错误“此流不支持查找操作”。在C#中
我正在尝试使用 byte
流从网址中获取图片。但是我收到此错误消息:
I'm trying to get an image from an url using a byte
stream. But i get this error message:
此流不支持搜索操作。
This stream does not support seek operations.
这是我的代码:
byte[] b;
HttpWebRequest myReq = (HttpWebRequest)WebRequest.Create(url);
WebResponse myResp = myReq.GetResponse();
Stream stream = myResp.GetResponseStream();
int i;
using (BinaryReader br = new BinaryReader(stream))
{
i = (int)(stream.Length);
b = br.ReadBytes(i); // (500000);
}
myResp.Close();
return b;
我在做什么错人?
您可能想要这样的东西。要么检查长度失败,要么BinaryReader在后台进行查找。
You probably want something like this. Either checking the length fails, or the BinaryReader is doing seeks behind the scenes.
HttpWebRequest myReq = (HttpWebRequest)WebRequest.Create(url);
WebResponse myResp = myReq.GetResponse();
byte[] b = null;
using( Stream stream = myResp.GetResponseStream() )
using( MemoryStream ms = new MemoryStream() )
{
int count = 0;
do
{
byte[] buf = new byte[1024];
count = stream.Read(buf, 0, 1024);
ms.Write(buf, 0, count);
} while(stream.CanRead && count > 0);
b = ms.ToArray();
}
编辑:
我使用反射器检查了,这是对stream.Length的调用失败。 GetResponseStream返回一个ConnectStream,并且该类的Length属性引发您看到的异常。正如其他张贴者所提到的那样,您无法可靠地获取HTTP响应的长度,所以这是有道理的。
I checked using reflector, and it is the call to stream.Length that fails. GetResponseStream returns a ConnectStream, and the Length property on that class throws the exception that you saw. As other posters mentioned, you cannot reliably get the length of a HTTP response, so that makes sense.