¿Cómo descargar un archivo de una URL en C#?

Question

¿Qué es una forma simple de descargar un archivo desde una ruta URL?

Answer 1

Uso System.Net.WebClient.DownloadFile:

string remoteUri = "http://www.contoso.com/library/homepage/images/"; 
string fileName = "ms-banner.gif", myStringWebResource = null; 

// Create a new WebClient instance. 
using (WebClient myWebClient = new WebClient()) 
{ 
    myStringWebResource = remoteUri + fileName; 
    // Download the Web resource and save it into the current filesystem folder. 
    myWebClient.DownloadFile(myStringWebResource, fileName);   
} 

Answer 2

using (var client = new WebClient()) 
{ 
    client.DownloadFile("http://example.com/file/song/a.mpeg", "a.mpeg"); 
} 

Answer 3

using System.Net; 

WebClient webClient = new WebClient(); 
webClient.DownloadFile("http://mysite.com/myfile.txt", @"c:\myfile.txt"); 

Answer 4

También puede utilizar el método DownloadFileAsync en la clase de cliente Web. Descarga a un archivo local el recurso con el URI especificado. Además, este método no bloquea el hilo de llamada.

muestra:

webClient.DownloadFileAsync(new Uri("http://www.example.com/file/test.jpg"), "test.jpg"); 

Para más información:

http://csharpexamples.com/download-files-synchronous-asynchronous-url-c/

Answer 5

Incluir este espacio de nombres

using System.Net; 

Descargar asincrónica y poner un ProgressBar para mostrar el estado de la descarga dentro de la interfaz de usuario propio hilo

private void BtnDownload_Click(object sender, RoutedEventArgs e) 
{ 
    using (WebClient wc = new WebClient()) 
    { 
     wc.DownloadProgressChanged += wc_DownloadProgressChanged; 
     wc.DownloadFileAsync(new System.Uri("http://www.sayka.in/downloads/front_view.jpg"), 
     "D:\\Images\\front_view.jpg"); 
    } 
} 

void wc_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e) 
{ 
    progressBar.Value = e.ProgressPercentage; 
} 

Answer 6

Compruebe si hay una conexión de red utilizando GetIsNetworkAvailable() para evitar crear archivos vacíos cuando no está conectado a una red.

if (System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable()) 
{ 
    using (System.Net.WebClient client = new System.Net.WebClient()) 
    {       
      client.DownloadFileAsync(new Uri("http://www.examplesite.com/test.txt"), 
      "D:\\test.txt"); 
    }     
} 

Answer 7

clase completa para descargar un archivo mientras se imprime el estado a la consola.

using System; 
using System.ComponentModel; 
using System.IO; 
using System.Net; 
using System.Threading; 

class FileDownloader 
{ 
    private readonly string _url; 
    private readonly string _fullPathWhereToSave; 
    private bool _result = false; 
    private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(0); 

    public FileDownloader(string url, string fullPathWhereToSave) 
    { 
     if (string.IsNullOrEmpty(url)) throw new ArgumentNullException("url"); 
     if (string.IsNullOrEmpty(fullPathWhereToSave)) throw new ArgumentNullException("fullPathWhereToSave"); 

     this._url = url; 
     this._fullPathWhereToSave = fullPathWhereToSave; 
    } 

    public bool StartDownload(int timeout) 
    { 
     try 
     { 
      System.IO.Directory.CreateDirectory(Path.GetDirectoryName(_fullPathWhereToSave)); 

      if (File.Exists(_fullPathWhereToSave)) 
      { 
       File.Delete(_fullPathWhereToSave); 
      } 
      using (WebClient client = new WebClient()) 
      { 
       var ur = new Uri(_url); 
       // client.Credentials = new NetworkCredential("username", "password"); 
       client.DownloadProgressChanged += WebClientDownloadProgressChanged; 
       client.DownloadFileCompleted += WebClientDownloadCompleted; 
       Console.WriteLine(@"Downloading file:"); 
       client.DownloadFileAsync(ur, _fullPathWhereToSave); 
       _semaphore.Wait(timeout); 
       return _result && File.Exists(_fullPathWhereToSave); 
      } 
     } 
     catch (Exception e) 
     { 
      Console.WriteLine("Was not able to download file!"); 
      Console.Write(e); 
      return false; 
     } 
     finally 
     { 
      this._semaphore.Dispose(); 
     } 
    } 

    private void WebClientDownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e) 
    { 
     Console.Write("\r  --> {0}%.", e.ProgressPercentage); 
    } 

    private void WebClientDownloadCompleted(object sender, AsyncCompletedEventArgs args) 
    { 
     _result = !args.Cancelled; 
     if (!_result) 
     { 
      Console.Write(args.Error.ToString()); 
     } 
     Console.WriteLine(Environment.NewLine + "Download finished!"); 
     _semaphore.Release(); 
    } 

    public static bool DownloadFile(string url, string fullPathWhereToSave, int timeoutInMilliSec) 
    { 
     return new FileDownloader(url, fullPathWhereToSave).StartDownload(timeoutInMilliSec); 
    } 
} 

Uso:

static void Main(string[] args) 
{ 
    var success = FileDownloader.DownloadFile(fileUrl, fullPathWhereToSave, timeoutInMilliSec); 
    Console.WriteLine("Done - success: " + success); 
    Console.ReadLine(); 
} 

Answer 8

En lugar de descargar a un archivo local, puede convertir a un objeto flujo de bytes y la tienda como un BLOB varbinary (max) en SQL Server.

Dado que la tabla se ve así:

CREATE TABLE [dbo].[Documents](
    [DocumentId] [int] IDENTITY(1,1) NOT NULL, 
    [DocumentTypeId] [int] NOT NULL, 
    [UploadedByMemberId] [int] NOT NULL, 
    [DocumentTitle] [nvarchar](200) NOT NULL, 
    [DocumentDescription] [nvarchar](2000) NULL, 
    [FileName] [nvarchar](200) NOT NULL, 
    [DateUploaded] [datetime] NOT NULL, 
    [ApprovedForUsers] [bit] NOT NULL, 
    [ApprovedByMemberId] [int] NOT NULL, 
    [ApprovedDate] [datetime] NULL, 
    [DocBLOB] [varbinary](max) NOT NULL, 
CONSTRAINT [PK_Documents] PRIMARY KEY CLUSTERED 
(
    [DocumentId] ASC 
) 

      SqlParameter Title = new SqlParameter("@Title", SqlDbType.VarChar); 
      SqlParameter FileName = new SqlParameter("@FileName", SqlDbType.VarChar); 
      SqlParameter DateFileUploaded = new SqlParameter("@DateUploaded", SqlDbType.VarChar); 
      SqlParameter DocBLOB = new SqlParameter("@DocBLOB", SqlDbType.VarBinary); 
      command.Parameters.Add(Title); 
      command.Parameters.Add(FileName); 
      command.Parameters.Add(DateFileUploaded); 
      command.Parameters.Add(DocBLOB); 
         myStringWebResource = remoteUri + dataReader["FileName"].ToString(); 
         imgdownload = myWebClient.DownloadData(myStringWebResource); 
         querySQL = @"INSERT INTO Documents(DocumentTypeId, UploadedByMemberId, DocumentTitle, DocumentDescription, FileName, DateUploaded, ApprovedForUsers, ApprovedByMemberId, ApprovedDate, DocBLOB) VALUES(1, 0, @Title, '', @FileName, @DateUploaded, 1, 0, GETDATE(), @DocBLOB);"; 

         Title.Value = dataReader["Title"].ToString().Replace("'", "''").Replace("\"", ""); 
         FileName.Value = dataReader["FileName"].ToString().Replace("'", "''").Replace("\"", ""); 
         DateFileUploaded.Value = dataReader["DateUploaded"].ToString(); 
         DocBLOB.Value = imgdownload; 

         command.CommandText = querySQL; 
         command.ExecuteNonQuery(); 

Answer 9

Es posible que necesite conocer el estado y actualizar un ProgressBar durante la descarga de archivos o utilizar credenciales antes de realizar la consulta.

Aquí está, un ejemplo que cubre estas opciones. Lambda notación y cadena de interpolación se ha utilizado:

using System.Net; 
// ... 

using (WebClient client = new WebClient()) { 
    Uri ur = new Uri("http://remotehost.do/images/img.jpg"); 

    //client.Credentials = new NetworkCredential("username", "password"); 
    String credentials = Convert.ToBase64String(Encoding.ASCII.GetBytes("Username" + ":" + "MyNewPassword")); 
    client.Headers[HttpRequestHeader.Authorization] = $"Basic {credentials}"; 

    client.DownloadProgressChanged += (o, e) => 
    { 
     Console.WriteLine($"Download status: {e.ProgressPercentage}%."); 

     // updating the UI 
     Dispatcher.Invoke(() => { 
      progressBar.Value = e.ProgressPercentage; 
     }); 
    }; 

    client.DownloadDataCompleted += (o, e) => 
    { 
     Console.WriteLine("Download finished!"); 
    }; 

    client.DownloadFileAsync(ur, @"C:\path\newImage.jpg"); 
} 

Answer 10

A continuación código contienen la lógica de descarga de archivos con el nombre original

private string DownloadFile(string url) 
    { 

     HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url); 
     string filename = ""; 
     string destinationpath = Environment; 
     if (!Directory.Exists(destinationpath)) 
     { 
      Directory.CreateDirectory(destinationpath); 
     } 
     using (HttpWebResponse response = (HttpWebResponse)request.GetResponseAsync().Result) 
     { 
      string path = response.Headers["Content-Disposition"]; 
      if (string.IsNullOrWhiteSpace(path)) 
      { 
       var uri = new Uri(url); 
       filename = Path.GetFileName(uri.LocalPath); 
      } 
      else 
      { 
       ContentDisposition contentDisposition = new ContentDisposition(path); 
       filename = contentDisposition.FileName; 

      } 

      var responseStream = response.GetResponseStream(); 
      using (var fileStream = File.Create(System.IO.Path.Combine(destinationpath, filename))) 
      { 
       responseStream.CopyTo(fileStream); 
      } 
     } 

     return Path.Combine(destinationpath, filename); 
    } 

Answer 11

Trate de usar esto:

private void downloadFile(string url) 
{ 
    string file = System.IO.Path.GetFileName(url); 
    WebClient cln = new WebClient(); 
    cln.DownloadFile(url, file); 
}