Socket (Java Platform SE 6)
Krótko o działaniu aplikacji. Po uruchomieniu serwer oczekuje na połączenie. Po połączeniu serwer wysyła do klienta komunikat "Ping" i oczekuje na odpowiedź. Jeśli klient odpowie "Pong" to serwer po 5 sekundach ponownie wysyła "Ping". W przypadku otrzymania złej odpowiedzi serwer się wyłącza.
Klient sprawdza nadchodzące komunikaty, jeśli otrzyma "Ping" to odpowiada "Pong". Dla celów testowych klient po 30 sekundach działania wyśle komunikat "Pon g" zamiast "Pong" i się wyłączy.
Linijki potrzebne do działania po stronie serwera:
/*Utworzenie na podanym porcie socketa serwera.*/ ServerSocket serverSocket = new ServerSocket(PORT); /*Oczekiwanie na połączenie i zaakceptowanie*/ Socket clientSocket = serverSocket.accept(); /*Utworzenie strumieni wejściowego i wyjściowego*/ PrintWriter out = new PrintWriter(clientSocket.getOutputStream(),true); BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); /*Wysłanie komunikatu*/ out.println(KOMUNIKAT); /*Oczekiwanie i odebranie komunikatu*/ String input = in.readLine(); /*Zamknięcie strumieniu i socketów*/ out.close(); in.close(); clientSocket.close(); serverSocket.close();
Linijki potrzebne do działania po stronie klienta:
/*Połączenie z serwerem*/ Socket socket = new Socket(HOST, PORT); /*Reszta analogicznie jak w serwerze*/
Kod źródłowy:
/* Server.java */
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
public class Server
{
private static final int PORT = 50000;
static boolean flaga = true;
private static ServerSocket serverSocket;
private static Socket clientSocket;
public static void main(String[] args) throws IOException
{
serverSocket = null;
try
{
serverSocket = new ServerSocket(PORT);
}
catch(IOException e)
{
System.err.println("Could not listen on port: "+PORT);
System.exit(1);
}
System.out.print("Wating for connection...");
Thread t = new Thread(new Runnable()
{
public void run()
{
try
{
while(flaga)
{
System.out.print(".");
Thread.sleep(1000);
}
}
catch(InterruptedException ie)
{
//
}
System.out.println("\nClient connected on port "+PORT);
}
});
t.start();
clientSocket = null;
try
{
clientSocket = serverSocket.accept();
flaga = false;
}
catch(IOException e)
{
System.err.println("Accept failed.");
t.interrupt();
System.exit(1);
}
final PrintWriter out = new PrintWriter(clientSocket.getOutputStream(),true);
final BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
t = new Thread(new Runnable()
{
public void run()
{
try
{
Thread.sleep(5000);
while(true)
{
out.println("Ping");
System.out.println(System.currentTimeMillis()+" Ping sent");
String input = in.readLine();
if(input.equals("Pong"))
{
System.out.println(System.currentTimeMillis()+" Pong received");
}
else
{
System.out.println(System.currentTimeMillis()+" Wrong answer");
out.close();
in.close();
clientSocket.close();
serverSocket.close();
break;
}
Thread.sleep(5000);
}
}
catch(Exception e)
{
System.err.println(System.currentTimeMillis()+" Unexpected Error");
}
}
});
t.start();
}
}
/* Client.java */
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
public class Client
{
private static final int PORT = 50000;
private static final String HOST = "localhost";
public static void main(String[] args) throws IOException
{
Socket socket = null;
try
{
socket = new Socket(HOST, PORT);
}
catch(Exception e)
{
System.err.println("Could not connect to "+HOST+":"+PORT);
System.exit(1);
}
final PrintWriter out = new PrintWriter(socket.getOutputStream(),true);
final BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
Thread t = new Thread(new Runnable()
{
public void run()
{
long start = System.currentTimeMillis();
while (true)
{
try
{
String input = in.readLine();
if (input != null)
{
System.out.println(System.currentTimeMillis() + " Server: " + input);
}
if (input.equals("Ping"))
{
if(System.currentTimeMillis()-start>30000)
{
out.println("Pon g");
System.out.println(System.currentTimeMillis() + " Client: Pon g");
break;
}
out.println("Pong");
System.out.println(System.currentTimeMillis() + " Client: Pong");
}
}
catch (IOException ioe)
{
//
}
}
}
});
t.start();
out.close();
in.close();
socket.close();
}
}
Output serwera:
Wating for connection.......... Client connected on port 50000 1308645130778 Ping sent 1308645130779 Pong received 1308645135779 Ping sent 1308645135779 Pong received 1308645140780 Ping sent 1308645140780 Pong received 1308645145780 Ping sent 1308645145780 Pong received 1308645150780 Ping sent 1308645150780 Pong received 1308645155781 Ping sent 1308645155781 Wrong answer
Output klienta:
1308645130778 Server: Ping 1308645130779 Client: Pong 1308645135779 Server: Ping 1308645135779 Client: Pong 1308645140780 Server: Ping 1308645140780 Client: Pong 1308645145780 Server: Ping 1308645145780 Client: Pong 1308645150780 Server: Ping 1308645150780 Client: Pong 1308645155781 Server: Ping 1308645155781 Client: Pon g
