c# - HttpResponseMessage.Content.ReadAsStreamAsync() 与 HttpResponseMessage.Content.ReadAsStringAsync()

Question

var request = new HttpRequestMessage(HttpMethod.Get, $"api/Items");
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

using (var response = await _httpClient.SendAsync(request))
{
   response.EnsureSuccessStatusCode();
   var stream = await response.Content.ReadAsStreamAsync();        

     using (var streamReader = new StreamReader(stream))
     {
       using (var jsonTextReader = new JsonTextReader(streamReader))
       {
         var jsonSerializer = new JsonSerializer();
         var data =  jsonSerializer.Deserialize<Item>(jsonTextReader);
       }
     }
}

...

var request = new HttpRequestMessage(HttpMethod.Get, "api/Items");
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
var response = await _httpClient.SendAsync(request);

response.EnsureSuccessStatusCode();

var content = await response.Content.ReadAsStringAsync();
var data = JsonConvert.DeserializeObject<List<Item>>(content);

我已经运行了这两个示例，我很好奇它们总是得到相同结果的区别是什么，ReadAsStreamAsync 比 ReadAsStringAsync 快得多。

Answer 1

在引擎盖下，HttpClient将内容存储在 MemoryStream .所以，基本上叫 ReadAsStreamAsync只返回对流的引用。拨打ReadAsStringAsync的情况下, ToArray方法在内存流上被调用，因此创建了一个额外的数据副本。