HTTP File Download

[thiruvasagamani]

HTTP File Download

Once the upload portion of the application is built, adding download functionality is easy. We'll start by adding a DownloadFile method and accept the local file name and download URL as parameters.
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public void DownloadFile(string localFile, string downloadUrl)

The HttpWebRequest object is created the same as before, but this time we'll set the Method to "GET" to retrieve a file from the server.
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HttpWebRequest req = (HttpWebRequest)WebRequest.Create(downloadUrl);
req.Method = "GET";

Unlike "PUT", "GET" specifies all necessary information in the URL. It therefore does not need to send any data with the request to enable write stream buffering – the request can simply be submitted by calling GetResponse. This time, we need to keep the GetResponse return value.
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HttpWebResponse resp = (HttpWebResponse) req.GetResponse();

The returned HttpWebResponse represents all information returned from the server including the status code, headers, and any returned data. The returned data (which in the case of a "GET" is the contents of the server's file specified by the URL) is accessed through the HttpWebResponse response stream.
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Stream respStream = resp.GetResponseStream();

If line-by-line access to the file is required, the stream can be read using the ReadLine method of StreamReader with each line being written to the local file using a StreamWriter.
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public void DownloadFile(string localFile, string downloadUrl)
{
  HttpWebRequest req = (HttpWebRequest)WebRequest.Create(downloadUrl);
  req.Method = "GET";

  HttpWebResponse resp = (HttpWebResponse) req.GetResponse();

  // Retrieve response stream and wrap in StreamReader
  Stream respStream = resp.GetResponseStream();
  StreamReader rdr = new StreamReader(respStream);

  // Create the local file
  StreamWriter wrtr = new StreamWriter(localFile);

  // loop through response stream reading each line
  //  and writing to the local file
  string inLine = rdr.ReadLine();
  while (inLine != null)
  {
    wrtr.WriteLine(inLine);
    inLine = rdr.ReadLine();
  }

  rdr.Close();
  wrtr.Close();
}

Just as in the case of the upload, reading the stream directly and using a FileStream to create the local file provides a more efficient download that also supports non-text files such as MP3s, bitmaps, and .NET assemblies.
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public void DownloadFileBinary(string localFile, string downloadUrl)
{
  HttpWebRequest req = (HttpWebRequest)WebRequest.Create(downloadUrl);
  req.Method = "GET";

  HttpWebResponse resp = (HttpWebResponse) req.GetResponse();

  // Retrieve response stream
  Stream respStream = resp.GetResponseStream();

  // Create local file
  FileStream wrtr = new FileStream(localFile, FileMode.Create);

  // Allocate byte buffer to hold stream contents
  byte[] inData = new byte[4096];

  // loop through response stream reading each data block
  //  and writing to the local file
  int bytesRead = respStream.Read(inData, 0, inData.Length);
  while (bytesRead > 0)
  {
    wrtr.Write(inData, 0, bytesRead);
    bytesRead = respStream.Read(inData, 0, inData.Length);
  }

  respStream.Close();
  wrtr.Close();
}

Source : MSDN

[dhoni]

this program is more useful to download thehttp file easy way