Recipe16.4.Downloading Data from a Server

Recipe 16.4. Downloading Data from a Server

Problem

You need to download data from a location specified by a URL; this data can be either an array of bytes or a file.

Solution

Use the WebClient.DownloadData method to download data from a URL:

 string uri = "http://localhost/mysite/index.aspx"; // Make a client using (WebClient client = new WebClient()) {     // Get the contents of the file     Console.WriteLine("Downloading {0} " + uri);     // Download the page and store the bytes     byte[] bytes;     try     {          bytes = client.DownloadData(uri);      }     catch (WebException we)     {         Console.WriteLine(we.ToString());         return;     }     // Write the content out     string page = Encoding.ASCII.GetString(bytes);     Console.WriteLine(page); }

This will produce the following output:

 Downloading {0} http://localhost/mysite/index.aspx <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" > <HTML>     <HEAD>          <title>WebForm1</title>          <meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">          <meta name="CODE_LANGUAGE" Content="C#">          <meta name="vs_defaultClientScript" content="JavaScript">          <meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">     </HEAD>     <body MS_POSITIONING="GridLayout">         <form name="Form1" method="post" action="index.aspx" > <input type="hidden" name="__VIEWSTATE" value="dDwyMDQwNjUzNDY2Ozs+kS9hguYm9369sybDqmIow0AvxBg=" />                <span  style="Z-INDEX: 101; LEFT: 142px; POSITION: absolute;  TOP: 164px">This is index.aspx!</span>          </form>      </body>  </HTML>

You can also download data to a file using DownloadFile:

 // Make a client using (WebClient client = new WebClient()) {     // Go get the file     Console.WriteLine("Retrieving file from {0}…\r\n", uri);     // Get file and put it in a temp file     string tempFile = Path.GetTempFileName( );     client.DownloadFile(uri,tempFile);     Console.WriteLine("Downloaded {0} to {1}",uri,tempFile); }

This will produce the following output:

 Retrieving file from http://localhost/mysite/index.aspx… Downloaded http://localhost/mysite/index.aspx to C:\Documents and Settings\[user]\  Local Settings\Temp\tmp17C.tmp

Discussion

WebClient simplifies downloading of files and bytes in files, as these are common tasks when dealing with the Web. The more traditional stream-based method for downloading can also be accessed via the OpenRead method on the WebClient.