validatecode.aspx.cs

贸易有限公司项目管理系统(C#.NET2003),供学习参考！

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 netw.admin
{
	/// <summary>
	/// 画验证码
	/// </summary>
	public partial class ValidateCode : System.Web.UI.Page
	{
		protected void Page_Load(object sender, System.EventArgs e)
		{
			

			if(!IsPostBack)
			{
				//RndNum是一个自定义函数
				//这里的数字4代表显示的是4位的验证字符串！
				//string VNum=RndNum(4); 
				string VNum=GenerateRandom(4);
				Session["VNum"] = VNum;
				Validate_Code(VNum);
			}
		}
		
		
		private void Validate_Code(string VNum) 
		{
			int Gheight=(int)(VNum.Length * 12.0);
			//gheight为图片宽度,根据字符长度自动更改图片宽度
			System.Drawing.Bitmap Img = new System.Drawing.Bitmap(Gheight,18);
			Graphics g = Graphics.FromImage(Img);
            g.DrawString(VNum, new System.Drawing.Font("Arial Black", 10), new System.Drawing.SolidBrush(Color.Red), 3, 1); 
			//在矩形内绘制字串（字串，字体，画笔颜色，左上x.左上y） 
			System.IO.MemoryStream ms=new System.IO.MemoryStream();
			Img.Save(ms,System.Drawing.Imaging.ImageFormat.Png); 
			Response.ClearContent(); //需要输出图象信息 要修改HTTP头 
			Response.ContentType="image/Png";
			Response.BinaryWrite(ms.ToArray());
			g.Dispose();
			Img.Dispose(); 
			Response.End();
		}
        
		private static char[] constant=
		{
			'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'
			
		};
		public static string GenerateRandom(int Length)
		{   
			System.Text.StringBuilder newRandom = new System.Text.StringBuilder(62);
			Random rd= new Random();
			for(int i=0;i<Length;i++)
			{
				newRandom.Append(constant[rd.Next(62)]);
			}
			return newRandom.ToString();
		}

	}}