大文件下载可能遇到很多bug,终止,不能断点续传什么的.下面介绍个方法.

按照codego.net里所介绍的方法,整理如下流程,一共5个步骤,即可asp.net下载大文件实现


1. 将数据分成较小的部分，然后将其移动到输出流以供下载，从而获取这些数据。

2. 根据下载的文件类型来指定 Response.ContentType 。

3. 在每次写完response时记得调用 Response.Flush()

4. 在循环下载的过程中使用 Response.IsClientConnected 这个判断可以帮助程序尽早发现连接是否正常。若不正常，可以及早的放弃下载，以释放所占用的服务器资源。

5. 在下载结束后，需要调用 Response.End() 来保证当前线程可以在最后被终止掉。


using System;


namespace WebApplication1

{

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

{

protected void Page_Load(object sender, EventArgs e)

{

System.IO.Stream iStream = null;


// Buffer to read 10K bytes in chunk:

byte[] buffer = new Byte[10000];


// Length of the file:

int length;


// Total bytes to read.

long dataToRead;


// Identify the file to download including its path.

string filepath = Server.MapPath("/") +"./Files/TextFile1.txt";


// Identify the file name.

string filename = System.IO.Path.GetFileName(filepath);


try

{

// Open the file.

iStream = new System.IO.FileStream(filepath, System.IO.FileMode.Open,

System.IO.FileAccess.Read, System.IO.FileShare.Read);


// Total bytes to read.

dataToRead = iStream.Length;


Response.Clear();

Response.ClearHeaders();

Response.ClearContent();

Response.ContentType = "text/plain"; // Set the file type

Response.AddHeader("Content-Length", dataToRead.ToString());

Response.AddHeader("Content-Disposition", "p_w_upload; filename=" + filename);


// Read the bytes.

while (dataToRead > 0)

{

// Verify that the client is connected.

if (Response.IsClientConnected)

{

// Read the data in buffer.

length = iStream.Read(buffer, 0, 10000);


// Write the data to the current output stream.

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


// Flush the data to the HTML output.

Response.Flush();


buffer = new Byte[10000];

dataToRead = dataToRead - length;

}

else

{

// Prevent infinite loop if user disconnects

dataToRead = -1;

}

}

}

catch (Exception ex)

{

// Trap the error, if any.

Response.Write("Error : " + ex.Message);

}

finally

{

if (iStream != null)

{

//Close the file.

iStream.Close();

}


Response.End();

}

}

}

}