从URL路径下载文件的简单方法是什么？
答案 0 :(得分：414)
using (var client = new WebClient())
{
client.DownloadFile("http://example.com/file/song/a.mpeg", "a.mpeg");
}
答案 1 :(得分：154)
包含此命名空间
using System.Net;
下载异步并添加 ProgressBar 以在UI线程中显示下载状态
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;
}
答案 2 :(得分：68)
使用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())
{
string myStringWebResource = remoteUri + fileName;
// Download the Web resource and save it into the current filesystem folder.
myWebClient.DownloadFile(myStringWebResource, fileName);
}
答案 3 :(得分：40)
using System.Net;
WebClient webClient = new WebClient();
webClient.DownloadFile("http://mysite.com/myfile.txt", @"c:\myfile.txt");
答案 4 :(得分：17)
在将状态打印到控制台时完成下载文件的课程。
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);
}
}
<强>用法：
static void Main(string[] args)
{
var success = FileDownloader.DownloadFile(fileUrl, fullPathWhereToSave, timeoutInMilliSec);
Console.WriteLine("Done - success: " + success);
Console.ReadLine();
}
答案 5 :(得分：9)
您也可以在WebClient类中使用DownloadFileAsync方法。它将具有指定URI的资源下载到本地文件。此方法也不会阻止调用线程。
样品：
webClient.DownloadFileAsync(new Uri("http://www.example.com/file/test.jpg"), "test.jpg");
有关详情：
http://csharpexamples.com/download-files-synchronous-asynchronous-url-c/
答案 6 :(得分：7)
尝试使用：
private void downloadFile(string url)
{
string file = System.IO.Path.GetFileName(url);
WebClient cln = new WebClient();
cln.DownloadFile(url, file);
}
答案 7 :(得分：6)
使用GetIsNetworkAvailable()检查网络连接，以避免在未连接到网络时创建空文件。
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");
}
}
答案 8 :(得分：2)
下面的代码包含原始名称为
的下载文件的逻辑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);
}
答案 9 :(得分：0)
根据我的研究，我发现WebClient.DownloadFileAsync是下载文件的最佳方法。它在System.Net名称空间中可用，并且还支持.net核心。
这是下载文件的示例代码。
using System;
using System.IO;
using System.Net;
using System.ComponentModel;
public class Program
{
public static void Main()
{
new Program().Download("ftp://localhost/test.zip");
}
public void Download(string remoteUri)
{
string FilePath = Directory.GetCurrentDirectory() + "/tepdownload/" + Path.GetFileName(remoteUri); // path where download file to be saved, with filename, here I have taken file name from supplied remote url
using (WebClient client = new WebClient())
{
try
{
if (!Directory.Exists("tepdownload"))
{
Directory.CreateDirectory("tepdownload");
}
Uri uri = new Uri(remoteUri);
//password username of your file server eg. ftp username and password
client.Credentials = new NetworkCredential("username", "password");
//delegate method, which will be called after file download has been complete.
client.DownloadFileCompleted += new AsyncCompletedEventHandler(Extract);
//delegate method for progress notification handler.
client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(ProgessChanged);
// uri is the remote url where filed needs to be downloaded, and FilePath is the location where file to be saved
client.DownloadFileAsync(uri, FilePath);
}
catch (Exception)
{
throw;
}
}
}
public void Extract(object sender, AsyncCompletedEventArgs e)
{
Console.WriteLine("File has been downloaded.");
}
public void ProgessChanged(object sender, DownloadProgressChangedEventArgs e)
{
Console.WriteLine($"Download status: {e.ProgressPercentage}%.");
}
}
带有以上代码的文件将下载到项目目录的tepdownload文件夹中。请阅读代码中的注释以了解上述代码的作用。
答案 10 :(得分：0)
如果您需要设置 Headers 和 Cookies 来下载文件，您需要做一些稍微不同的事情。这是一个示例...
// Pass in the HTTPGET URL, Full Path w/Filename, and a populated Cookie Container (optional)
private async Task DownloadFileRequiringHeadersAndCookies(string getUrl, string fullPath, CookieContainer cookieContainer, CancellationToken cancellationToken)
{
cookieContainer ??= new CookieContainer(); // TODO: FILL ME AND PASS ME IN
using (var handler = new HttpClientHandler()
{
UseCookies = true,
CookieContainer = cookieContainer, // This will, both, use the cookies passed in, and update/create cookies from the response
ServerCertificateCustomValidationCallback = (message, cert, chain, errors) => true, // use only if it gets angry about the SSL endpoints
AllowAutoRedirect = true,
})
{
using (var client = new HttpClient(handler))
{
SetHeaders(client);
using (var response = await client.GetAsync(getUrl, cancellationToken))
{
if (response.IsSuccessStatusCode)
{
var bytes = await response.Content.ReadAsByteArrayAsync(cancellationToken);
await File.WriteAllBytesAsync(fullPath, bytes, cancellationToken); // This overwrites the file
}
else
{
// TODO: HANDLE ME
throw new FileNotFoundException();
}
}
}
}
}
而且，要添加您需要的标题...
private void SetHeaders(HttpClient client)
{
// TODO: SET ME
client.DefaultRequestHeaders.Connection.Add("keep-alive");
client.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) ...");
client.DefaultRequestHeaders.Add("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9, ...");
client.DefaultRequestHeaders.AcceptEncoding.Add(new StringWithQualityHeaderValue("gzip"));
client.DefaultRequestHeaders.AcceptEncoding.Add(new StringWithQualityHeaderValue("deflate"));
client.DefaultRequestHeaders.AcceptLanguage.Add(new StringWithQualityHeaderValue("en-US"));
client.DefaultRequestHeaders.AcceptLanguage.Add(new StringWithQualityHeaderValue("en", .9));
...
}
旁白：您可以通过以下方式填充 CookieContainer：
答案 11 :(得分：0)
WebClient 已过时
如果你想下载到一个文件，避免使用 ResponseHeadersRead 像这样先读到内存：
static public async Task HttpDownloadFileAsync(HttpClient httpClient, string url, string fileToWriteTo) {
using HttpResponseMessage response = await httpClient.GetAsync(url, HttpCompletionOption.ResponseHeadersRead);
using Stream streamToReadFrom = await response.Content.ReadAsStreamAsync();
using Stream streamToWriteTo = File.Open(fileToWriteTo, FileMode.Create);
await streamToReadFrom.CopyToAsync(streamToWriteTo);
}
答案 12 :(得分：0)
static void Main(string[] args)
{
DownloadFileAsync().GetAwaiter();
Console.WriteLine("File was downloaded");
Console.Read();
}
private static async Task DownloadFileAsync()
{
WebClient client = new WebClient();
await client.DownloadFileTaskAsync(new Uri("http://somesite.com/myfile.txt"), "mytxtFile.txt");
}
答案 13 :(得分：-11)
您可以转换为字节流对象并将其存储为SQL Server中的varbinary（MAX）BLOB，而不是将其下载到本地文件。
鉴于您的表格如下：
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();