客户端重新连接Java套接字

Question

好的，我需要编写一个能够检测到客户端和服务器之间连接的客户端...一旦服务器关闭并重新启动，我的客户端就需要能够将其重新连接到服务器..但是我真的不是确定如何做...如果有帮助的话吗？

 public TEST(String serverIP, int serverPort){
    Log("Connection to the Server....");
    try{
        socket = new Socket(serverIP, serverPort);
        Log("Connected to the server : "+socket);
        start();
    } catch(UnknownHostException uhe){
        System.out.println("Unknown Host: "+ uhe.getMessage());
    } catch (IOException ioe){
        System.out.println("IO Exception: "+ioe.getMessage());
    }

    String readline = "";

    streamOutput.println("TRY test");

    while(true){
        try{
            readline = streamInput.readLine();
            System.out.println(readline);
        } catch (IOException ioe){
            System.out.println("Error in sending: "+ioe.getMessage());
            return;
        }
    }
}

上面是我的客户端代码，用于在服务器编译后用于连接服务器...

Answer 1

知道连接已关闭的唯一方法是尝试通过线路发送数据。连接不会自动测试打开/关闭状态。如果要检查是否已关闭连接并重新连接，则必须将心跳信号从一个发送到另一个。通常，它只是一个特殊的字节或微小的消息，告诉对方“我还在这里”

但是，然后，根据您的应用程序，您可能不需要。您的应用程序的两面都启动消息吗？还是RMI风格的应用程序？服务器仅在哪里侦听请求？

也许是这样的吗？

    class Client {
        private Socket socket;
        private boolean tryToReconnect = true;
        private final Thread heartbeatThread;
        private long heartbeatDelayMillis = 5000;

        public Client(final String server, final int port) {
            connect(server, port);
            heartbeatThread = new Thread() {
                public void run() {
                    while (tryToReconnect) {
                        //send a test signal
                        try {
                            socket.getOutputStream().write(666);
                            sleep(heartbeatDelayMillis);
                        } catch (InterruptedException e) {
                            // You may or may not want to stop the thread here
                            // tryToReconnect = false;
                        } catch (IOException e) {
                            logger.warn("Server is offline");
                            connect(server, port);
                        }
                    }
                };
            };
            heartbeatThread.start();
        }

        private void connect(String server, int port){
            try {
                socket = new Socket(server, port);
            } catch (UnknownHostException e) {
                logger.error(e, e);
            } catch (IOException e) {
                logger.error(e, e);
            }
        }

        public void shutdown() {
            tryToReconnect = false;
        }
    }