考虑以下代码片段:
public static Task<string> FetchAsync()
{
string url = "http://www.example.com", message = "Hello World!";
var request = (HttpWebRequest)WebRequest.Create(url);
request.Method = WebRequestMethods.Http.Post;
return Task.Factory.FromAsync<Stream>(request.BeginGetRequestStream, request.EndGetRequestStream, null)
.ContinueWith(t =>
{
var stream = t.Result;
var data = Encoding.ASCII.GetBytes(message);
Task.Factory.FromAsync(stream.BeginWrite, stream.EndWrite, data, 0, data.Length, null, TaskCreationOptions.AttachedToParent)
.ContinueWith(t2 => { stream.Close(); });
})
.ContinueWith<string>(t =>
{
var t1 =
Task.Factory.FromAsync<WebResponse>(request.BeginGetResponse, request.EndGetResponse, null)
.ContinueWith<string>(t2 =>
{
var response = (HttpWebResponse)t2.Result;
var stream = response.GetResponseStream();
var buffer = new byte[response.ContentLength > 0 ? response.ContentLength : 0x100000];
var t3 = Task<int>.Factory.FromAsync(stream.BeginRead, stream.EndRead, buffer, 0, buffer.Length, null, TaskCreationOptions.AttachedToParent)
.ContinueWith<string>(t4 =>
{
stream.Close();
response.Close();
if (t4.Result < buffer.Length)
{
Array.Resize(ref buffer, t4.Result);
}
return Encoding.ASCII.GetString(buffer);
});
t3.Wait();
return t3.Result;
});
t1.Wait();
return t1.Result;
});
}
它应该返回Task<string>
,发送带有一些数据的HTTP POST请求,以字符串形式从web服务器返回结果,并尽可能高效。
- 您在上面的示例中发现了任何异步流问题吗?
- 在此示例中,在
.ContinueWith()
内使用.Wait()
是否可以? - 除了异常处理之外,您是否看到此代码的其他问题?