在Windows Phone 8.1中快速发送HTTP命令

Question

I have a Vu+ satellite box and I am developing a WP8.1 remotecontrol for the box.

The Vu+ box has a webservice and takes command like: http://192.168.1.11/web/remotecontrol?command= {0}

My code is like this:

  private void Button_Click(object sender, RoutedEventArgs e)
    {
        try
        {
            string cmd = ((Button)sender).Tag.ToString();
            SendBtnCommand(cmd);
        }
        catch { }

    }

    private async void SendBtnCommand(string cmd)
    {
        using (HttpClient h = new HttpClient())
        {
            string x = await h.GetStringAsync(string.Format("http://192.168.1.11/web/remotecontrol?command={0}", cmd));
        }

    }

But it seems that the connection does not close. I can only send the same command one time and then have to wait a minute before sending the same command again. I can send multiple different commands in a row.

Any help on how to optimize this?

Answer 1

Instead of passing additional parameter in your url, you can turn off caching.

using (var h = new HttpClient())
        {
            h.DefaultRequestHeaders.CacheControl = new CacheControlHeaderValue {NoCache = true};
            string x = await h.GetStringAsync(string.Format("http://192.168.1.11/web/remotecontrol?command={0}", cmd));
        }

There's another solution for this caching problem. You can override default httpClientHandler like this

public class BypassCacheHttpRequestHandler : HttpClientHandler
{
    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        if (request.Headers.IfModifiedSince == null)
            request.Headers.IfModifiedSince = new DateTimeOffset(DateTime.Now);
        return base.SendAsync(request, cancellationToken);
    }
}

While initiating your httpClient, you can pass above handler to avoid caching issue

using (var h = new HttpClient((new BypassCacheHttpRequestHandler(), true))
{
 string x =await h.GetStringAsync(string.Format("http://192.168.1.11/web/remotecontrol?command={0}", cmd));
}

Source: https://stackoverflow.com/a/25613559/546896

Answer 2

Came up with ugly hack. I will try to see how I can implement headers, though.

string x = await h.GetStringAsync(string.Format("http://192.168.1.11/web/remotecontrol?command={0}&{1}", cmd, DateTime.Now.Millisecond));

That way the same command don't get cached.