public system.drawing.bitmap twistimage(bitmap srcbmp, double dmultvalue, double dphase)
 {
  system.drawing.bitmap destbmp = new bitmap(srcbmp.width,srcbmp.height);
  system.drawing.graphics graph = system.drawing.graphics.fromimage(destbmp);
  //填充背景图为白色
  graph.fillrectangle(new solidbrush(system.drawing.color.white), 0, 0, destbmp.width, destbmp.height);
  graph.dispose();
  double dbaselen = (double)destbmp.width;
  for (int i = 0; i < destbmp.width; i++)
  {
  for (int j = 0; j < destbmp.height; j++)
  {
   double dx = 0;
   dx = (pi2 * (double)j) / dbaselen;
   dx += dphase;
 
   double dy = math.sin(dx);
 
   int noldx = 0, noldy = 0;
   noldx = i + (int)(dy * dmultvalue);
   noldy = j + (int)(dy * dmultvalue);
   system.drawing.color color = srcbmp.getpixel(i, j);
   if (noldx >= 0 && noldx < destbmp.width && noldy >= 0 && noldy < destbmp.height)
   destbmp.setpixel(noldx, noldy, color);
  }
  }
  return destbmp;
 }

上面代码是参考了这段代码进行的学习<c#.net 好用的验证码代码 汉字-变色-扭曲-波动 >，代码如下

using system;
using system.data;
using system.configuration;
using system.collections;
using system.drawing;
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;

public partial class study_checkcode2 : system.web.ui.page
{
 protected void page_load(object sender, eventargs e)
 {
 string code = createverifycode();  //取随机码
 createimageonpage(code, this.context); // 输出图片
 response.cookies.add(new httpcookie("checkcode", code.toupper()));// 使用cookies取验证码的值
 }

 #region 验证码长度(默认4个验证码的长度)
 int length = 4;
 public int length
 {
 get { return length; }
 set { length = value; }
 }
 #endregion

 #region 验证码字体大小(为了显示扭曲效果，默认40像素，可以自行修改)
 int fontsize = 40;
 public int fontsize
 {
 get { return fontsize; }
 set { fontsize = value; }
 }
 #endregion

 #region 边框补(默认1像素)
 int padding = 2;
 public int padding
 {
 get { return padding; }
 set { padding = value; }
 }
 #endregion

 #region 是否输出燥点(默认不输出)
 bool chaos = true;
 public bool chaos
 {
 get { return chaos; }
 set { chaos = value; }
 }
 #endregion

 #region 输出燥点的颜色(默认灰色)
 color chaoscolor = color.lightgray;
 public color chaoscolor
 {
 get { return chaoscolor; }
 set { chaoscolor = value; }
 }
 #endregion

 #region 自定义背景色(默认白色)
 color backgroundcolor = color.white;
 public color backgroundcolor
 {
 get { return backgroundcolor; }
 set { backgroundcolor = value; }
 }
 #endregion

 #region 自定义随机颜色数组
 color[] colors = { color.black, color.red, color.darkblue, color.green, color.orange, color.brown, color.darkcyan, color.purple };
 public color[] colors
 {
 get { return colors; }
 set { colors = value; }
 }
 #endregion

 #region 自定义字体数组
 string[] fonts = { "arial", "georgia" };
 public string[] fonts
 {
 get { return fonts; }
 set { fonts = value; }
 }
 #endregion

 #region 自定义随机码字符串序列(使用逗号分隔)
 //string codeserial = "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,v,w,x,y,z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z";
 string codeserial = "阿,保,持,的,法,规,和,东,三,省,问,我,惹,你,诶,没,改,变,揍,屁,股,吧";
 public string codeserial
 {
 get { return codeserial; }
 set { codeserial = value; }
 }
 #endregion

 #region 产生波形滤镜效果

 private const double pi = 3.1415926535897932384626433832795;
 private const double pi2 = 6.283185307179586476925286766559;

 /// <summary>
 /// 正弦曲线wave扭曲图片（edit by 51aspx.com）
 /// </summary>
 /// <param name="srcbmp">图片路径</param>
 /// <param name="bxdir">如果扭曲则选择为true</param>
 /// <param name="dmultvalue">波形的幅度倍数，越大扭曲的程度越高，一般为3</param>
 /// <param name="dphase">波形的起始相位，取值区间[0-2*pi)</param>
 /// <returns></returns>
 public system.drawing.bitmap twistimage(bitmap srcbmp, bool bxdir, double dmultvalue, double dphase)
 {
 system.drawing.bitmap destbmp = new bitmap(srcbmp.width, srcbmp.height);

 // 将位图背景填充为白色
 system.drawing.graphics graph = system.drawing.graphics.fromimage(destbmp);
 graph.fillrectangle(new solidbrush(system.drawing.color.white), 0, 0, destbmp.width, destbmp.height);
 graph.dispose();

 double dbaseaxislen = bxdir ? (double)destbmp.height : (double)destbmp.width;

 for (int i = 0; i < destbmp.width; i++)
 {
  for (int j = 0; j < destbmp.height; j++)
  {
  double dx = 0;
  dx = bxdir ? (pi2 * (double)j) / dbaseaxislen : (pi2 * (double)i) / dbaseaxislen;
  dx += dphase;
  double dy = math.sin(dx);

  // 取得当前点的颜色
  int noldx = 0, noldy = 0;
  noldx = bxdir ? i + (int)(dy * dmultvalue) : i;
  noldy = bxdir ? j : j + (int)(dy * dmultvalue);

  system.drawing.color color = srcbmp.getpixel(i, j);
  if (noldx >= 0 && noldx < destbmp.width
   && noldy >= 0 && noldy < destbmp.height)
  {
   destbmp.setpixel(noldx, noldy, color);
  }
  }
 }
 return destbmp;
 }
 #endregion

 #region 生成校验码图片
 public bitmap createimagecode(string code)
 {
 int fsize = fontsize;
 int fwidth = fsize + padding;

 int imagewidth = (int)(code.length * fwidth) + 30 + padding * 2;
 int imageheight = fsize * 2 + padding;

 system.drawing.bitmap image = new system.drawing.bitmap(imagewidth, imageheight);

 graphics g = graphics.fromimage(image);

 g.clear(backgroundcolor);

 random rand = new random();

 //给背景添加随机生成的燥点
 if (this.chaos)
 {

  pen pen = new pen(chaoscolor, 0);
  int c = length * 10;

  for (int i = 0; i < c; i++)
  {
  int x = rand.next(image.width);
  int y = rand.next(image.height);

  g.drawrectangle(pen, x, y, 1, 1);
  }
 }

 int left = 0, top = 0, top1 = 1, top2 = 1;

 int n1 = (imageheight - fontsize - padding * 2);
 int n2 = n1 / 4;
 top1 = n2;
 top2 = n2 * 2;

 font f;
 brush b;

 int cindex, findex;

 //随机字体和颜色的验证码字符
 for (int i = 0; i < code.length; i++)
 {
  cindex = rand.next(colors.length - 1);
  findex = rand.next(fonts.length - 1);

  f = new system.drawing.font(fonts[findex], fsize, system.drawing.fontstyle.bold);
  b = new system.drawing.solidbrush(colors[cindex]);

  if (i % 2 == 1)
  {
  top = top2;
  }
  else
  {
  top = top1;
  }

  left = i * fwidth;

  g.drawstring(code.substring(i, 1), f, b, left, top);
 }

 //画一个边框 边框颜色为color.gainsboro
 g.drawrectangle(new pen(color.gainsboro, 0), 0, 0, image.width - 1, image.height - 1);
 g.dispose();

 //产生波形（add by 51aspx.com）
 image = twistimage(image, true, 8, 4);

 return image;
 }
 #endregion

 #region 将创建好的图片输出到页面
 public void createimageonpage(string code, httpcontext context)
 {
 system.io.memorystream ms = new system.io.memorystream();
 bitmap image = this.createimagecode(code);

 image.save(ms, system.drawing.imaging.imageformat.jpeg);

 context.response.clearcontent();
 context.response.contenttype = "image/jpeg";
 context.response.binarywrite(ms.getbuffer());

 ms.close();
 ms = null;
 image.dispose();
 image = null;
 }
 #endregion

 #region 生成随机字符码
 public string createverifycode(int codelen)
 {
 if (codelen == 0)
 {
  codelen = length;
 }

 string[] arr = codeserial.split(',');

 string code = "";

 int randvalue = -1;

 random rand = new random(unchecked((int)datetime.now.ticks));

 for (int i = 0; i < codelen; i++)
 {
  randvalue = rand.next(0, arr.length - 1);

  code += arr[randvalue];
 }

 return code;
 }
 public string createverifycode()
 {
 return createverifycode(0);
 }
 #endregion

}

一年一度的抢票热潮又开始了，希望大家都能顺利买到回家的火车篇，回家过年，突然感觉有点年味了，一年又一年，时间都去哪了，小小的感慨一下……

言归正传，这就是为大家分享的c#验证码程序，和12306验证码差多了，不过也是小编的学习收获吧！大家也可以结合下面这两篇文章进行学习：

《12306动态验证码启发之asp.net实现动态gif验证码(附源码)》

希望本文所述对大家学习验证码技术有所帮助。