C#实现的一款比较美观的验证码完整实例

本文实例讲述了c#实现的一款比较美观的验证码。分享给大家供大家参考，具体如下：

using system;
using system.collections.generic;
using system.web;
using system.web.ui;
using system.web.ui.webcontrols;
using system.drawing;
using system.io;
using system.drawing.imaging;
public partial class validatecode : system.web.ui.page
{
 private int letterwidth = 16;//单个字体的宽度范围
 private int letterheight = 22;//单个字体的高度范围
 private int lettercount = 4;//验证码位数
 private char[] chars = "0123456789".tochararray();
 private string[] fonts = { "arial", "georgia" };
 /// <summary>
 /// 产生波形滤镜效果
 /// </summary>
 private const double pi = 3.1415926535897932384626433832795;
 private const double pi2 = 6.283185307179586476925286766559;
 protected void page_load(object sender, eventargs e)
 {
  //防止网页后退--禁止缓存
  response.expires = 0;
  response.buffer = true;
  response.expiresabsolute = datetime.now.addseconds(-1);
  response.addheader("pragma", "no-cache");
  response.cachecontrol = "no-cache";
  string str_validatecode = getrandomnumberstring(lettercount);
  httpcookie objcookie = new httpcookie("validatecode");
  objcookie.value = str_validatecode;
  objcookie.path = "/";
  objcookie.expires = datetime.now.addseconds(1200);
  response.cookies.add(objcookie);
  createimage(str_validatecode);
 }
 public void createimage(string checkcode)
 {
  int int_imagewidth = checkcode.length * letterwidth;
  random newrandom = new random();
  bitmap image = new bitmap(int_imagewidth, letterheight);
  graphics g = graphics.fromimage(image);
  //生成随机生成器
  random random = new random();
  //白色背景
  g.clear(color.white);
  //画图片的背景噪音线
  for (int i = 0; i < 10; 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);
  }
  //画图片的前景噪音点
  for (int i = 0; i < 10; i++)
  {
   int x = random.next(image.width);
   int y = random.next(image.height);
   image.setpixel(x, y, color.fromargb(random.next()));
  }
  //随机字体和颜色的验证码字符
  int findex;
  for (int int_index = 0; int_index < checkcode.length; int_index++)
  {
   findex = newrandom.next(fonts.length - 1);
   string str_char = checkcode.substring(int_index, 1);
   brush newbrush = new solidbrush(getrandomcolor());
   point thepos = new point(int_index * letterwidth + 1 + newrandom.next(3), 1 + newrandom.next(3));//5+1+a+s+p+x
   g.drawstring(str_char, new font(fonts[findex], 12, fontstyle.bold), newbrush, thepos);
  }
  //灰色边框
  g.drawrectangle(new pen(color.lightgray, 1), 0, 0, int_imagewidth - 1, (letterheight - 1));
  //图片扭曲
  //image = twistimage(image, true, 3, 4);
  //将生成的图片发回客户端
  memorystream ms = new memorystream();
  image.save(ms, imageformat.png);
  response.clearcontent(); //需要输出图象信息 要修改http头
  response.contenttype = "image/png";
  response.binarywrite(ms.toarray());
  g.dispose();
  image.dispose();
 }
 /// <summary>
 /// 正弦曲线wave扭曲图片
 /// </summary>
 /// <param name="srcbmp">图片路径</param>
 /// <param name="bxdir">如果扭曲则选择为true</param>
 /// <param name="nmultvalue">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;
 }
 public color getrandomcolor()
 {
  random randomnum_first = new random((int)datetime.now.ticks);
  system.threading.thread.sleep(randomnum_first.next(50));
  random randomnum_sencond = new random((int)datetime.now.ticks);
  int int_red = randomnum_first.next(210);
  int int_green = randomnum_sencond.next(180);
  int int_blue = (int_red + int_green > 300) ? 0 : 400 - int_red - int_green;
  int_blue = (int_blue > 255) ? 255 : int_blue;
  return color.fromargb(int_red, int_green, int_blue);// 5+1+a+s+p+x
 }
 // 生成随机数字字符串
 public string getrandomnumberstring(int int_numberlength)
 {
  random random = new random();
  string validatecode = string.empty;
  for (int i = 0; i < int_numberlength; i++)
   validatecode += chars[random.next(0, chars.length)].tostring();
  return validatecode;
 }
}

<img alt="看不清，换一张" title="看不清，换一张" src="validatecode.aspx" style="cursor:pointer" onclick="this.src=this.src+'?r='+math.random()" />

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