How to use HttpWebRequest in .NET

Internet applications can be classified broadly into two kinds: client applications that request information, and server applications that respond to information requests from clients. The classic Internet client-server application is the World Wide Web, where people use browsers to access documents and other data stored on Web servers worldwide. 

The System.Net.WebClient class provides functionality to upload data to or download data from the Internet or intranet or a local file system. The WebClient class provides many ways to download and upload data. The following table describes WebClient class methods and properties briefly.

Code :

        public class ClsDownloadFile

        {

            // The stream of data retrieved from the web server

            private Stream strResponse;

            // The stream of data that we write to the harddrive

            private Stream strLocal;

            // The request to the web server for file information

            private HttpWebRequest webRequest;

            // The response from the web server containing information about the file

            private HttpWebResponse webResponse;

            public void DownloadFile(object startPoint, string DestinationPath, String SourcePath)

            {

                try

                {

                    // Put the object argument into an int variable

                    int startPointInt = Convert.ToInt32(startPoint);

                    // Create a request to the file we are downloading

                    webRequest = (HttpWebRequest)WebRequest.Create(SourcePath);

                    // Set the starting point of the request

                    webRequest.AddRange(startPointInt);

                    // Set default authentication for retrieving the file

                    webRequest.Credentials = CredentialCache.DefaultCredentials;

                    // Retrieve the response from the server

                    webResponse = (HttpWebResponse)webRequest.GetResponse();

                    // Ask the server for the file size and store it

                    Int64 fileSize = webResponse.ContentLength;

                    // Open the URL for download

                    strResponse = webResponse.GetResponseStream();

                    // Create a new file stream where we will be saving the data (local drive)

                    if (startPointInt == 0)

                    {

                        strLocal = new FileStream(DestinationPath, FileMode.Create, FileAccess.Write, FileShare.None);

                    }

                    else

                    {

                        strLocal = new FileStream(DestinationPath, FileMode.Append, FileAccess.Write, FileShare.None);

                    }

                    // It will store the current number of bytes we retrieved from the server

                    int bytesSize = 0;

                    // A buffer for storing and writing the data retrieved from the server

                    byte[] downBuffer = new byte[2048];

                    // Loop through the buffer until the buffer is empty

                    while ((bytesSize = strResponse.Read(downBuffer, 0, downBuffer.Length)) > 0)

                    {

                        // Write the data from the buffer to the local hard drive

                        strLocal.Write(downBuffer, 0, bytesSize);

                    }

                }

                finally

                {

                    // When the above code has ended, close the streams

                    strResponse.Close();

                    strLocal.Close();

                }

            }

        }

Call Function Using blow code

ClsDownloadFile _ObjDownload = new ClsDownloadFile();

_ObjDownload.DownloadFile("0", @"D:\destination.zip", @"E:\Source.zip");