ASP.NET中下载文件的几种方式

//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 = "三部闲置设备管理系统操作手册IEMS.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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