.Net高效UDP異步編程

     因爲要寫一個網絡程序要用到UDP協議,UDP這東西比較麻煩,又不像TCP一樣提供可靠的連接,發送接收的超時實在不好設計,最後只要用Timer來檢測有沒有想要的數據包-_#,不過這不是這次的重點,重點是怎麼建立一種高效的UDP機制來實時接收服務器發送過來的數據包.

     CodeProject上有個例子是開個線程去同步接收,這樣倒是可以滿足我的程序需求,不過實際中遇到幾個問題:

     1.程序開銷大,內存狂飆,接一次數據就要重新開一次線程

     2.由於主界面和底層是完全隔離只是通過中間的接口來通訊,導致線程總是不能正常的結束,程序結束後還有一個進程在那裏不知道幹什麼.

     於是翻閱MSDN,查找自己以前寫的代碼,最後還是決定用異步來接收,MSDN上UDP異步的例子不太好,有點敷衍的意思,用異步很好的解決了以上的問題,高效完成效率,代碼如下: 

 

UdpClient qq_client;    //Udp客戶端
qq_client = new UdpClient();
IPEndPoint remoteQQEP = new IPEndPoint(remotehost, remoteport);
qq_client.Connect(remoteQQEP);


AsyncCallback GetRecvBuffer = new AsyncCallback(ReceiveCallback);
qq_client.BeginReceive(GetRecvBuffer, null);   

這裏用一個GetRecvBuffer的回掉來實現異步

 

        private void ReceiveCallback(IAsyncResult ar)
        ...{
            try
            ...{
                lock (this)
                ...{
                    byte[] recvbytes = qq_client.EndReceive(ar, ref remoteQQEP);
                    //QQFunction.DebugDump(recvbytes);


                    if (recvbytes[0] != QQDef.QQ_IM_HEAD && recvbytes[0] != 0x03)
                    ...{
                        //非QQ數據包
                        return;
                    }
                    switch (Pop16(recvbytes, 3))
                    ...{
                        case QQDef.QQ_REQUEST_TOKEN:
                            DoGetToken(recvbytes);
                            break;
                        case QQDef.QQ_REQUEST_LOGIN:
                            DoGetLogin(recvbytes);
                            break;
                        case QQDef.QQ_GET_ONLINE_FRIEND:
                            DoGetOnline(recvbytes);
                            break;
                        case QQDef.QQ_KEEP_ALIVE:
                            CheckAlive(recvbytes);
                            break;
                        case QQDef.QQ_SEND_IM_MSG:
                            // Do SomeThing
                            break;
                        case QQDef.QQ_RECV_IM_MSG:
                            DoRecvMsg(recvbytes);
                            break;
                        default:
                            QQFunction.DebugDump("UnKnow Command");
                            QQFunction.DebugDump(recvbytes);
                            break;
                    }
                    
                }
                lock (this)
                ...{
                    AsyncCallback GetRecvBuffer = new AsyncCallback(ReceiveCallback);
                    qq_client.BeginReceive(GetRecvBuffer, null);
                }
            }
            catch
            ...{
            }
        }

 

代碼是不是很簡單?功能是不是很強大?