.NET(C#) HttpClient单例(Singleton)和每次请求new HttpClient对比

1､每次请求创建HttpClient实例

  public HttpClient GetConnection(int timeout,string baseAddress)        {            HttpClient httpClient = new HttpClient();            httpClient.BaseAddress = new Uri(baseAddress);             httpClient.Timeout = System.TimeSpan.FromMilliseconds(timeout);            return httpClient;        }

2､每次请求使用HttpClient单例

 private static readonly Lazy lazy =        new Lazy(() => new HttpClient());        public static HttpClient Instance { get { return lazy.Value; } }        private HttpClient getConnection(int timeout,string baseAddress)        {            Instance.Timeout = System.TimeSpan.FromMilliseconds(timeout);            //client.MaxResponseContentBufferSize = 500000;            Instance.BaseAddress = new Uri(baseAddress);            return Instance; ;        }

3､对比区别

HttpClient应该只被实例化一次，并在应用程序的整个生命周期中被重用。如为每个请求实例化一个HttpClient类将耗尽沉重负载下可用的套接字数量。这将导致SocketException错误。下面是正确使用HttpClient的示例。

// HttpClient是为每个应用程序实例化一次，而不是每次请求创建一个实例static readonly HttpClient client = new HttpClient();static async Task Main(){  // 在try/catch块中调用异步网络方法来处理异常。  try  {     HttpResponseMessage response = await client.GetAsync("http://www.contoso.com/");     response.EnsureSuccessStatusCode();     string responseBody = await response.Content.ReadAsStringAsync();     // string responseBody = await client.GetStringAsync(uri);     Console.WriteLine(responseBody);  }    catch(HttpRequestException e)  {     Console.WriteLine("\nException Caught!");     Console.WriteLine("Message :{0} ",e.Message);  }}

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