import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketAddress;


public class ServerDemo {


    /** If using the IPv4 address structure to build the service, use IPV4_HOST */
    public static final String IPV4_HOST = "0.0.0.0";


    /** If using the IPv6 address structure to build the service, use IPV6_HOST */
    public static final String IPV6_HOST = "::";


    public static void main(String[] args) {
        int serverPort = 10000;
        try (ServerSocket serverSocket = new ServerSocket()) {
            // Setting address reuse
            serverSocket.setReuseAddress(true);
            // Bound server address and port, using IPv4 here
            serverSocket.bind(new InetSocketAddress(InetAddress.getByName(IPV4_HOST), serverPort));
            System.out.println("Server is listening on port " + serverPort);


            while (true) {
                // Accepting Client connections
                Socket clientSocket = serverSocket.accept();
                System.out.println("New client connected: " + clientSocket.getRemoteSocketAddress());


                // Processing Client requests
                handleClientRequest(clientSocket);
            }
        } catch (IOException e) {
            System.err.println("Failed to create server socket: " + e.getMessage());
        }
    }


    /**
     * Processing Function, site business implement, here is just an example
     * The purpose of this Function is to Return the Client's input verbatim to the Client
     */
    private static void handleClientRequest(Socket clientSocket) {
        try (InputStream inputStream = clientSocket.getInputStream();
             OutputStream outputStream = clientSocket.getOutputStream()) {


            // Reading the Data received from the Client
            byte[] buffer = new byte[1024];
            int bytesRead;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                // Reply the received Data to the Client as it is
                outputStream.write(buffer, 0, bytesRead);
            }


        } catch (IOException e) {
            // When the Client disconnects
            System.err.println("Failed to handle client request: " + e.getMessage());
        } finally {
            try {
                clientSocket.close();
            } catch (IOException e) {
                System.err.println("Failed to close client socket: " + e.getMessage());
            }
        }
    }
}