文件下載是一個網站最基本的功能，ASP.NET網站的文件下載功能實現也很簡單，但是如果遇到大文件的下載而不做特殊處理的話，那將會出現不可預料的后果。本文就基于ASP.NET提供大文件下載的實現思路及代碼。
當我們的網站需要支持下載大文件時，如果不做控制可能會導致用戶在訪問下載頁面時發生無響應，使得瀏覽器崩潰。可以參考如下代碼來避免這個問題。
| 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970 | 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 typeResponse.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 disconnectsdataToRead = -1;}}}catch (Exception ex){// Trap the error, if any.Response.Write("Error : " + ex.Message);}finally{if (iStream != null){//Close the file.iStream.Close();}
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