AutoServer AutoClient

socket.java

import java.io.*;
import java.net.*;

abstract class Client
{
  Socket socket;
  ObjectOutputStream out;
  boolean closed;

  void init(final Socket newSocket) {
    new Thread() {
      public void run() {
        try {
          socket = newSocket;
          out = new ObjectOutputStream(socket.getOutputStream());
          onOpen();
          ObjectInputStream in = new ObjectInputStream(socket.getInputStream());
          while (true) {
            onMessage(in.readObject());
          }
        } catch (Exception e) {
          close();
        }
      }
    }.start();
  }

  Client(Socket socket) {
    init(socket);
  }

  Client(String host, int port) {
    try {
      init(new Socket(host, port));
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }

  abstract void onOpen();

  abstract void onClose();

  abstract void onMessage(Object data);

  void send(final Object data) {
    new Thread() {
      public void run() {
        try {
          out.writeObject(data);
        } catch (Exception e) {
          close();
        }
      }
    }.start();
  }

  void close() {
    try {
      if (!closed) {
        closed = true;
        onClose();
        socket.close();
      }
    } catch (Exception e) {
    }
  }
}

abstract class Server
{
  Server(final int port) {
    new Thread() {
      public void run() {
        try {
          ServerSocket socket = new ServerSocket(port);
          while (true) {
            new Client(socket.accept()) {
              void onOpen() {
                Server.this.onOpen(this);
              }
              void onClose() {
                Server.this.onClose(this);
              }
              void onMessage(Object data) {
                Server.this.onMessage(this, data);
              }
            };
          }
        } catch (Exception e) {
          throw new RuntimeException(e);
        }
      }
    }.start();
  }

  abstract void onOpen(Client client);

  abstract void onClose(Client client);

  abstract void onMessage(Client client, Object data);
}

abstract class AutoServer
{
  AutoServer() {
    new Server(1111) {
      void onOpen(Client client) {
        AutoServer.this.onOpen(client);
      }
      void onClose(Client client) {
        AutoServer.this.onClose(client);
      }
      void onMessage(Client client, Object data) {
        AutoServer.this.onMessage(client, data);
      }
    };
    new Thread() {
      public void run() {
        try {
          DatagramSocket socket = new DatagramSocket();
          DatagramPacket packet = new DatagramPacket(
            new byte[] {1, 1, 1, 1},
            4,
            InetAddress.getByName("255.255.255.255"),
            1110);
          while (true) {
            socket.send(packet);
            Thread.sleep(1000);
          }
        } catch (Exception e) {
        }
      }
    }.start();
  }

  abstract void onOpen(Client client);

  abstract void onClose(Client client);

  abstract void onMessage(Client client, Object data);
}

abstract class AutoClient
{
  Client client;

  void init() {
    new Thread() {
      public void run() {
        try {
          try (DatagramSocket socket = new DatagramSocket(1110)) {
            DatagramPacket packet = new DatagramPacket(new byte[4], 4);
            while (true) {
              socket.receive(packet);
              if (packet.getData()[0] == 1 && packet.getData()[1] == 1 && packet.getData()[2] == 1 && packet.getData()[3] == 1) {
                client = new Client(packet.getAddress().getHostAddress(), 1111) {
                  void onOpen() {
                    AutoClient.this.onOpen();
                  }
                  void onClose() {
                    AutoClient.this.onClose();
                    client = null;
                    AutoClient.this.init();
                  }
                  void onMessage(Object data) {
                    AutoClient.this.onMessage(data);
                  }
                };
                break;
              }
            }
          }
        } catch (Exception e) {
        }
      }
    }.start();
  }

  AutoClient() {
    init();
  }

  abstract void onOpen();

  abstract void onClose();

  abstract void onMessage(Object data);

  void send(Object data) {
    if (client != null) {
      client.send(data);
    }
  }

  void close() {
    if (client != null) {
      client.close();
    }
  }
}

test.java

class AutoServerTest {
  public static void main(String[] args) {
    new AutoServer() {
      void onOpen(Client client) {
        System.out.println("[AUTOSERVER] onOpen");
        client.send("Hello from server!");
      }
      void onClose(Client client) {
        System.out.println("[AUTOSERVER] onClose");
      }
      void onMessage(Client client, Object data) {
        System.out.println("[AUTOSERVER] onMessage " + data);
      }
    };
  }
}

class AutoClientTest {
  public static void main(String[] args) {
    new AutoClient() {
      void onOpen() {
        System.out.println("[AUTOCLIENT] onOpen");
        send("Hello from client!");
      }
      void onClose() {
        System.out.println("[AUTOCLIENT] onClose");
      }
      void onMessage(Object data) {
        System.out.println("[AUTOCLIENT] onMessage " + data);
      }
    };
  }
}