c# HttpClient超时重试

当使用c# HttpClient 发送请求时，由于网络等原因可能会出现超时的情况。为了提高请求的成功率，我们可以使用超时重试的机制。

超时重试的实现方式可以使用循环结构，在请求发起后等待一定时间，若超时未收到响应，则再次发起请求。循环次数可以根据实际情况进行设置，一般建议不超过三次。

百度搜索的关于c#HttpClient 的比较少，简单整理了下，代码如下

　　　　　　　　　　　　//调用方式 3秒后超时 重试2次        .net framework 4.5               
 　　　　　　　　　  　HttpMessageHandler handler = new TimeoutHandler(2,3000);
                    using (var client = new HttpClient(handler))
                    {
                        using (var content = new StringContent(""), null, "application/json"))
                        {
                            var response = client.PostAsync("url", content).Result;
                            string result = response.Content.ReadAsStringAsync().Result;
                            JObject jobj = JObject.Parse(result);
                            if (jobj.Value<int>("code") == 1)
                            {
                            }
                        }
                    }

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

public class TimeoutHandler : DelegatingHandler {     private int _timeout;     private int _max_count;     ///     /// 超时重试     ///     ///重试次数     ///超时时间     public TimeoutHandler( int max_count = 3,  int timeout = 5000)     {         base .InnerHandler =  new HttpClientHandler();         _timeout = timeout;         _max_count = max_count;     }       protected async  override Task SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)     {         HttpResponseMessage response =  null ;         for ( int i = 1; i <= _max_count + 1; i++)         {             var cts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);             cts.CancelAfter(_timeout);             try             {                  response = await  base .SendAsync(request, cts.Token);                   if (response.IsSuccessStatusCode)                 {                     return response;                 }             }             catch (Exception ex)             {                 //请求超时                 if (ex  is TaskCanceledException)                 {                     MyLogService.Print( "接口请求超时：" + ex.ToString());                     if (i > _max_count)                     {                         return new HttpResponseMessage(HttpStatusCode.OK)                         {                             Content =  new StringContent( "{\"code\":-1,\"data\":\"\",\"msg\":\"接口请求超时\"}" , Encoding.UTF8,  "text/json" )                         };                     }                     MyLogService.Print($ "接口第{i}次重新请求" );                 }                 else                 {                     MyLogService.Error( "接口请求出错：" + ex.ToString());                     return new HttpResponseMessage(HttpStatusCode.OK)                     {                         Content =  new StringContent( "{\"code\":-1,\"data\":\"\",\"msg\":\"接口请求出错\"}" , Encoding.UTF8,  "text/json" )                     };                 }             }         }         return response;     } }