HttpClient GetStreamAsync 和 HTTP 状态代码？

Question

我希望使用 json.net performance tips documentation, however I'm unable to find how to get a hold of the http status codes without the typical awaiting the HttpResponse 推荐的流。

有没有办法先获取状态码而不读取数据？所以还在利用流？

Answer 1

我还没有测试以确保它的性能，但这看起来很有希望：

using(HttpClient client = new HttpClient())
{
    var response = await client.GetAsync("http://httpbin.org/get", HttpCompletionOption.ResponseHeadersRead);

    response.EnsureSuccessStatusCode();

    using (var stream = await response.Content.ReadAsStreamAsync())
    using (var streamReader = new StreamReader(stream))
    using (var jsonReader = new JsonTextReader(streamReader))
    {
      var serializer = new JsonSerializer();

       //do some deserializing http://www.newtonsoft.com/json/help/html/Performance.htm
    }
}

Answer 2

我更喜欢通过 using 处理 HttpResponseMessage，因为它是一次性的。我也不想依赖异常处理来处理失败的请求。相反，我更喜欢检查 IsSuccessStatusCode 布尔值并相应地进行。例如：

using(HttpClient client = new HttpClient())
{
    using(var response = await client.GetAsync("http://httpbin.org/get", HttpCompletionOption.ResponseHeadersRead))
    {
        if(response.IsSuccessStatusCode)
        {
            using (var stream = await response.Content.ReadAsStreamAsync())
            using (var streamReader = new StreamReader(stream))
            using (var jsonReader = new JsonTextReader(streamReader))
            {
              var serializer = new JsonSerializer();

               //do some deserializing http://www.newtonsoft.com/json/help/html/Performance.htm
            }
        }
        else {
            //do your error logging and/or retry logic
        }
    }       
}

EDIT: If you're doing work with a rate limited api sending the HEAD request just isn't sometimes feasible. As such, here's a code sample using the good ol' fashion HttpWebRequest (note that there isn't a better way to deal with http errors than WebException in this case):

var req = WebRequest.CreateHttp("http://httpbin.org/get");

/*
 * execute
 */
try
{
    using (var resp = await req.GetResponseAsync())
    {
        using (var s = resp.GetResponseStream())
        using (var sr = new StreamReader(s))
        using (var j = new JsonTextReader(sr))
        {
            var serializer = new JsonSerializer();
            //do some deserializing http://www.newtonsoft.com/json/help/html/Performance.htm
        }
    }
}
catch (WebException ex)
{
    using (HttpWebResponse response = (HttpWebResponse)ex.Response)
    {
        using (StreamReader sr = new StreamReader(response.GetResponseStream()))
        {
            string respStr = sr.ReadToEnd();
            int statusCode = (int)response.StatusCode;

            //do your status code logic here
        }
    }
}

HttpClient GetStreamAsync 和 HTTP 状态代码？

HttpClient GetStreamAsync and HTTP status codes?

c#

stream

httpclient

json.net