我正在开发一个需要与 TCP 套接字通信的应用程序。我设置了一个作为我的 TCP 服务器的服务和一个作为我的 TCP 客户端的 Activity 。

我在发送消息和从服务器接收答复之间有很大的延迟，例如 10 秒或更长时间。经过几天的研究，我发现了如何根据客户端请求设置超时，并且一切正常。

所以我的问题是，是否必须为 TCP 连接设置超时，否则它不起作用或者我的实现有其他问题？

这是我的客户端代码:

public static void sendTCP(final InetAddress senderAddr, final String Msg, final int serverPort) {
        Thread tclient = new Thread(){
            public void run() {
                boolean connected;
                Socket socket = new Socket();
                try {
                    Log.d("TCP", "Client: Connecting...");
                    socket.bind(null);
                    socket.connect((new InetSocketAddress(senderAddr, serverPort)), 1000);
                    connected = true;
                try {
                    Log.d("TCP", "Client: Sending command.");
                    PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);
                    out.println(Msg);
                    out.close();
                } 
                catch (Exception e) {
                    Log.e("TCP", "Client: Error sending.", e);
                }
                } catch (Exception e) {
                    Log.e("TCP", "Client: Error connecting.", e);
                    connected = false;
                }
                finally {
                    if (socket != null) {
                        if (socket.isConnected()) {
                            try {
                                socket.close();
                                Log.d("TCP", "Client: Connection Closed.");
                            } catch (IOException e) {
                                Log.e("TCP", "Client: Error closing connection.", e);
                            }
                        }
                    }
                }
            }
        };
        tclient.start();
    }

和服务器的:

public void onStart(Intent intent, int startid) {

    t = new Thread(){
         public void run() {
             try {
                Boolean end = false;
                Log.d("TCP", "Server: Creating server.");
                ServerSocket ss = new ServerSocket(TCPPORT);
                while(!end) {
                    //Server is waiting for client here, if needed
                    Log.d("TCP", "Server: Waiting on packet!");
                    Socket s = ss.accept();
                    BufferedReader input = new BufferedReader(new InputStreamReader(s.getInputStream()));
                    String st = input.readLine();
                    Log.d("TCP", "Server: Message received from client: "+st);

                    InetAddress senderAddr = s.getInetAddress();
                    senderAddrString= senderAddr.getHostAddress();

                    myAddrString = GetLocalIpAddress();
                    myAddr = InetAddress.getByName(myAddrString);

                    if (senderAddr.equals(myAddr)) {
                    }
                    else {
                        //Estraggo dal pacchetto ricevuto
                        try {
                            StringTokenizer tokens = new StringTokenizer(st, "|");
                            flag = tokens.nextToken();
                            userid = tokens.nextToken();
                            payload = tokens.nextToken();
                        }
                        catch (Exception e) {
                            Log.e("TCP", "Server: Errore estrazione dati.");
                        }

                        if (flag.equals(Constants.flag_scan_answer)) {
                            Log.d("TCP", "Server: Flag answer");
                            //devo passare i dati ad un database ScanActivity

                            //database(senderAddrString,userid);

                            System.out.println("RISPOSTA RICEVUTA DAL SERVICE TCP");
                            System.out.println("FLAG " + flag);
                            System.out.println("USERID " + userid);
                            System.out.println("PAYLOAD " + payload);

                            announceReceivingPacket();
                        }

                        else {
                            Log.d("TCP", "Server: CASO NON PREVISTO");
                        }
                    }
                    s.close();
                }
            }
            catch (UnknownHostException e) {
                    e.printStackTrace();
            } 
            catch (IOException e) {
                    e.printStackTrace();
            }
         }
    };
    t.start();
 }

最佳答案

it's mandatory to set up timeout for a TCP connection

这不是强制性的，但这是一个非常好的主意。首先将其设置为预期服务时间的两倍或三倍，然后进行调整，以免出现误报。默认的读取超时是无限的，而且我已经看到整个平台以读取超时之外的任何其他方式无法被读取器检测到的方式发生故障。

参见 here获取相关报价。

关于java - Android TCP套接字超时，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13759170/