asp.net mvc验证码类使用

验证码类

namespace qjw.verifycode
{
  //用法：
  //public filecontentresult createvalidate()
  //{
  //  validatecode vcode = new validatecode();
  //  string code = vcode.createvalidatecode(5);
  //  session["validatecode"] = code;
  //  byte[] bytes = vcode.createvalidategraphic(code);
  //  return file(bytes, "image/jpeg");
  //}


  public class validatecode
  {
    public validatecode()
    {
    }
    /// <summary>
    /// 验证码的最大长度
    /// </summary>
    public int maxlength
    {
      get { return 10; }
    }
    /// <summary>
    /// 验证码的最小长度
    /// </summary>
    public int minlength
    {
      get { return 1; }
    }
    /// <summary>
    /// 生成验证码
    /// </summary>
    /// <param name="length">指定验证码的长度</param>
    /// <returns></returns>
    public string createvalidatecode(int length)
    {
      int[] randmembers = new int[length];
      int[] validatenums = new int[length];
      string validatenumberstr = "";
      //生成起始序列值
      int seekseek = unchecked((int)datetime.now.ticks);
      random seekrand = new random(seekseek);
      int beginseek = (int)seekrand.next(0, int32.maxvalue - length * 10000);
      int[] seeks = new int[length];
      for (int i = 0; i < length; i++)
      {
        beginseek += 10000;
        seeks[i] = beginseek;
      }
      //生成随机数字
      for (int i = 0; i < length; i++)
      {
        random rand = new random(seeks[i]);
        int pownum = 1 * (int)math.pow(10, length);
        randmembers[i] = rand.next(pownum, int32.maxvalue);
      }
      //抽取随机数字
      for (int i = 0; i < length; i++)
      {
        string numstr = randmembers[i].tostring();
        int numlength = numstr.length;
        random rand = new random();
        int numposition = rand.next(0, numlength - 1);
        validatenums[i] = int32.parse(numstr.substring(numposition, 1));
      }
      //生成验证码
      for (int i = 0; i < length; i++)
      {
        validatenumberstr += validatenums[i].tostring();
      }
      return validatenumberstr;
    }
    /// <summary>
    /// 创建验证码的图片
    /// </summary>
    /// <param name="containspage">要输出到的page对象</param>
    /// <param name="validatenum">验证码</param>
    public byte[] createvalidategraphic(string validatecode)
    {
      bitmap image = new bitmap((int)math.ceiling(validatecode.length * 12.0), 22);
      graphics g = graphics.fromimage(image);
      try
      {
        //生成随机生成器
        random random = new random();
        //清空图片背景色
        g.clear(color.white);
        //画图片的干扰线
        for (int i = 0; i < 25; 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);
        }
        font font = new font("arial", 12, (fontstyle.bold | fontstyle.italic));
        lineargradientbrush brush = new lineargradientbrush(new rectangle(0, 0, image.width, image.height),
         color.blue, color.darkred, 1.2f, true);
        g.drawstring(validatecode, font, brush, 3, 2);
        //画图片的前景干扰点
        for (int i = 0; i < 100; i++)
        {
          int x = random.next(image.width);
          int y = random.next(image.height);
          image.setpixel(x, y, color.fromargb(random.next()));
        }
        //画图片的边框线
        g.drawrectangle(new pen(color.silver), 0, 0, image.width - 1, image.height - 1);
        //保存图片数据
        memorystream stream = new memorystream();
        image.save(stream, imageformat.jpeg);
        //输出图片流
        return stream.toarray();
      }
      finally
      {
        g.dispose();
        image.dispose();
      }
    }
    /// <summary>
    /// 得到验证码图片的长度
    /// </summary>
    /// <param name="validatenumlength">验证码的长度</param>
    /// <returns></returns>
    public static int getimagewidth(int validatenumlength)
    {
      return (int)(validatenumlength * 12.0);
    }
    /// <summary>
    /// 得到验证码的高度
    /// </summary>
    /// <returns></returns>
    public static double getimageheight()
    {
      return 22.5;
    }
  }
}

使用方法

    public filecontentresult createvalidate()
    {
      validatecode vcode = new validatecode();
      string code = vcode.createvalidatecode(5);
      session["validatecode"] = code;
      byte[] bytes = vcode.createvalidategraphic(code);

      return file(bytes, "image/jpeg");
    }

html
<a href="javascript:;" onclick="reloadcode();"><img id="safecode" src="/common/createvalidate" alt="" /></a> 
视图js 

function reloadcode() {
    var verify = document.getelementbyid('safecode');
    verify.setattribute('src', '/common/createvalidate?' + math.random());
  }

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