使用HttpWebRequest,我可以调用XDocument.Save()来写直接到请求流:
XDocument doc = ...;
var request = (HttpWebRequest)WebCreate.Create(uri);
request.method = "POST";
Stream requestStream = request.GetRequestStream();
doc.Save(requestStream);
是否可以用
HttpClient
做同样的事情? ?直接的方法是XDocument doc = ...;
Stream stream = new MemoryStream();
doc.Save(stream);
var content = new System.Net.Http.StreamContent(stream);
var client = new HttpClient();
client.Post(uri, content);
但这会创建
XDocument
的另一个副本在 MemoryStream
.
最佳答案
XDocument.Save()
期待 Stream
可以写入。 StreamContent
期望可以读取的流。因此,您可以使用两个 Stream
s,其中一个充当另一个的转发器。我认为框架中不存在这种类型,但是您可以自己编写一个:
class ForwardingStream
{
private readonly ReaderStream m_reader;
private readonly WriterStream m_writer;
public ForwardingStream()
{
// bounded, so that writing too much data blocks
var buffers = new BlockingCollection<byte[]>(10);
m_reader = new ReaderStream(buffers);
m_writer = new WriterStream(buffers);
}
private class ReaderStream : Stream
{
private readonly BlockingCollection<byte[]> m_buffers;
private byte[] m_currentBuffer;
private int m_readFromCurrent;
public ReaderStream(BlockingCollection<byte[]> buffers)
{
m_buffers = buffers;
}
public override void Flush()
{}
public override long Seek(long offset, SeekOrigin origin)
{
throw new NotSupportedException();
}
public override void SetLength(long value)
{
throw new NotSupportedException();
}
public override int Read(byte[] buffer, int offset, int count)
{
if (m_currentBuffer == null)
{
if (!m_buffers.TryTake(out m_currentBuffer, -1))
{
return 0;
}
m_readFromCurrent = 0;
}
int toRead = Math.Min(count, m_currentBuffer.Length - m_readFromCurrent);
Array.Copy(m_currentBuffer, m_readFromCurrent, buffer, offset, toRead);
m_readFromCurrent += toRead;
if (m_readFromCurrent == m_currentBuffer.Length)
m_currentBuffer = null;
return toRead;
}
public override void Write(byte[] buffer, int offset, int count)
{
throw new NotSupportedException();
}
public override bool CanRead
{
get { return true; }
}
public override bool CanSeek
{
get { return false; }
}
public override bool CanWrite
{
get { return false; }
}
public override long Length
{
get { throw new NotSupportedException(); }
}
public override long Position
{
get { throw new NotSupportedException(); }
set { throw new NotSupportedException(); }
}
}
private class WriterStream : Stream
{
private readonly BlockingCollection<byte[]> m_buffers;
public WriterStream(BlockingCollection<byte[]> buffers)
{
m_buffers = buffers;
}
public override void Flush()
{}
public override long Seek(long offset, SeekOrigin origin)
{
throw new NotSupportedException();
}
public override void SetLength(long value)
{
throw new NotSupportedException();
}
public override int Read(byte[] buffer, int offset, int count)
{
throw new NotSupportedException();
}
public override void Write(byte[] buffer, int offset, int count)
{
if (count == 0)
return;
var copied = new byte[count];
Array.Copy(buffer, offset, copied, 0, count);
m_buffers.Add(copied);
}
public override bool CanRead
{
get { return false; }
}
public override bool CanSeek
{
get { return false; }
}
public override bool CanWrite
{
get { return true; }
}
public override long Length
{
get { throw new NotSupportedException(); }
}
public override long Position
{
get { throw new NotSupportedException(); }
set { throw new NotSupportedException(); }
}
protected override void Dispose(bool disposing)
{
m_buffers.CompleteAdding();
base.Dispose(disposing);
}
}
public Stream Reader
{
get { return m_reader; }
}
public Stream Writer
{
get { return m_writer; }
}
}
不幸的是,您无法从同一线程同时读取和写入这些流。但是你可以使用
Task
从另一个线程写入:XDocument doc = …;
var forwardingStream = new ForwardingStream();
var client = new HttpClient();
var content = new StreamContent(forwardingStream.Reader);
Task.Run(() => doc.Save(forwardingStream.Writer));
var response = client.Post(url, content);
关于.net - 使用 HttpClient,如何将 XDocument 直接保存到请求流?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/9242835/