这是代码:
HttpWebRequest request;
int currentIndex = 0;
void fileDownloadRadar(string uri, string fileName)
{
if (splash != null)
{
if (!splash.IsDisposed)
splash.UpdateProgressBar(0);
}
/*_request = WebRequest.Create(uri) as HttpWebRequest;
_request.CookieContainer = new CookieContainer();
_request.AllowAutoRedirect = true;
_responseAsyncResult = _request.BeginGetResponse(ResponseCallback, null);*/
request = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(uri);
request.CookieContainer = new CookieContainer();
request.AllowAutoRedirect = true;
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
long contentLength = response.ContentLength;
if (response.ContentType == "")
{
Logger.Write("ContentType is Empty download was not fine !!!!!");
}
if ((response.StatusCode == HttpStatusCode.OK ||
response.StatusCode == HttpStatusCode.Moved ||
response.StatusCode == HttpStatusCode.Redirect) &&
response.ContentType.StartsWith("image", StringComparison.OrdinalIgnoreCase))
{
Logger.Write("ContentType is not empty meaning download is fine");
using (Stream inputStream = response.GetResponseStream())
using (Stream outputStream = File.OpenWrite(fileName))
{
byte[] buffer = new byte[4096];
int bytesRead;
do
{
bytesRead = inputStream.Read(buffer, 0, buffer.Length);
currentIndex += bytesRead;
double percentage = (double)currentIndex / contentLength;
if (splash != null)
{
if (!splash.IsDisposed)
splash.UpdateProgressBar((int)(percentage * 100));
}
outputStream.Write(buffer, 0, bytesRead);
} while (bytesRead != 0);
if (splash != null)
{
if (!splash.IsDisposed)
{
splash.UpdateProgressBar(100);
}
}
}
}
else
{
timer1.Stop();
timer3.Start();
}
if (splash == null)
FinishWebRequest();
}
异常在线:
bytesRead = inputStream.Read(buffer, 0, buffer.Length);
异常是:WebException
操作超时
我看到异常发生时变量 bytesRead 的值为 1360 缓冲区值为 4096
System.Net.WebException occurred
HResult=-2146233079
Message=The operation has timed out.
Source=System
StackTrace:
at System.Net.ConnectStream.Read(Byte[] buffer, Int32 offset, Int32 size)
at mws.Form1.fileDownloadRadar(String uri, String fileName) in d:\C-Sharp\Download File\Downloading-File-Project-Version-012\Downloading File\Form1.cs:line 914
InnerException:
第 914 行是:
bytesRead = inputStream.Read(buffer, 0, buffer.Length);
也许我应该把 try and catch 放在某个地方？
我的代码正在下载一个文件，然后计时器开始运行，当计时器计时 5 分钟时，它会再次下载同一个文件，依此类推，我会每 5 分钟不间断地调用此方法来下载文件。
编辑这是我根据答案更改后的代码:
HttpWebRequest request;
int currentIndex = 0;
void fileDownloadRadar(string uri, string fileName)
{
if (splash != null)
{
if (!splash.IsDisposed)
splash.UpdateProgressBar(0);
}
try
{
request = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(uri);
request.Timeout = 10000;
request.CookieContainer = new CookieContainer();
request.AllowAutoRedirect = true;
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
long contentLength = response.ContentLength;
if (response.ContentType == "")
{
Logger.Write("ContentType is Empty download was not fine !!!!!");
}
if ((response.StatusCode == HttpStatusCode.OK ||
response.StatusCode == HttpStatusCode.Moved ||
response.StatusCode == HttpStatusCode.Redirect) &&
response.ContentType.StartsWith("image", StringComparison.OrdinalIgnoreCase))
{
Logger.Write("ContentType is not empty meaning download is fine");
using (Stream inputStream = response.GetResponseStream())
using (Stream outputStream = File.OpenWrite(fileName))
{
byte[] buffer = new byte[4096];
int bytesRead;
do
{
bytesRead = inputStream.Read(buffer, 0, buffer.Length);
currentIndex += bytesRead;
double percentage = (double)currentIndex / contentLength;
if (splash != null)
{
if (!splash.IsDisposed)
splash.UpdateProgressBar((int)(percentage * 100));
}
outputStream.Write(buffer, 0, bytesRead);
} while (bytesRead != 0);
if (splash != null)
{
if (!splash.IsDisposed)
{
splash.UpdateProgressBar(100);
}
}
}
}
else
{
timer1.Stop();
timer3.Start();
}
if (splash == null)
FinishWebRequest();
}
}
catch (WebException ex)
{
if (ex.Status == WebExceptionStatus.Timeout)
{
Logger.Write(ex.Status.ToString());
}
}
}
但是在它正常工作了大概一个小时左右并下载了几次文件之后，我又遇到了异常超时:
操作超时
这次上线:
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
异常信息:
System.Net.WebException occurred
HResult=-2146233079
Message=The operation has timed out
Source=System
StackTrace:
at System.Net.HttpWebRequest.GetResponse()
at mws.Form1.fileDownloadRadar(String uri, String fileName) in d:\C-Sharp\Download File\Downloading-File-Project-Version-012\Downloading File\Form1.cs:line 899
InnerException:
我更改了响应并使用 using 还添加了:request.Timeout = 10000； 并添加了 try and catch。
请您参考如下方法:
您看到的超时是由 ServicePointManager 引起的- 管理 ServicePoint 集合的类为 HTTP 连接提供连接管理的对象。
简而言之，无论何时创建请求和响应，重要的是调用响应对象的 Close() 方法。否则，它将阻止 ServicePoint 对象中的任何连接被释放，因此在某些时候，在您发出了临界数量的请求后，无法处理其他请求，您将遇到超时。
有关更深入的信息，请查看这篇文章:http://blogs.msdn.com/b/jpsanders/archive/2009/05/20/understanding-maxservicepointidletime-and-defaultconnectionlimit.aspx
HttpWebRequest req = CreateRequest();
HttpWebResponse res = req.GetResponse() as HttpWebResponse;
...
res.Close(); //you should always close the response
编辑:
正如@Kevin 在评论中所说，另一种解决方案是将响应包装在 using 语句中，这将自动关闭连接:
using(HttpWebResponse res = req.GetResponse() as HttpWebResponse)
{
...
}
