<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>        
     
    
      
        
      
    
     

　　

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;/* HttpHandler1 * HttpHandler是对请求的响应，可以输出普通的html内容，也可以输出图片，也可以输出一个文件(下载) * 输出一幅动态创建的图片(能看懂就可以) *  * 案例1: 图片中显示的访问者信息 * 案例2: 填入朋友的姓名就能生成恶搞的图片链接 * 网上看到的注册，登陆时候的验证码也是动态生成的图片，55.la也是这样实现的原理 * *  * HttpHandler实现文件下载 * 如果HttpHandler输出的是html，txt, jpeg等类型的信息，那么浏览器会直接显示，如果希望弹出保存对话框，则需要添加 * Header: string encodeFileName = HttpUtility.UrlEncode("过滤语.txt");  * Response.AddHeader("Content-Disposition", string.Format("attachment;filename=\"{0}\"",encodeFileName)); * 其中filename后为编码后的文件名，filename段为建议的保存文件名 *  * 动态输出用处，不用再把资原保存到磁盘上再输出(不会有文件重名的问题，文件不生成在服务器端) * 案例: 点周链接弹出图片下载对话框 *  * 练习: 用NPOI动态生成一个Execel表然后弹出对话框让用户下载，文件名是"用户列表.xls" *  * 练习: 从数据库用户表导出数据到Excel文件，让用户下载， mdf放到App_Data下,asp.net不用那段设置DataDirectory的代码,用DataReader的方式读取数据 *  * 练习: 用户表增加一个级别字段，只有登陆用户才能下载images下的图片文件(session中标识是否登录),如果用户没有登录则首先重定向到登录界面让用户登录，用户 * 登录成功则跳转到下载列表页面，下载链接固定写好即可，如果登妹用户是普通用户则在图片左下解加上"免费用户试用"的字样 * 练习: 给上面的程序加上登录验证码 *  */public partial class _Default : System.Web.UI.Page{    protected void Page_Load(object sender, EventArgs e)    {        string dataDir = AppDomain.CurrentDomain.BaseDirectory;        if (dataDir.EndsWith(@"\bin\Debug\")            || dataDir.EndsWith(@"\bin\Release\"))        {            dataDir = System.IO.Directory.GetParent(dataDir).Parent.Parent.FullName;            AppDomain.CurrentDomain.SetData("DataDirectory", dataDir);        }    }    /*             using (SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=E:\MyProjects\C#net传智播客\第十一节asp.net中级\导出Excel\App_Data\Database.mdf;Integrated Security=True;User Instance=True"))        {            conn.Open();            using (SqlCommand cmd = conn.CreateCommand())             {                cmd.CommandText = "select * FROM T_User";                using(SqlDataReader reader = cmd.ExecuteReader())                {                    HSSFRow _row = sheet.CreateRow(0);                    _row.CreateCell(0, HSSFCell.CELL_TYPE_STRING).SetCellValue("ID");                    _row.CreateCell(1, HSSFCell.CELL_TYPE_STRING).SetCellValue("用户名");                    _row.CreateCell(2, HSSFCell.CELL_TYPE_STRING).SetCellValue("性别");                    int rownum = 1;                    while (reader.Read())                     {                        Int64 id = reader.GetInt64(reader.GetOrdinal("id"));                        string name = reader.GetString(reader.GetOrdinal("name"));                        string sex = reader.GetString(reader.GetOrdinal("sex"));                        HSSFRow row = sheet.CreateRow(rownum);                        row.CreateCell(0, HSSFCell.CELL_TYPE_STRING).SetCellValue(id);                        row.CreateCell(1, HSSFCell.CELL_TYPE_STRING).SetCellValue(name);                        row.CreateCell(2, HSSFCell.CELL_TYPE_STRING).SetCellValue(sex);                        rownum++;                        //context.Response.Write("id:"+id+", name:"+name+", sex="+sex+"
");                    }                }            }        }             */}

　　

<%@ WebHandler Language="C#" Class="HttpHandler1" %>using System;using System.Web;public class HttpHandler1 : IHttpHandler {        public void ProcessRequest (HttpContext context) {        context.Response.ContentType = "image/JPEG";        //context.Response.Write("Hello World");        using (System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(300, 300))         {            using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap))             {                g.DrawString("IP:" + context.Request.UserHostAddress, new System.Drawing.Font("宋体", 30), System.Drawing.Brushes.Red, 0, 0);                g.DrawString("操作系统:" + context.Request.Browser.Platform, new System.Drawing.Font("宋体", 30), System.Drawing.Brushes.Red, 0, 100);                g.DrawString("浏览器:" + context.Request.Browser.Type, new System.Drawing.Font("宋体", 30), System.Drawing.Brushes.Red, 0, 150);            }            bitmap.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);        }    }     public bool IsReusable {        get {            return false;        }    }}

　　

<%@ WebHandler Language="C#" Class="HttpHandler2" Debug=true %>using System;using System.Web;public class HttpHandler2 : IHttpHandler {        public void ProcessRequest (HttpContext context) {        context.Response.ContentType = "image/JPEG";        string name = context.Request["name"];        string imgfile = HttpContext.Current.Server.MapPath("3.jpg");        using (System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(imgfile))         {            using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap))             {                g.DrawString(name, new System.Drawing.Font("宋体",30), System.Drawing.Brushes.Red, 50,50);            }            bitmap.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);        }            }     public bool IsReusable {        get {            return false;        }    }}

　　

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="xiazan.aspx.cs" Inherits="xiazan" %>          图片1   txt   图片3   图片4

　　

<%@ WebHandler Language="C#" Class="xiazan" %>using System;using System.Web;public class xiazan : IHttpHandler {        public void ProcessRequest (HttpContext context) {        context.Response.ContentType = "image/JPEG";        //context.Response.Write("Hello World");        //这里如果用中文文件名的话，有可能出现乱码        //context.Response.AddHeader("Content-Disposition", "attachment;filename=呵呵.jpg");        context.Response.AddHeader("Content-Disposition", HttpUtility.UrlEncode("attachment;filename=哥哥哥哥.jpg"));                context.Response.WriteFile("3.jpg");    }     public bool IsReusable {        get {            return false;        }    }}