Android，Java，套接字，确定远程主机断开连接

Question

I'm trying to code a TCP client in android java. Most works fine. But i have one issue. If the socket is connected and the remeote host shuts down or the network goes down or something else, the socket.getinputstream keeps blocking.

I don't know if the socket is still connected. I code in objective-c too and in objective-c i get an event that the socket forcefully shuts down and i can try to reconnect. So on objective c the socket tracks the state.

In java the socket and the inputstream is still connected or blocked even the socket is down. How can i check if the socket is still connected?

        @Override
        protected Void doInBackground(String... params) {
        try {
                    String host = params[0];
                    int port = Integer.parseInt(params[1]);
                    SocketAddress sockaddr = new InetSocketAddress(host, port);
                    Socket socket = new Socket();
                    socket.connect(sockaddr,5000);
                    socket.setSoTimeout(7000);

                    out = new PrintWriter(socket.getOutputStream(), true);
                    mBufferIn = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                    while (mRun) {
                        try {
             ----->         mServerMessage = mBufferIn.readLine();
                        }catch (Exception e){
                            Log.d("my","hier3" + e.getMessage());
                        }
                        if (mServerMessage.trim() != null) {

                                sender.messageReceived(s2);

                             }else{

                            }

                        }

                    }

                } catch (UnknownHostException e

) {

Answer 1

The question of how to detect if the remote peer/socket has closed the connection has been answered here as well as here . Basically, the answers suggest that you attempt to read from the socket, and then observe what happens ( read() returns -1 , or readLine() returns null or your read methods raise EOFException .