我们知道 Socket Blocking 属性默认true . 表明Socket 处于同步调用 , Connect , 或 Send , Receive 需等待动作 完成才能继续执行。
有一种应用场景 , Socket 处于 同步调用状态。 我们希望 Receive 时,若没数据,立即返回,而不是阻塞状态。 这里用到两个属性:
Available : 返回可读取字节数
Poll : 检测Socket 状态(是否可读,可写,及异常情况)。无法检测物理层断开产生异常
示例代码:
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 61 62 63 64 65 66 67 68 69 | #region socket 测试 Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); s.Blocking = true ; // Connects to host using IPEndPoint. s.Connect( "42.121.252.58" , 80); // s.Connect("192.168.113.128", 11000); if (!s.Connected) { Console.WriteLine( "Unable to connect to host" ); } byte [] byt = new byte [4096]; int length; if (!s.Poll(100, SelectMode.SelectRead)) { Console.WriteLine( "socket not read..." ); } if (!s.Poll(50, SelectMode.SelectWrite)) { Console.WriteLine( "socket not write..." ); } string strRequest = @"GET http://www.cnblogs.com/ HTTP/1.1 Host: www.cnblogs.com User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:47.0) Gecko/20100101 Firefox/47.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3 Accept-Encoding: deflate Cookie: __utma=226521935.655192264.1463987470.1467102370.1467253211.26; __utmz=226521935.1467253212.26.16.utmcsr=baidu|utmccn=(organic)|utmcmd=organic; _ga=GA1.2.655192264.1463987470; CNZZDATA2017822=cnzz_eid%3D985476095-1464072054-null%26ntime%3D1464072054; pgv_pvi=6786726912; AJSTAT_ok_times=10; CNZZDATA1000085291=2001773208-1464232710-null%7C1464232710; Hm_lvt_5d6cc4516947da0ee2209a48877c77e9=1464232694,1464232700,1464233056,1464234704; Hm_lvt_3c14eade5a5788be714db0f403aeaf46=1464592341,1464597543; CNZZDATA2081367=cnzz_eid%3D999995175-1464743380-null%26ntime%3D1464743380; CNZZDATA1943205=cnzz_eid%3D1332194-1464919429-null%26ntime%3D1464919429; CNZZDATA706677=cnzz_eid%3D1663091018-1465265577-null%26ntime%3D1465265950; CNZZDATA5343953=cnzz_eid%3D1996425634-1465290765-null%26ntime%3D1465290765; a8178_times=1; CNZZDATA1028890=cnzz_eid%3D713750658-1465715751-null%26ntime%3D1465715751; CNZZDATA2686777=cnzz_eid%3D1376577942-1465895035-http%253A%252F%252Fwww.cnblogs.com%252F%26ntime%3D1465895035; SyntaxHighlighter=csharp; CNZZDATA1258105384=1452308944-1466386727-http%253A%252F%252Fwww.cnblogs.com%252F%7C1466397796; CNZZDATA1259569345=1538663036-1466750971-http%253A%252F%252Fwww.cnblogs.com%252F%7C1466750971; __utmc=226521935; .CNBlogsCookie=6A451D1565F1FA00C8931473EEFE1D227C0F57F40018603D027DDA2C24697584375F41D8BA527CDF6EB23CD3ABFA9D5BCAB249EE942E36822F74DCFC65AC447C4FCCA67EF6A15F0ABA6BF930FB3434BFC90254CA Connection: keep-alive If-Modified-Since: Thu, 30 Jun 2016 03:33:14 GMT " ; int i = s.Send(Encoding.UTF8.GetBytes(strRequest)); Console.WriteLine( "成功发送数据:{0}" , i); //发送数据后等待 50 ms System.Threading.Thread.Sleep(50); if (!s.Poll(200, SelectMode.SelectRead)) { Console.WriteLine( "re: socket not read..." ); } else { // byt = new byte[1]; do { length = s.Receive(byt); Console.WriteLine(System.Text.Encoding.UTF8.GetString(byt, 0, length)); //} while (s.Poll(500, SelectMode.SelectRead) && s.Available > 0 && s.Connected); } while (s.Available > 0); //Poll 可检测缓冲区是否还有数据可读。 , 如 socket 处于 blocking 状态 , Receive 时 防止 blocking , 可先调用 Poll 检测是否可读, 同时 Available 属性 应大于 0 , 再调用 Receive // } while (s.Poll(500, SelectMode.SelectRead)); } if (!s.Poll(50, SelectMode.SelectWrite)) { Console.WriteLine( "re: socket not write..." ); } s.Shutdown(SocketShutdown.Both); s.Close(); #endregion |
· 一个费力不讨好的项目,让我损失了近一半的绩效!
· .NET Core 托管堆内存泄露/CPU异常的常见思路
· PostgreSQL 和 SQL Server 在统计信息维护中的关键差异
· C++代码改造为UTF-8编码问题的总结
· DeepSeek 解答了困扰我五年的技术问题
· 一个费力不讨好的项目,让我损失了近一半的绩效!
· 清华大学推出第四讲使用 DeepSeek + DeepResearch 让科研像聊天一样简单!
· 实操Deepseek接入个人知识库
· CSnakes vs Python.NET:高效嵌入与灵活互通的跨语言方案对比
· Plotly.NET 一个为 .NET 打造的强大开源交互式图表库