我试图下载一个客户端的数据到我的本地机器(编程)，他们的web服务器非常非常慢，这导致我的WebClient对象超时。
这是我的代码:
WebClient webClient = new WebClient();
webClient.Encoding = Encoding.UTF8;
webClient.DownloadFile(downloadUrl, downloadFile);
有没有办法在这个对象上设置无限超时?如果不是，有没有人能帮我举个例子告诉我另一种方法?
该URL在浏览器中工作正常-只需要大约3分钟就能显示出来。
当前回答
在某些情况下，有必要在头文件中添加用户代理:
WebClient myWebClient = new WebClient();
myWebClient.DownloadFile(myStringWebResource, fileName);
myWebClient.Headers["User-Agent"] = "Mozilla/4.0 (Compatible; Windows NT 5.1; MSIE 6.0) (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)";
这就是我案子的解决办法。
信贷:
http://genjurosdojo.blogspot.com/2012/10/the-remote-server-returned-error-504.html
其他回答
不能让w.t otimeout代码在拔出网线时工作，它只是没有超时，移动到使用HttpWebRequest，现在做的工作。
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(downloadUrl);
request.Timeout = 10000;
request.ReadWriteTimeout = 10000;
var wresp = (HttpWebResponse)request.GetResponse();
using (Stream file = File.OpenWrite(downloadFile))
{
wresp.GetResponseStream().CopyTo(file);
}
第一个解决方案不适合我，但这里有一些代码确实适合我。
private class WebClient : System.Net.WebClient
{
public int Timeout { get; set; }
protected override WebRequest GetWebRequest(Uri uri)
{
WebRequest lWebRequest = base.GetWebRequest(uri);
lWebRequest.Timeout = Timeout;
((HttpWebRequest)lWebRequest).ReadWriteTimeout = Timeout;
return lWebRequest;
}
}
private string GetRequest(string aURL)
{
using (var lWebClient = new WebClient())
{
lWebClient.Timeout = 600 * 60 * 1000;
return lWebClient.DownloadString(aURL);
}
}
用法:
using (var client = new TimeoutWebClient(TimeSpan.FromSeconds(10)))
{
return await client.DownloadStringTaskAsync(url).ConfigureAwait(false);
}
类:
using System;
using System.Net;
namespace Utilities
{
public class TimeoutWebClient : WebClient
{
public TimeSpan Timeout { get; set; }
public TimeoutWebClient(TimeSpan timeout)
{
Timeout = timeout;
}
protected override WebRequest GetWebRequest(Uri uri)
{
var request = base.GetWebRequest(uri);
if (request == null)
{
return null;
}
var timeoutInMilliseconds = (int) Timeout.TotalMilliseconds;
request.Timeout = timeoutInMilliseconds;
if (request is HttpWebRequest httpWebRequest)
{
httpWebRequest.ReadWriteTimeout = timeoutInMilliseconds;
}
return request;
}
}
}
但我推荐一个更现代的解决方案:
using System;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
public static async Task<string> ReadGetRequestDataAsync(Uri uri, TimeSpan? timeout = null, CancellationToken cancellationToken = default)
{
using var source = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
if (timeout != null)
{
source.CancelAfter(timeout.Value);
}
using var client = new HttpClient();
using var response = await client.GetAsync(uri, source.Token).ConfigureAwait(false);
return await response.Content.ReadAsStringAsync().ConfigureAwait(false);
}
它将在超时后抛出OperationCanceledException异常。
在某些情况下，有必要在头文件中添加用户代理:
WebClient myWebClient = new WebClient();
myWebClient.DownloadFile(myStringWebResource, fileName);
myWebClient.Headers["User-Agent"] = "Mozilla/4.0 (Compatible; Windows NT 5.1; MSIE 6.0) (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)";
这就是我案子的解决办法。
信贷:
http://genjurosdojo.blogspot.com/2012/10/the-remote-server-returned-error-504.html
'CORRECTED VERSION OF LAST FUNCTION IN VISUAL BASIC BY GLENNG
Protected Overrides Function GetWebRequest(ByVal address As System.Uri) As System.Net.WebRequest
Dim w As System.Net.WebRequest = MyBase.GetWebRequest(address)
If _TimeoutMS <> 0 Then
w.Timeout = _TimeoutMS
End If
Return w '<<< NOTICE: MyBase.GetWebRequest(address) DOES NOT WORK >>>
End Function
