一般处理程序生成验证码图片

    public void ProcessRequest (HttpContext context) {
        context.Response.ContentType = "image/jpeg";
        //获得验证码符号
        string code = GetCode();
        Image img = GetImage(code);
        //保存生成的验证码图片
        img.Save(context.Response.OutputStream, ImageFormat.Jpeg);
    }

    /// <summary>
    /// 生成验证码图片
    /// <summary>
    private Image GetImage(string code) {
        Bitmap bitmap = new Bitmap(85, 40);
        //画板
        Graphics g = Graphics.FromImage(bitmap);
        //在画板上输出符号
        g.DrawString(code, new Font("楷体", 24), Brushes.Green, 5, 5);
        return bitmap;
    }

    /// <summary>
    /// 获取验证码
    /// </summary>
    /// <returns></returns>
    private string GetCode() {
        string str = "0123456789abcdefghigklmnopqrstuvwxyzABCDEFGHIGKLMNOPQRSTUVWXYZ";
        string code = "";
        Random r = new Random();
        for (int i = 0; i < 4; i++) {
            //存储验证码符号
            code += str[r.Next(0, str.Length)];
        }
        return code;
    }

　　

下面是我用一般处理程序生成的10张验证码图片（给大家看看效果）