一个简单的ASP.NET验证码

本文实例为大家分享了asp.net验证码的具体代码，供大家参考，具体内容如下

我主要是看到干扰线了，一个验证码里面要是没有干扰线什么的，至少得在噪点和随机码的排版上下工夫：

 /// <summary>
 /// 验证码生成类
 /// </summary>
 public class verify_code : ihttphandler, irequiressessionstate
 {
  public void processrequest(httpcontext context)
  {
   int codew = 80;
   int codeh = 22;
   int fontsize = 16;
   string chkcode = string.empty;
   //颜色列表，用于验证码、噪线、噪点 
   color[] color = { color.black, color.red, color.blue, color.green, color.orange, color.brown, color.brown, color.darkblue };
   //字体列表，用于验证码 
   string[] font = { "times new roman", "verdana", "arial", "gungsuh", "impact" };
   //验证码的字符集，去掉了一些容易混淆的字符 
   char[] character = { '0', '1', '2', '3', '4', '5', '6', '8', '9' };
   random rnd = new random();
   //生成验证码字符串 
   for (int i = 0; i < 4; i++)
   {
    chkcode += character[rnd.next(character.length)];
   }
   //写入session
   context.session["sys_verify_code"] = chkcode;
   //创建画布
   bitmap bmp = new bitmap(codew, codeh);
   graphics g = graphics.fromimage(bmp);
   g.clear(color.white);
   //画噪线 
   for (int i = 0; i < 4; i++)
   {
    int x1 = rnd.next(codew);
    int y1 = rnd.next(codeh);
    int x2 = rnd.next(codew);
    int y2 = rnd.next(codeh);
    color clr = color[rnd.next(color.length)];
    g.drawline(new pen(clr), x1, y1, x2, y2);
   }
   //画验证码字符串 
   for (int i = 0; i < chkcode.length; i++)
   {
    string fnt = font[rnd.next(font.length)];
    font ft = new font(fnt, fontsize);
    color clr = color[rnd.next(color.length)];
    g.drawstring(chkcode[i].tostring(), ft, new solidbrush(clr), (float)i * 18 + 2, (float)0);
   }
   //画噪点 
   for (int i = 0; i < 100; i++)
   {
    int x = rnd.next(bmp.width);
    int y = rnd.next(bmp.height);
    color clr = color[rnd.next(color.length)];
    bmp.setpixel(x, y, clr);
   }
   //清除该页输出缓存，设置该页无缓存 
   context.response.buffer = true;
   context.response.expiresabsolute = system.datetime.now.addmilliseconds(0);
   context.response.expires = 0;
   context.response.cachecontrol = "no-cache";
   context.response.appendheader("pragma", "no-cache");
   //将验证码图片写入内存流，并将其以 "image/png" 格式输出 
   memorystream ms = new memorystream();
   try
   {
    bmp.save(ms, imageformat.png);
    context.response.clearcontent();
    context.response.contenttype = "image/png";
    context.response.binarywrite(ms.toarray());
   }
   finally
   {
    //显式释放资源 
    bmp.dispose();
    g.dispose();
   }
  }

  public bool isreusable
  {
   get
   {
    return false;
   }
  }
 }

基本验证生成代码demo：

using system;
using system.drawing;
using system.drawing.imaging;
using system.io;
using system.web;

public partial class image : system.web.ui.page
{
 protected void page_load(object sender, eventargs e)
 {
  string tmp = rndnum(4);
  httpcookie a = new httpcookie("imagev", tmp);
  response.cookies.add(a);
  this.validatecode(tmp);
 }

 private void validatecode(string vnum)
 {
  bitmap img = null;
  graphics g = null;
  memorystream ms = null;
  int gheight = vnum.length * 12;
  img = new bitmap(gheight, 25);
  g = graphics.fromimage(img);
  //背景颜色
  g.clear(color.white);
  //文字字体
  font f = new font("arial black", 10);
  //文字颜色
  solidbrush s = new solidbrush(color.black);
  g.drawstring(vnum, f, s, 3, 3);
  ms = new memorystream();
  img.save(ms, imageformat.jpeg);
  response.clearcontent();
  response.contenttype = "image/jpeg";
  response.binarywrite(ms.toarray());

  g.dispose();
  img.dispose();
  response.end();
 }

 private string rndnum(int vcodenum)
 {
  string vchar = "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";
  string[] vcarray = vchar.split(new char[] { ',' });
  string vnum = "";
  int temp = -1;

  random rand = new random();

  for (int i = 1; i < vcodenum + 1; i++)
  {
   if (temp != -1)
   {
    rand = new random(i * temp * unchecked((int)datetime.now.ticks));
   }

   int t = rand.next(35);
   if (temp != -1 && temp == t)
   {
    return rndnum(vcodenum);
   }
   temp = t;
   vnum += vcarray[t];
  }
  return vnum;
 }

}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。