Wie lade ich eine Datei von einer URL in C # herunter?

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

InformationsquelleAutor der Antwort Raj Kumar

Verwenden 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);        
}

InformationsquelleAutor der Antwort vbroto

Komplette Klasse um eine Datei herunterzuladen, während Sie den Druck-status in die Konsole.

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);
    }
}

Verwendung:

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

InformationsquelleAutor der Antwort Jonas_Hess

Überprüfen Sie die Netzwerkverbindung mit GetIsNetworkAvailable() um zu vermeiden, leere Dateien, wenn Sie nicht mit einem Netzwerk verbunden.

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");
    }                  
}

InformationsquelleAutor der Antwort haZya

Müssen Sie wissen, den status und die Aktualisierung der ProgressBar während das herunterladen von Dateien oder die Verwendung von Anmeldeinformationen, bevor Sie die Anfrage.

Ist es hier, ein Beispiel, das deckt diese Optionen. Lambda-notation und String-interpolation verwendet wurde:

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");
}

InformationsquelleAutor der Antwort Kreshnik

Statt dem herunterladen dieser auf eine lokale Datei, die Sie konvertieren können, um ein byte-stream-Objekt und speichern Sie als varbinary(MAX) - Blobs in SQL Server.

Gegeben, dass Ihre Tabelle sieht wie folgt aus:

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();

InformationsquelleAutor der Antwort John H