使用 Service 或 IntentService 的 Android Client/Server Socket 通信

Question

到目前为止，我能够在一个安卓设备(wifi 网络共享/热点)上启动一个服务器，让客户端(另一个安卓)连接并向服务器发送消息。然后服务器回复了那个。我意识到我需要一种方法来保持服​​务器监听客户端，即使聊天应用程序没有运行。客户端应该能够发送消息并且服务器应该接收到它。 我应该使用 Service 还是 IntentService 来实现它？我不能从 AsyncTask 和 Service 扩展...如何实现它？一些示例代码会很棒。

这是我的服务器的样子:

public class Server extends AsyncTask<Integer, Void, Socket> {

    private ServerSocket serverSocket;
    private TextView textView;
    private String incomingMsg;
    private String outgoingMsg;

    public Server(TextView textView) {
        this.textView = textView;
    }

    public void closeServer() {
        try {
            serverSocket.close();
        } catch (IOException e) {
            Log.d("Server", "Closung the server caused a problem");
            e.printStackTrace();
        }       
    }


    @Override
    protected Socket doInBackground(Integer... params) {

        try {
            serverSocket = new ServerSocket(params[0]);       

            //accept connections
            Socket socket = serverSocket.accept();

            BufferedWriter out = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

            incomingMsg = in.readLine() + System.getProperty("line.separator");

            //send a message
            outgoingMsg = "You are connected to the Server" + System.getProperty("line.separator");
            out.write(outgoingMsg);
            out.flush();

            return socket;


        } catch (InterruptedIOException e) {
            //if timeout occurs
            e.printStackTrace();

        } catch (IOException e) {
            e.printStackTrace();

        } 
//      finally {
//          if (serverSocket != null) {
//              try {
//                  serverSocket.close();
//              } catch (IOException e) {
//                  e.printStackTrace();
//              }
//          }
//      }

        return null;
    }


    protected void onPostExecute(Socket socket) {

        if(socket != null) {
            try {

                Log.i("Server", "Server received: " + incomingMsg);
                textView.setText("Server received: " + incomingMsg + "\n");

                textView.append("Server sent: " + outgoingMsg + "\n");
                Log.i("Server", "Server sent: " + outgoingMsg);

                socket.close();

            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        } else {
            Log.d("Server", "Can't communicate with the client!");
        }
    }
}

这是我的客户:

public class Client extends AsyncTask<Integer, Void, Socket> {

    private WifiManager wifi;
    private Context context;
    private String outMsg;
    private String inMsg;

    public Client(Context context, WifiManager wifiManager) {
        this.context = context;
        this.wifi = wifiManager;
    }

    @Override
    protected Socket doInBackground(Integer... params) {

        try {

            String gateway = intToIp(wifi.getDhcpInfo().gateway);
            Socket socket = new Socket(gateway, params[0]);

            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            BufferedWriter out = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));

            String ipAdress = intToIp(wifi.getConnectionInfo().getIpAddress());

            outMsg = ", Client " + ipAdress +" is connecting!" + System.getProperty("line.separator"); 
            out.write(outMsg);
            out.flush();

            //accept server response
            inMsg = in.readLine() + System.getProperty("line.separator");

            return socket;

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null; 
    }


    public String intToIp(int addr) {
        return  ((addr & 0xFF) + "." + 
                ((addr >>>= 8) & 0xFF) + "." + 
                ((addr >>>= 8) & 0xFF) + "." + 
                ((addr >>>= 8) & 0xFF));
    }


    protected void onPostExecute(Socket socket) {

        if(socket != null) {

            Log.i("Client", "Client sent: " + outMsg);
            Toast.makeText(context, "\nClient sent: " + outMsg + "\n", Toast.LENGTH_LONG).show();

            Log.i("Client", "Client received: " + inMsg);
            Toast.makeText(context, "Client received: " + inMsg + "\n", Toast.LENGTH_LONG).show();

        } else {
            Log.d("Client", "Can't connect to server!");
            Toast.makeText(context, "Can't connect to server!", Toast.LENGTH_LONG).show();
        }           
    }
}

如何从服务器创建服务？客户端也应该是服务吗？

Answer 1

使用服务但忘记 AsyncTask。让你的服务启动你的通用线程(https://developer.android.com/reference/java/lang/Thread.html)并设置你的套接字+监听器。该服务甚至还可以处理消息的发送(通过以下链接中涵盖的众多选项之一)。

不要忘记在服务的 onDestroy() 中正确清理线程。

另请注意，如果您希望该应用继续接收来自其他客户端的消息，您需要确保该服务被强制进入前台(参见 http://developer.android.com/reference/android/app/Service.html#startForeground(int ，android.app.Notification)。然而，这并非万无一失，您的服务仍可能被终止。

这就是为什么人们倾向于使用托管在某个专用盒子上的服务器，而不是每个单独的设备...