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先把有問(wèn)題的代碼貼出來(lái)吧

 

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.IO;

 

namespace infoPlatClient.NetDisk

{

    public partial class downLoad : Com.DRPENG.Common.WebStruct.BaseForm

    {

 

        /// <summary>

        /// 取得要下載文件的路徑

        /// </summary>

        private string fileRpath

        {

            get

            {

                return Request["fileRpath"] == null ? "" : Request["fileRpath"];

            }

        }

        /// <summary>

        /// 取得要下載文件的名稱

        /// </summary>

      

        protected void Page_Load(object sender, EventArgs e)

        {

                if (!IsPostBack)

                this.DownloadFile();

        }

        public void DownloadFile()

        {

 

                Response.ClearHeaders();

                Response.Clear();

                Response.Expires = 0;

                Response.Buffer =true;

                Response.AddHeader("Accept-Language", "zh-tw");

                string name = System.IO.Path.GetFileName(fileRpath);

                System.IO.FileStream files = new FileStream(fileRpath, FileMode.Open, FileAccess.Read, FileShare.Read);

                byte[] byteFile=null;

                if (files.Length == 0)

                {

                    byteFile=new byte[1];

                }

                else

                {

                    byteFile = new byte[files.Length];

                }

                files.Read(byteFile, 0, (int)byteFile.Length);

                files.Close();

            

                Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(name, System.Text.Encoding.UTF8));

                Response.ContentType = "application/octet-stream;charset=gbk";

                Response.BinaryWrite(byteFile);

                Response.End();

             

        }

    }

}

 

 之前一直用這種下載方式，可是有一次用戶上傳了一個(gè)700Mb的文件時(shí)報(bào)內(nèi)存溢出的問(wèn)題，分析了一下原因，用戶的內(nèi)存只有256M，而下載文件時(shí)要?jiǎng)?chuàng)建內(nèi)存流，導(dǎo)致了內(nèi)存溢出。

 

解決方案:1>WriteFile分塊下載，就是每次下載指定數(shù)量的多件;

 

             2>通過(guò)超鏈接的方式;

 

             lblDownLoad.Text = "<a href='" + drv["VPath"].ToString() + "'>下載</a>"

 

下面是四種實(shí)現(xiàn)文件下載的方式:

 

using System;

using System.Data;

using System.Configuration;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.IO;

 

public partial class _Default : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

 

    }

 

    //TransmitFile實(shí)現(xiàn)下載

    protected void Button1_Click(object sender, EventArgs e)

    {

        /*

         微軟為Response對(duì)象提供了一個(gè)新的方法TransmitFile來(lái)解決使用Response.BinaryWrite

         下載超過(guò)400mb的文件時(shí)導(dǎo)致Aspnet_wp.exe進(jìn)程回收而無(wú)法成功下載的問(wèn)題。

         代碼如下：

         */

 

        Response.ContentType = "application/x-zip-compressed";

        Response.AddHeader("Content-Disposition", "attachment;filename=z.zip");

        string filename = Server.MapPath("DownLoad/z.zip");

        Response.TransmitFile(filename);

    }

 

    //WriteFile實(shí)現(xiàn)下載

    protected void Button2_Click(object sender, EventArgs e)

    {

        /*

         using System.IO;

        

         */

 

        string fileName ="asd.txt";//客戶端保存的文件名

        string filePath=Server.MapPath("DownLoad/aaa.txt");//路徑

 

        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分塊下載

    protected void Button3_Click(object sender, EventArgs e)

    {

 

        string fileName = "aaa.txt";//客戶端保存的文件名

        string filePath = Server.MapPath("DownLoad/aaa.txt");//路徑

 

        System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);

 

        if (fileInfo.Exists == true)

        {

            const long ChunkSize = 102400;//100K 每次讀取文件，只讀取100K，這樣可以緩解服務(wù)器的壓力

            byte[] buffer = new byte[ChunkSize];

 

            Response.Clear();

            System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);

            long dataLengthToRead = iStream.Length;//獲取下載的文件總大小

            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));//讀取的大小

                Response.OutputStream.Write(buffer, 0, lengthRead);

                Response.Flush();

                dataLengthToRead = dataLengthToRead - lengthRead;

            }

            Response.Close();

        }

    }

 

    //流方式下載

    protected void Button4_Click(object sender, EventArgs e)

    {

        string fileName = "aaa.txt";//客戶端保存的文件名

        string filePath = Server.MapPath("DownLoad/aaa.txt");//路徑

 

        //以字符流的形式下載文件

        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";

        //通知瀏覽器下載文件而不是打開

        Response.AddHeader("Content-Disposition", "attachment;  filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));

        Response.BinaryWrite(bytes);

        Response.Flush();

        Response.End();

 

    }

}