How to download large files using ASP. Net

How to download large files using ASP. Net

This article mainly introduces the implementation of ASP. Net to download large files, and analyzes in detail the ideas and precautions for downloading large files. For more information, see

This document describes how to download large files using ASP. Net. Share it with you for your reference. The specific analysis is as follows:

When our website needs to support downloading large files, if it is not controlled, it may cause a user to have no response when accessing the download page, causing the browser to crash. You can refer to the following code to avoid this problem.

Several notes about this Code:

1. Divide the data into smaller parts and move it to the output stream for download to obtain the data.

2. Specify Response. ContentType Based on the downloaded file type. (Refer to the OSChina URL to find the comparison table for most file types: http://tool.oschina.net/commons)

3. Remember to call response. Flush () every time you finish writing Response ()

4. Using Response. IsClientConnected in the loop download process can help the program detect whether the connection is normal as soon as possible. If it is abnormal, You can discard the download as soon as possible to release the occupied server resources.

5. After the download is complete, call Response. End () to ensure that the current thread can be terminated.

The Code is as follows:

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 10 K 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", "attachment; 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 ();

}

}

}

}

 

I hope this article will help you design your asp.net program.