ASP. NET implements resumable file transfer code

When downloading an object, you can use resumable upload to continue downloading the object that was not downloaded last time. This feature is very important when downloading the object. Here I will introduce a simple method to implement the resumable upload function, which is only for beginners.

Here, I add an HTTP header to the output stream through the AddHeader method in the Response class. The HTTP header consists of header information and body information. The two are separated by a blank line. Here, the Range segment is added to the header to indicate where the client wants to continue downloading to implement the Resume function.
Let's get started.
1. Create a new home page with a name.
2. Add a LinkButton to the page to execute the implementation process.
3. Implement the resumable upload function in the Click Event of the LinkButton.
The Code is as follows:
In addition, do not forget to reference the System. IO namespace. Here we only paste the background implementation code (the front-end will not be able to go back to learning ...)

The Code is as follows:

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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; Public partial class DFile: System. Web. UI. Page { Protected void Page_Load (object sender, EventArgs e) { } Protected void LinBtnDFile_Click (object sender, EventArgs e) { // Create a bit Array Byte [] buffer = new Byte [10240]; // Specify the path of the object to be downloaded. String filePath = @ "D: AI Zhiqiang .rar "; // Or get the file name including the extension String fileName = Path. GetFileName (filePath ); Stream fileStream = null; Try { // Open the file FileStream = new FileStream (filePath, FileMode. Open, FileAccess. Read, FileShare. Read ); Response. Clear (); // Obtain the file size Long fileSize = fileStream. Length; Long sum = 0; If (Request. Headers ["Range"]! = Null) { Response. StatusCode = 206; // an integer that indicates the HTTP output status returned to the client. The default value is 200. Sum = long. Parse (Request. Headers ["Range"]. Replace ("bytes =", ""). Replace ("-","")); } If (sum! = 0) { Response. addHeader ("Content-Range", "bytes" + sum. toString () + "-" + (long) (fileSize )). toString () + "/" + fileSize. toString ()); } // Obtain some http header information Response. AddHeader ("Content-Length", (long) (fileSize-sum). ToString ()); Response. ContentType = "application/octet-stream "; // Obtain the File Source Response. AddHeader ("Content-Disposition", "attachment; filename =" + HttpUtility. UrlEncode (Request. ContentEncoding. GetBytes (fileName ))); // Response. Flush (); FileStream. Position = sum; // you can specify the current stream Position. FileSize = fileSize-sum; // When the file size is greater than 0, it enters the loop While (fileSize> 0) { // Determine whether the client is still connected to the server If (Response. IsClientConnected) { // Obtain the total number of bytes in the buffer. Int length = fileStream. Read (buffer, 0, 10240 ); // Write data Response. OutputStream. Write (buffer, 0, length ); // Send the buffer output to the client Response. Flush (); Buffer = new Byte [10240]; FileSize = fileSize-length; } Else { // Exit the loop after the user is disconnected FileSize =-1; } } } Catch (Exception ex) { Response. Write ("Error:" + ex. Message ); } Finally { If (fileStream! = Null) { // Close the file FileStream. Close (); } Response. End (); } } }