Asp.net生成验证码的类

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Text;
using System.Web;

namespace WanJia.CommonUtility
{
/// <summary>
/// VerifyCode
/// </summary>
public class VerifyCode
{
#region Private Field & Public Property
//随机种子
private Random objRandom = new Random();

#region 验证码长度
//验证码长度
private int length = 4;

/// <summary>
/// 验证码长度(默认为4)
/// </summary>
public int Length
{
get { return this.length; }
set { this.length = value; }
}
#endregion

#region 验证码字符串
//验证码字符串
private string verifyCodeText = null;

/// <summary>
/// 验证码字符串
/// </summary>
public string VerifyCodeText
{
get { return this.verifyCodeText; }
set { this.verifyCodeText = value; }
}
#endregion

#region 是否加入小写字母
//是否加入小写字母
private bool addLowerLetter = false;

/// <summary>
/// 是否加入小写字母(不包括o)
/// </summary>
public bool AddLowerLetter
{
get { return this.addLowerLetter; }
set { this.addLowerLetter = value; }
}
#endregion

#region 是否加入大写字母
//是否加入大写字母
private bool addUpperLetter = false;

/// <summary>
/// 是否加入大写字母(不包括O)
/// </summary>
public bool AddUpperLetter
{
get { return this.addUpperLetter; }
set { this.addUpperLetter = value; }
}
#endregion

#region 字体大小
//字体大小
private int fontSize = 18;

/// <summary>
/// 字体大小(默认为18)
/// </summary>
public int FontSize
{
get { return this.fontSize; }
set { this.fontSize = value; }
}
#endregion

#region 字体颜色
//字体颜色
private Color fontColor = Color.Blue;

/// <summary>
/// 字体颜色(默认为Blue)
/// </summary>
public Color FontColor
{
get { return this.fontColor; }
set { this.fontColor = value; }
}
#endregion

#region 字体类型
//字体类型
private string fontFamily = "Verdana";

/// <summary>
/// 字体类型(默认为Verdana)
/// </summary>
public string FontFamily
{
get { return this.fontFamily; }
set { this.fontFamily = value; }
}
#endregion

#region 背景色
//背景色
private Color backgroundColor = Color.AliceBlue;

/// <summary>
/// 背景色(默认为AliceBlue)
/// </summary>
public Color BackgroundColor
{
get { return this.backgroundColor; }
set { this.backgroundColor = value; }
}
#endregion

#region 前景噪点数量
//前景噪点数量
private int foreNoisePointCount = 2;

/// <summary>
/// 前景噪点数量(默认为2)
/// </summary>
public int ForeNoisePointCount
{
get { return this.foreNoisePointCount; }
set { this.foreNoisePointCount = value; }
}
#endregion

#region 随机码的旋转角度
//随机码的旋转角度
private int randomAngle = 40;

/// <summary>
/// 随机码的旋转角度(默认为40度)
/// </summary>
public int RandomAngle
{
get { return this.randomAngle; }
set { this.randomAngle = value; }
}
#endregion
#endregion

#region Constructor Method
public VerifyCode()
{
this.GetVerifyCodeText();
}
#endregion

#region Private Method
/// <summary>
/// 得到验证码字符串
/// </summary>
private void GetVerifyCodeText()
{
//没有外部输入验证码时随机生成
if (String.IsNullOrEmpty(this.verifyCodeText))
{
StringBuilder objStringBuilder = new StringBuilder();

//加入数字1-9
for (int i = 1; i <= 9; i++)
{
objStringBuilder.Append(i.ToString());
}

//加入大写字母A-Z，不包括O
if (this.addUpperLetter)
{
char temp = ' ';

for (int i = 0; i < 26; i++)
{
temp = Convert.ToChar(i + 65);

//如果生成的字母不是'O'
if (!temp.Equals('O'))
{
objStringBuilder.Append(temp);
}
}
}

//加入小写字母a-z，不包括o
if (this.addLowerLetter)
{
char temp = ' ';

for (int i = 0; i < 26; i++)
{
temp = Convert.ToChar(i + 97);

//如果生成的字母不是'o'
if (!temp.Equals('o'))
{
objStringBuilder.Append(temp);
}
}
}

//生成验证码字符串
{
int index = 0;

for (int i = 0; i < length; i++)
{
index = objRandom.Next(0, objStringBuilder.Length);

this.verifyCodeText += objStringBuilder[index];

objStringBuilder.Remove(index, 1);
}
}
}
}

/// <summary>
/// 得到验证码图片
/// </summary>
private Bitmap GetVerifyCodeImage()
{
Bitmap result = null;

//创建绘图
result = new Bitmap(this.verifyCodeText.Length * 16, 25);

using (Graphics objGraphics = Graphics.FromImage(result))
{
objGraphics.SmoothingMode = SmoothingMode.HighQuality;

//清除整个绘图面并以指定背景色填充
objGraphics.Clear(this.backgroundColor);

//创建画笔
using (SolidBrush objSolidBrush = new SolidBrush(this.fontColor))
{
this.AddForeNoisePoint(result);

this.AddBackgroundNoisePoint(result, objGraphics);

//文字居中
StringFormat objStringFormat = new StringFormat(StringFormatFlags.NoClip);

objStringFormat.Alignment = StringAlignment.Center;
objStringFormat.LineAlignment = StringAlignment.Center;

//字体样式
Font objFont = new Font(this.fontFamily, objRandom.Next(this.fontSize - 3, this.fontSize), FontStyle.Regular);

//验证码旋转，防止机器识别
char[] chars = this.verifyCodeText.ToCharArray();

for (int i = 0; i < chars.Length; i++)
{
//转动的度数
float angle = objRandom.Next(-this.randomAngle, this.randomAngle);

objGraphics.TranslateTransform(12, 12);
objGraphics.RotateTransform(angle);
objGraphics.DrawString(chars[i].ToString(), objFont, objSolidBrush, -2, 2, objStringFormat);
objGraphics.RotateTransform(-angle);
objGraphics.TranslateTransform(2, -12);
}
}
}

return result;
}

/// <summary>
/// 添加前景噪点
/// </summary>
/// <param name="objBitmap"></param>
private void AddForeNoisePoint(Bitmap objBitmap)
{
for (int i = 0; i < objBitmap.Width * this.foreNoisePointCount; i++)
{
objBitmap.SetPixel(objRandom.Next(objBitmap.Width), objRandom.Next(objBitmap.Height), this.fontColor);
}
}

/// <summary>
/// 添加背景噪点
/// </summary>
/// <param name="objBitmap"></param>
/// <param name="objGraphics"></param>
private void AddBackgroundNoisePoint(Bitmap objBitmap, Graphics objGraphics)
{
using (Pen objPen = new Pen(Color.Azure, 0))
{
for (int i = 0; i < objBitmap.Width * 2; i++)
{
objGraphics.DrawRectangle(objPen, objRandom.Next(objBitmap.Width), objRandom.Next(objBitmap.Height), 1, 1);
}
}

}
#endregion

#region Public Method
/// <summary>
/// 输出验证码图片
/// </summary>
/// <param name="objHttpResponse">Http响应实例</param>
/// <returns>输出是否成功</returns>
public bool OutputImage(HttpResponse objHttpResponse)
{
bool result = false;

using (Bitmap objBitmap = this.GetVerifyCodeImage())
{
if (objBitmap != null)
{
using (MemoryStream objMS = new MemoryStream())
{
objBitmap.Save(objMS, ImageFormat.Jpeg);

HttpContext.Current.Response.ClearContent();
HttpContext.Current.Response.ContentType = "image/Jpeg";
HttpContext.Current.Response.BinaryWrite(objMS.ToArray());
HttpContext.Current.Response.Flush();
HttpContext.Current.Response.End();

result = true;
}
}
}

return result;
}
#endregion
}
}