C# 从服务器下载文件

一、//TransmitFile实现下载

    protected void Button1_Click(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：

        */

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

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

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

        Response.TransmitFile(filename);

    }

二、//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();

    }

三、   //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 = ;//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 >  && Response.IsClientConnected)

            {

                int lengthRead = iStream.Read(buffer, , Convert.ToInt32(ChunkSize));//读取的大小

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

                Response.Flush();

                dataLengthToRead = dataLengthToRead - lengthRead;

            }

            Response.Close();

        }

    }

四、//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, , 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();

    }

//----------------------------------------------------------

public void DownloadFile( System.Web.UI.Page WebForm,String FileNameWhenUserDownload ,String FileBody )

{

　　WebForm.Response.ClearHeaders();

　　WebForm.Response.Clear();

　　WebForm.Response.Expires = ;

　　WebForm.Response.Buffer = true;

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

　　//'文件名称

　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='"+System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8)+"'");

　　WebForm.Response.ContentType = "Application/octet-stream";

　　//'文件内容

　　WebForm.Response.Write(FileBody);//-----------

    WebForm.Response.End();

}

//上面这段代码是下载一个动态产生的文本文件，若这个文件已经存在于服务器端的实体路径，则可以通过下面的函数：

public void DownloadFileByFilePath( System.Web.UI.Page WebForm,String FileNameWhenUserDownload ,String FilePath )

{

　　WebForm.Response.ClearHeaders();

　　WebForm.Response.Clear();

　　WebForm.Response.Expires = ;

    WebForm.Response.Buffer = true;

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

　　//文件名称

　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='" + System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8) +"'" );

　　WebForm.Response.ContentType = "Application/octet-stream";

　　//文件内容

　　WebForm.Response.Write(System.IO.File.Rea}dAllBytes(FilePath));//---------

　　WebForm.Response.End();

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