• Asp.Net文件下载


    <%@ 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();
    
        }
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  • 原文地址:https://www.cnblogs.com/ncore/p/2766625.html
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