desde - descargar archivo c# windows form

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

Question

¿Cuál es una forma sencilla de descargar un archivo desde una ruta URL?

Answer 1

El siguiente código contiene la lógica para descargar el archivo 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 2

En lugar de descargarlo en un archivo local, puede convertirlo en un objeto de flujo de bytes y almacenarlo como un BLOB varbinary (MAX) en SQL Server.

Dado que su mesa se ve como:

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 3

Es posible que deba conocer el estado y actualizar una Barra de progreso durante la descarga del archivo o usar las credenciales antes de realizar la solicitud.

Aquí está, un ejemplo que cubre estas opciones. Se ha utilizado la notación lambda y la interpolación de cadenas :

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 4

Incluir este espacio de nombres

using System.Net;

Descargue de forma asíncrona y coloque una barra de progreso para mostrar el estado de la descarga dentro de la interfaz de usuario.

private void BtnDownload_Click(object sender, RoutedEventArgs e)
{
using (WebClient wc = new WebClient())
{
wc.DownloadProgressChanged += wc_DownloadProgressChanged;
wc.DownloadFileAsync (
// Param1 = Link of file
new System.Uri("http://www.sayka.com/downloads/front_view.jpg"),
// Param2 = Path to save
"D://Images//front_view.jpg"
);
}
}
// Event to track the progress
void wc_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
progressBar.Value = e.ProgressPercentage;
}

Answer 5

Intenta usar esto:

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

Answer 6

También puede usar el método DownloadFileAsync en la clase de WebClient. Descarga a un archivo local el recurso con el URI especificado. También 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 7

Utilice 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 8

Verifique si hay una conexión de red usando GetIsNetworkAvailable() para evitar crear archivos vacíos cuando no esté 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 9

Clase completa para descargar un archivo mientras se imprime el estado en 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 10

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

Answer 11

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