<%@ WebHandler Language="C#" Class="AttachmentHandler" %>using System;using System.Collections.Generic;using System.Web;using System.Data.SqlClient;using System.Configuration;public class AttachmentHandler : IHttpHandler{ public void ProcessRequest(HttpContext context) { string workflowID = context.Request["guid"]; string tableName = context.Request["tb"]; if (string.IsNullOrEmpty(workflowID) || string.IsNullOrEmpty(tableName)) context.Response.End(); using (SqlConnection conn = new SqlConnection(ConfigurationManager.AppSettings["db"])) { conn.Open(); var cmdText = string.Format(@"select FileName,Attachment from {0} where WorkflowID='{1}'" , tableName, workflowID); SqlCommand cmd = new SqlCommand(cmdText, conn); SqlDataReader dr = cmd.ExecuteReader(); if (dr.Read()) { if (!Convert.IsDBNull(dr["Attachment"])) { context.Response.BinaryWrite((byte[])dr["Attachment"]); context.Response.AppendHeader("Content-Disposition" , string.Format("attachment;filename={0}" , HttpUtility.UrlEncode(dr["FileName"].ToString()))); } dr.Close(); dr = null; context.Response.End(); } conn.Close(); } } public bool IsReusable { get { return false; } }} Ref:TransmitFile
View Code //TransmitFile实现下载 protected void Button1_Click1(object sender, EventArgs e) { /* 微软为Response对象提供了一个新的方法TransmitFile来解决使用Response.BinaryWrite 下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。 代码如下： */ string strFileName = "xxx.ppt"; Response.ContentType = "application/x-zip-compressed"; //Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312"); string filename = BLL.Config.PART_EM_UPLOAD_DOC + strFileName; //BLL.Config.PART_EM_UPLOAD_DOC 为路径 ("D:/EMUploadDoc/") Response.AddHeader("Content-Disposition", "attachment;filename=" +Server.UrlPathEncode(strFileName)); //Server.UrlPathEncode()解决文件名的乱码问题. Response.TransmitFile(filename); } //WriteFile实现下载 protected void Button2_Click(object sender, EventArgs e) { /* using System.IO; */ string fileName = "asd.txt";//客户端保存的文件名 string filePath = Server.MapPath("DownLoad/aaa.txt");//路径 FileInfo fileInfo = new FileInfo(filePath); Response.Clear(); Response.ClearContent(); Response.ClearHeaders(); Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName); Response.AddHeader("Content-Length", fileInfo.Length.ToString()); Response.AddHeader("Content-Transfer-Encoding", "binary"); Response.ContentType = "application/octet-stream"; Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312"); Response.WriteFile(fileInfo.FullName); Response.Flush(); Response.End(); } //WriteFile分块下载 protected void Button3_Click(object sender, EventArgs e) { string fileName = "aaa.txt";//客户端保存的文件名 string filePath = Server.MapPath("DownLoad/aaa.txt");//路径 System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath); if (fileInfo.Exists == true) { const long ChunkSize = 102400;//100K 每次读取文件，只读取100Ｋ，这样可以缓解服务器的压力 byte[] buffer = new byte[ChunkSize]; Response.Clear(); System.IO.FileStream iStream = System.IO.File.OpenRead(filePath); long dataLengthToRead = iStream.Length;//获取下载的文件总大小 Response.ContentType = "application/octet-stream"; Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName)); while (dataLengthToRead > 0 && Response.IsClientConnected) { int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//读取的大小 Response.OutputStream.Write(buffer, 0, lengthRead); Response.Flush(); dataLengthToRead = dataLengthToRead - lengthRead; } Response.Close(); } } //流方式下载 protected void Button4_Click(object sender, EventArgs e) { string fileName = "aaa.txt";//客户端保存的文件名 string filePath = Server.MapPath("DownLoad/aaa.txt");//路径 //以字符流的形式下载文件 FileStream fs = new FileStream(filePath, FileMode.Open); byte[] bytes = new byte[(int)fs.Length]; fs.Read(bytes, 0, bytes.Length); fs.Close(); Response.ContentType = "application/octet-stream"; //通知浏览器下载文件而不是打开 Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8)); Response.BinaryWrite(bytes); Response.Flush(); Response.End(); }