code.aspx.cs

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using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

namespace book
{
	/// <summary>
	/// Code 的摘要说明。
	/// </summary>
	public class Code : System.Web.UI.Page
	{
		private void Page_Load(object sender, System.EventArgs e)
		{
			// 在此处放置用户代码以初始化页面
			string checkCode = CreateRandomCode(4);
			Session["CheckCode"] = checkCode;
			CreateImage(checkCode);
		}
		private string CreateRandomCode(int codeCount)
		{

			// 函数功能:产生数字和字符混合的随机字符串
			string allChar = "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[] allCharArray = allChar.Split(',');
			string randomCode = "";
			int temp = -1;

			Random rand = new Random();
			for(int i = 0; i < codeCount; i++)
			{
				if(temp != -1)
				{
					rand = new Random(i*temp*((int)DateTime.Now.Ticks));
				}
				int t = rand.Next(35);
				if(temp == t)
				{
					return CreateRandomCode(codeCount);
				}
				temp = t;
				randomCode += allCharArray[t];
			}
			return randomCode;
		}


		private void CreateImage(string checkCode)
		{

			// 生成图象验证码函数
			int iwidth = (int)(checkCode.Length * 11.5);
			System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 20);
			Graphics g = Graphics.FromImage(image);
			Font f = new System.Drawing.Font("Arial", 10, System.Drawing.FontStyle.Bold);
			Brush b = new System.Drawing.SolidBrush(Color.Azure);//字母白色
			//g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height);
			g.Clear(Color.Gray);//背景灰色
			g.DrawString(checkCode, f, b, 3, 3);

			Pen blackPen = new Pen(Color.Black, 0);
			Random rand = new Random();


			System.IO.MemoryStream ms = new System.IO.MemoryStream();
			image.Save(ms,System.Drawing.Imaging.ImageFormat.Jpeg);
			Response.ClearContent();
			Response.ContentType = "image/Jpeg";
			Response.BinaryWrite(ms.ToArray());
			g.Dispose();
			image.Dispose();

		}

		#region Web 窗体设计器生成的代码
		override protected void OnInit(EventArgs e)
		{
			//
			// CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
			//
			InitializeComponent();
			base.OnInit(e);
		}
		
		/// <summary>
		/// 设计器支持所需的方法 - 不要使用代码编辑器修改
		/// 此方法的内容。
		/// </summary>
		private void InitializeComponent()
		{    
			this.Load += new System.EventHandler(this.Page_Load);
		}
		#endregion
	}
}