我是否需要将流（C#）重置回开始？
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Do I need to reset a stream(C#) back to the start?
提问by chobo2
I don't know too much about streams in C#. Right now I have a stream that I put into a stream reader and read it. Later on in some other method I need to read the stream(same stream object) but this time I get this error
我不太了解 C# 中的流。现在我有一个流，我放入流阅读器并阅读它。稍后在其他一些方法中，我需要读取流（相同的流对象），但这次我收到此错误
System.ArgumentException was unhandled by user code
Message="Stream was not readable."
Source="mscorlib"
StackTrace:
at System.IO.StreamReader..ctor(Stream stream, Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize)
at System.IO.StreamReader..ctor(Stream stream)
at ExtractTitle(Stream file) in :line 33
at GrabWebPage(String webPath) in :line 62
at lambda_method(ExecutionScope , ControllerBase , Object[] )
at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClassa.<InvokeActionMethodWithFilters>b__7()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
InnerException:
So I am thinking maybe by reading the stream it goes to the end. Then when I try to read it again it is at the end of the stream and thats why I am getting this error.
所以我想也许通过阅读它到达最后的流。然后，当我再次尝试读取它时，它位于流的末尾，这就是我收到此错误的原因。
So can anyone shed some light on this?
那么任何人都可以对此有所了解吗？
Thanks
谢谢
采纳答案by chobo2
When you read a stream to the end, specifically with StreamReader's ReadToEndmethod, you have to Seekit back to the beginning. This can be done like so:
当您将流读到最后时，特别是使用StreamReader'sReadToEnd方法时，您必须将Seek其返回到开头。这可以像这样完成：
StreamReader sr = new StreamReader(stream);
sr.ReadToEnd();
stream.Seek(0, SeekOrigin.Begin); //StreamReader doesn't have the Seek method, stream does.
sr.ReadToEnd(); // This now works
回答by Michael Petrotta
Your conclusion is correct; once you've reached the end of your stream, you won't be able to read more data until you've reset your position within the stream:
你的结论是正确的；一旦到达流的末尾，您将无法读取更多数据，直到您在流中重置位置：
myStream.Position = 0;
This is equivalent to seeking back to the beginning. Note that your stream must support seeking for this to work; not all streams do. You can check this with the CanSeekproperty.
这相当于找回原点。请注意，您的流必须支持寻求此功能；并非所有流都可以。您可以向CanSeek酒店确认这一点。
回答by Glaucio BP
Use BaseStreamfor StreamReader:
使用BaseStream为StreamReader：
StreamReader sr = new StreamReader(pFileStream);
sr.BaseStream.Seek(0, SeekOrigin.Begin);
