第一种：
using System.Drawing;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
CreateCheckCodeImage(GenerateCheckCode());
}
private string GenerateCheckCode()
{
//创建整型型变量
int number;
//创建字符型变量
char code;
//创建字符串变量并初始化为空
string checkCode = String.Empty;
//创建Random对象
Random random = new Random();
//使用For循环生成4个数字
for (int i = 0; i < 4; i++)
{
//生成一个随机数
number = random.Next();
//将数字转换成为字符型
code = (char)(‘0‘ + (char)(number % 10));
checkCode += code.ToString();
}
//将生成的随机数添加到Cookies中
Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));
//返回字符串
return checkCode;
}
private void CreateCheckCodeImage(string checkCode)
{
//判断字符串不等于空和null
if (checkCode == null || checkCode.Trim() == String.Empty)
return;
//创建一个位图对象
System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
//创建Graphics对象
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);
//画图片的背景噪音线
for (int i = 0; i < 2; 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.Black), x1, y1, x2, y2);
}
Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold));
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
g.DrawString(checkCode, font, brush, 2, 2);
//画图片的前景噪音点
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);
//将图片输出到页面上
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
Response.ClearContent();
Response.ContentType = "image/Gif";
Response.BinaryWrite(ms.ToArray());
}
finally
{
g.Dispose();
image.Dispose();
}
}
}
第二种：
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
Label1.Text =RandomNum(4);//产生验证码
}
}
public string RandomNum(int n)
{
string strchar="0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z";
string[] VcArray=strchar.Split(‘,‘);
string VNum="";
int temp=-1;//记录上次随机数值，尽量避免产生几个一样的随机数
//采用一个简单的算法以保证生成随机数的不同
Random rand=new Random();
for(int i=1;i<n+1;i++)
{
if(temp!=-1)
{
rand=new Random(i * temp *(int)DateTime.Now.Ticks);
}
int t=rand.Next(61);
if(temp!=-1&&temp==t)
{
return RandomNum(n);
}
temp=t;
VNum+=VcArray[t];
}
return VNum; //返回生成的随机数
}
第三种：
using System.Drawing;
using System.Drawing.Imaging;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Session["code"] = RandNum(4);
ValidateCode(Session["code"].ToString(), 40, 20, "黑体", 10, "#FFFFFF");
}
private string RandNum(int VcodeNum)
{
string Vchar = "0,1,2,3,4,5,6,7,8,9";
string[] VcArray = Vchar.Split(‘,‘);//拆分成数组
string VNum = "";
int temp = -1;//记录上次随机数值，尽量避避免生产几个一样的随机数
Random rand = new Random();
//采用一个简单的算法以保证生成随机数的不同
for (int i = 0; i < VcodeNum; i++)
{
if (temp != -1)
{
rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));
}
int t = rand.Next(VcArray.Length - 1);
if (temp != -1 && temp == t)
{
return RandNum(VcodeNum);
}
temp = t;
VNum += VcArray[t];
}
return VNum;
}
private void ValidateCode(string VNum, int w, int h, string font, int fontSize, string bgColor)
{
Bitmap Img = new Bitmap(w, h);//生成图像的实例
Graphics g = Graphics.FromImage(Img);//从Img对象生成新的Graphics对象
g.Clear(ColorTranslator.FromHtml(bgColor));//背景颜色
Font f = new Font(font, fontSize);//生成Font类的实例
SolidBrush s = new SolidBrush(Color.Black);//生成笔刷类的实例
g.DrawString(VNum, f, s, 3, 3);//将VNum写入图片中
Img.Save(Response.OutputStream, ImageFormat.Jpeg);//将此图像以Jpeg图像文件的格式保存到流中
Response.ContentType = "image/Jpeg";
//回收资源
g.Dispose();
Img.Dispose();
Response.End();
}
}
几种验证码源码