从URL路径下载文件的简单方法是什么?
当前回答
WebRequest, WebClient和ServicePoint在。net 6(源代码- 2021年11月)中已经过时。
使用System.Net.Http.HttpClient类代替:
using (var client = new HttpClient())
{
using (var s = client.GetStreamAsync("https://via.placeholder.com/150"))
{
using (var fs = new FileStream("localfile.jpg", FileMode.OpenOrCreate))
{
s.Result.CopyTo(fs);
}
}
}
相同代码的异步版本:
using var client = new HttpClient();
using var s = await client.GetStreamAsync("https://via.placeholder.com/150");
using var fs = new FileStream("localfile.jpg", FileMode.OpenOrCreate);
await s.CopyToAsync(fs);
其他回答
您可能需要在文件下载期间了解状态并更新ProgressBar,或者在发出请求之前使用凭据。
下面是一个包含这些选项的示例。Lambda符号和字符串插值已被使用:
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");
}
这是我的解决方案,效果很好:
public static void DownloadFile(string url, string pathToSaveFile)
{
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
// or: ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;
using (WebDownload client = new WebDownload())
{
client.Headers["User-Agent"] = "User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36";
client.DownloadFile(new Uri(url), pathToSaveFile);
}
}
public class WebDownload : WebClient
{
protected override WebRequest GetWebRequest(Uri address)
{
HttpWebRequest request = (HttpWebRequest)base.GetWebRequest(address);
if (request != null)
{
request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
}
return request;
}
}
using (var client = new WebClient())
{
client.DownloadFile("http://example.com/file/song/a.mpeg", "a.mpeg");
}
包括这个命名空间
using System.Net;
异步下载,并在UI线程本身中放置一个ProgressBar来显示下载的状态
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;
}
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");
}
}
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