随机笔记

public interface IRandomTextGenerator
{
/// <summary>
/// Gets or sets the settings.
/// </summary>
/// <value>The settings.</value>
RandomTextGeneratorSettings Settings { get; set; }


/// <summary>
/// Generates this instance.
/// </summary>
/// <returns></returns>
string Generate();
}

/// <summary>
/// Settings for the random text generator.
/// </summary>
public class RandomTextGeneratorSettings
{
/// <summary>
/// Gets or sets the length of random charachters to generate
/// </summary>
/// <value>The length.</value>
public int Length { get; set; }


/// <summary>
/// Gets or sets the allowed chars.
/// </summary>
/// <value>The allowed chars.</value>
public string AllowedChars { get; set; }
}

 

 

 

 

 

public class RandomTextGenerator : IRandomTextGenerator
{

/// <summary>
/// Initializes a new instance of the <see cref="RandomTextGenerator"/> class.
/// </summary>
public RandomTextGenerator()
{
Settings = new RandomTextGeneratorSettings();
Settings.Length = 5;
Settings.AllowedChars = "ABCDEFGHJKLMNPRSTUVWXY3456789";
}


#region IRandomTextGenerator Members
/// <summary>
/// Gets or sets the settings.
/// </summary>
/// <value>The settings.</value>
public RandomTextGeneratorSettings Settings { get; set; }


/// <summary>
/// Generate the random text.
/// </summary>
/// <returns></returns>
public string Generate()
{
Byte[] randomBytes = new Byte[Settings.Length];
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
rng.GetBytes(randomBytes);
char[] chars = new char[Settings.Length];
int allowedCharCount = Settings.AllowedChars.Length;
string allowedChars = Settings.AllowedChars;

for (int i = 0; i < Settings.Length; i++)
{
chars[i] = allowedChars[(int)randomBytes[i] % allowedCharCount];
}

return new string(chars);
}
#endregion
}

 

 

 

public class CaptchaImageActionResult : ActionResult
{
public string RandomWord { get; set; }

public override void ExecuteResult(ControllerContext context)
{
System.Drawing.Bitmap bmp = new System.Drawing.Bitmap((int)Math.Ceiling((RandomWord.Length * 14.5)), 22);
Graphics graphics = Graphics.FromImage(bmp);

Random random = new Random();
graphics.Clear(Color.White);
for (int i = 0; i < 20; i++)
{
int x1 = random.Next(bmp.Width);
int x2 = random.Next(bmp.Width);
int y1 = random.Next(bmp.Height);
int y2 = random.Next(bmp.Height);
if (i / 2 == 0)
{
graphics.DrawLine(new Pen(Color.DarkCyan), x1, y1, x2, y2);
}
else
{
graphics.DrawLine(new Pen(Color.Chocolate), x1, y1, x2, y2);
}
graphics.Flush();
}

Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, bmp.Width, bmp.Height), Color.Blue, Color.DarkRed, 1.2f, true);
graphics.DrawString(RandomWord, font, brush, 2, 2);
for (int i = 0; i < 5; i++)
{
int x = random.Next(bmp.Width);
int y = random.Next(bmp.Height);

bmp.SetPixel(x, y, Color.FromArgb(random.Next()));
}
graphics.DrawRectangle(new Pen(Color.Silver), 0, 0, bmp.Width - 1, bmp.Height - 1);

context.HttpContext.Response.ContentType = "image/gif";
bmp.Save(context.HttpContext.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Gif);

font.Dispose();
graphics.Dispose();
bmp.Dispose();
}
}

 

 

public CaptchaImageActionResult CaptchaImage()
{
var setting = new Framework.Utility.Captcha.RandomTextGenerator();
setting.Settings.Length = 4;
string strRandom = setting.Generate();
HttpContext.Session["RandomText"] = strRandom;
return new CaptchaImageActionResult() { RandomWord = strRandom };
}

 

 

验证码
<input value="" type="text" name="CaptchaImage" id="CaptchaImage" style="width: 60px;" />
<img style="cursor:pointer; vertical-align:middle" title="看不清楚请刷新!" id="valiCode" style="cursor: pointer;" src="/login/CaptchaImage" alt="" onclick="this.src='/login/CaptchaImage?dt='+ new Date().getTime()"/>
<span class="Types" style="color: Red">*</span>

转载于:https://www.cnblogs.com/miao-park/archive/2012/11/28/2793096.html

内容概要:本文详细探讨了基于MATLAB/SIMULINK的多载波无线通信系统仿真及性能分析,重点研究了以OFDM为代表的多载波技术。文章首先介绍了OFDM的基本原理和系统组成,随后通过仿真平台分析了不同调制方式的抗干扰性能、信道估计算法对系统性能的影响以及同步技术的实现与分析。文中提供了详细的MATLAB代码实现,涵盖OFDM系统的基本仿真、信道估计算法比较、同步算法实现和不同调制方式的性能比较。此外,还讨论了信道特征、OFDM关键技术、信道估计、同步技术和系统级仿真架构,并提出了未来的改进方向,如深度学习增强、混合波形设计和硬件加速方案。; 适合人群:具备无线通信基础知识,尤其是对OFDM技术有一定了解的研究人员和技术人员;从事无线通信系统设计与开发的工程师;高校通信工程专业的高年级本科生和研究生。; 使用场景及目标:①理解OFDM系统的工作原理及其在多径信道环境下的性能表现;②掌握MATLAB/SIMULINK在无线通信系统仿真中的应用;③评估不同调制方式、信道估计算法和同步算法的优劣;④为实际OFDM系统的设计和优化提供理论依据和技术支持。; 其他说明:本文不仅提供了详细的理论分析,还附带了大量的MATLAB代码示例,便于读者动手实践。建议读者在学习过程中结合代码进行调试和实验,以加深对OFDM技术的理解。此外,文中还涉及了一些最新的研究方向和技术趋势,如AI增强和毫米波通信,为读者提供了更广阔的视野。
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