理解C#生成验证码的过程

本文实例为大家介绍了生成验证码的详细过程，供大家参考，具体内容如下

生成验证码的类：

using system;
using system.collections.generic;
using system.drawing;
using system.text;

namespace controllers.core.util
{
  /// <summary>
  /// 验证码
  /// </summary>
  public class verifycodehelper : adminbasecontroller
  {
    #region 变量
    /// <summary>
    /// 颜色表
    /// </summary>
    private static color[] colors = new color[]{
      color.fromargb(220,20,60),
      color.fromargb(128,0,128),
      color.fromargb(65,105,225),
      color.fromargb(70,130,180),
      color.fromargb(46,139,87),
      color.fromargb(184,134,11),
      color.fromargb(255,140,0),
      color.fromargb(139,69,19),
      color.fromargb(0,191,255),
      color.fromargb(95,158,160),
      color.fromargb(255,20,147),
      color.fromargb(255,165,0)};

    /// <summary>
    /// 字体表
    /// </summary>
    private static string[] fonts = new string[] { 
      "arial",
      "verdana", 
      "georgia", 
      "黑体" };

    /// <summary>
    /// 字体大小
    /// </summary>
    private static int fontsize = 22;
    #endregion

    #region 生成验证码图片
    /// <summary>
    /// 生成验证码图片
    /// </summary>
    public static bitmap createverifycodebmp(out string code)
    {
      int width = 120;
      int height = 40;
      bitmap bmp = new bitmap(width, height);
      graphics g = graphics.fromimage(bmp);
      random rnd = new random();

      //背景色
      g.fillrectangle(new solidbrush(color.white), new rectangle(0, 0, width, height));

      //文字
      stringbuilder sbcode = new stringbuilder();
      for (int i = 0; i < 4; i++)
      {
        string str = getchar(rnd);
        font font = getfont(rnd);
        color color = getcolor(rnd);
        g.drawstring(str, font, new solidbrush(color), new pointf((float)(i * width / 4.0), 0));
        sbcode.append(str);
      }
      code = sbcode.tostring();

      //噪音线
      for (int i = 0; i < 10; i++)
      {
        int x1 = rnd.next(bmp.width);
        int x2 = rnd.next(bmp.width);
        int y1 = rnd.next(bmp.height);
        int y2 = rnd.next(bmp.height);

        pen p = new pen(getcolor(rnd), 1);
        g.drawline(p, x1, y1, x2, y2);
      }

      //扭曲
      bmp = twistimage(bmp, true, 3, rnd.nextdouble() * math.pi * 2);
      g = graphics.fromimage(bmp);

      //噪点
      for (int i = 0; i < 100; i++)
      {
        int x1 = rnd.next(bmp.width);
        int y1 = rnd.next(bmp.height);

        pen p = new pen(getcolor(rnd), 1);
        g.drawrectangle(p, x1, y1, 1, 1);
      }

      //边框
      g.drawrectangle(new pen(new solidbrush(color.fromargb(153, 153, 153))), new rectangle(0, 0, width - 1, height - 1));

      return bmp;
    }
    #endregion

    #region 获取随机字符
    /// <summary>
    /// 获取随机字符
    /// </summary>
    private static string getchar(random rnd)
    {
      int n = rnd.next(0, 61);
      if (n <= 9)
      {
        return ((char)(48 + n)).tostring();
      }
      else if (n <= 35)
      {
        return ((char)(65 + n - 10)).tostring();
      }
      else
      {
        return ((char)(97 + n - 36)).tostring();
      }
    }
    #endregion

    #region 获取随机字体
    /// <summary>
    /// 获取随机字体
    /// </summary>
    private static font getfont(random rnd)
    {
      return new font(fonts[rnd.next(0, fonts.length)], fontsize, fontstyle.bold);
    }
    #endregion

    #region 获取随机颜色
    /// <summary>
    /// 获取随机颜色
    /// </summary>
    private static color getcolor(random rnd)
    {
      return colors[rnd.next(0, colors.length)];
    }
    #endregion

    #region 正弦曲线wave扭曲图片
    /// <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="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>  
    private static 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 ? (math.pi * 2 * (double)j) / dbaseaxislen : (math.pi * 2 * (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

  }
}

验证码页面action：

public actionresult verifycode()
{
  string code;
  bitmap bmp = verifycodehelper.createverifycodebmp(out code);
  bitmap newbmp = new bitmap(bmp, 108, 36);
  httpcontext.session["verifycode"] = code;

  response.clear();
  response.contenttype = "image/bmp";
  newbmp.save(response.outputstream, system.drawing.imaging.imageformat.bmp);

  return view();
}

说明：前台页面为空的cshtml页面，验证码的值放在session中。

使用验证码的页面：

显示验证码的img：

<img id="verifycode" src="" alt="验证码" style="vertical-align: middle;" />
页面加载完成后，显示验证码(注意，要加上时间戳，不然刷新页面时验证码不刷新)：

$(function () {
  //刷新验证码
  $("#refreshverifycode").click(function () {
    refreshverifycode(); //刷新验证码
  });
  $("#verifycode").click(function () {
    refreshverifycode(); //刷新验证码
  });
  refreshverifycode();
});

刷新验证码：

//刷新验证码
function refreshverifycode() {
  $("#verifycode").attr("src", "verifycode?t=" + new date().valueof());
}
 

判断用户输入的文本是否与验证码相同的action：

public actionresult checkvcode(string vcode)
{
  if (httpcontext.session["verifycode"].tostring().tolower() == vcode.tolower())
  {
    dictionary<string, object> dic = new dictionary<string, object>();
    dic["ok"] = true;
    return content(jsonconvert.serializeobject(dic));
  }
  else
  {
    dictionary<string, object> dic = new dictionary<string, object>();
    dic["ok"] = false;
    return content(jsonconvert.serializeobject(dic));
  }
}

以上就是本文的全部内容，希望对大家学习c#生成验证码的方法有所帮助。