Esercizi sul Networking in Java
Codegrind Team•Jul 12 2024
Ecco degli esercizi con soluzione per praticare il networking in Java.
Esercizio 1: Creazione di un Client e Server Semplice
Creare un semplice client e server TCP dove il client invia un messaggio al server e il server risponde.
Server.java:
import java.io.*;
import java.net.*;
public class Server {
public static void main(String[] args) {
try (ServerSocket serverSocket = new ServerSocket(1234)) {
System.out.println("Server in attesa di connessione...");
Socket socket = serverSocket.accept();
System.out.println("Client connesso.");
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
String messaggio = in.readLine();
System.out.println("Messaggio ricevuto dal client: " + messaggio);
out.println("Messaggio ricevuto: " + messaggio);
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Client.java:
import java.io.*;
import java.net.*;
public class Client {
public static void main(String[] args) {
try (Socket socket = new Socket("localhost", 1234)) {
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out.println("Ciao, Server!");
String risposta = in.readLine();
System.out.println("Risposta dal server: " + risposta);
} catch (IOException e) {
e.printStackTrace();
}
}
}
Esercizio 2: Trasferimento di File
Creare un client e un server TCP che permettano il trasferimento di un file di testo dal client al server.
Server.java:
import java.io.*;
import java.net.*;
public class FileServer {
public static void main(String[] args) {
try (ServerSocket serverSocket = new ServerSocket(1234)) {
System.out.println("Server in attesa di connessione...");
Socket socket = serverSocket.accept();
System.out.println("Client connesso.");
InputStream inputStream = socket.getInputStream();
FileOutputStream fileOutputStream = new FileOutputStream("ricevuto.txt");
byte[] buffer = new byte[4096];
int bytesRead;
while ((bytesRead = inputStream.read(buffer)) != -1) {
fileOutputStream.write(buffer, 0, bytesRead);
}
fileOutputStream.close();
socket.close();
System.out.println("File ricevuto con successo.");
} catch (IOException e) {
e.printStackTrace();
}
}
}
Client.java:
import java.io.*;
import java.net.*;
public class FileClient {
public static void main(String[] args) {
try (Socket socket = new Socket("localhost", 1234)) {
FileInputStream fileInputStream = new FileInputStream("da_inviare.txt");
OutputStream outputStream = socket.getOutputStream();
byte[] buffer = new byte[4096];
int bytesRead;
while ((bytesRead = fileInputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
fileInputStream.close();
socket.close();
System.out.println("File inviato con successo.");
} catch (IOException e) {
e.printStackTrace();
}
}
}
Esercizio 3: Server HTTP Semplice
Creare un semplice server HTTP che risponda con un messaggio di benvenuto a ogni richiesta GET.
import java.io.*;
import java.net.*;
public class SimpleHttpServer {
public static void main(String[] args) {
try (ServerSocket serverSocket = new ServerSocket(8080)) {
System.out.println("Server HTTP in attesa di connessione...");
while (true) {
try (Socket socket = serverSocket.accept()) {
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter out = new PrintWriter(socket.getOutputStream());
String line;
while ((line = in.readLine()) != null && !line.isEmpty()) {
System.out.println(line);
}
String httpResponse = "HTTP/1.1 200 OK\r\n\r\nBenvenuto sul mio server HTTP!";
out.write(httpResponse);
out.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
Esercizio 4: UDP Client e Server
Creare un client e un server UDP dove il client invia un messaggio al server e il server risponde.
Server.java:
import java.net.*;
public class UdpServer {
public static void main(String[] args) {
try (DatagramSocket socket = new DatagramSocket(1234)) {
byte[] buffer = new byte[1024];
DatagramPacket request = new DatagramPacket(buffer, buffer.length);
System.out.println("Server UDP in attesa di pacchetti...");
socket.receive(request);
String messaggio = new String(request.getData(), 0, request.getLength());
System.out.println("Messaggio ricevuto dal client: " + messaggio);
String risposta = "Messaggio ricevuto";
byte[] bufferRisposta = risposta.getBytes();
DatagramPacket response = new DatagramPacket(bufferRisposta, bufferRisposta.length, request.getAddress(), request.getPort());
socket.send(response);
System.out.println("Risposta inviata al client.");
} catch (Exception e) {
e.printStackTrace();
}
}
}
Client.java:
import java.net.*;
public class UdpClient {
public static void main(String[] args) {
try (DatagramSocket socket = new DatagramSocket()) {
String messaggio = "Ciao, Server UDP!";
byte[] buffer = messaggio.getBytes();
InetAddress address = InetAddress.getByName("localhost");
DatagramPacket packet = new DatagramPacket(buffer, buffer.length, address, 1234);
socket.send(packet);
byte[] bufferRisposta = new byte[1024];
DatagramPacket response = new DatagramPacket(bufferRisposta, bufferRisposta.length);
socket.receive(response);
String risposta = new String(response.getData(), 0, response.getLength());
System.out.println("Risposta dal server: " + risposta);
} catch (Exception e) {
e.printStackTrace();
}
}
}
Esercizio 5: Multithreaded Server
Creare un server TCP multithreaded che possa gestire più connessioni client contemporaneamente.
Server.java:
import java.io.*;
import java.net.*;
public class MultithreadedServer {
public static void main(String[] args) {
try (ServerSocket serverSocket = new ServerSocket(1234)) {
System.out.println("Server in attesa di connessione...");
while (true) {
Socket socket = serverSocket.accept();
System.out.println("Client connesso.");
new ClientHandler(socket).start();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
class ClientHandler extends Thread {
private final Socket socket;
public ClientHandler(Socket socket) {
this.socket = socket;
}
@Override
public void run() {
try {
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
String messaggio;
while ((messaggio = in.readLine()) != null) {
System.out.println("Messaggio ricevuto: " + messaggio);
out.println("Echo: " + messaggio);
}
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Client.java:
import java.io.*;
import java.net.*;
public class MultithreadedClient {
public static void main(String[] args) {
try (Socket socket = new Socket("localhost", 1234)) {
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out.println("Ciao, Server!");
String risposta = in.readLine();
System.out.println("Risposta dal server: " + risposta);
} catch (IOException e) {
e.printStackTrace();
}
}
}
Esercizio 6: Chat Room di Base
Creare una semplice chat room usando TCP dove i messaggi inviati da un client sono trasmessi a tutti gli altri client connessi.
Server.java:
import java.io.*;
import java.net.*;
import java.util.*;
public class ChatServer {
private static Set<ClientHandler> clientHandlers = new HashSet<>();
public static void main(String[] args) {
try (ServerSocket serverSocket = new ServerSocket(1234)) {
System.out.println("Chat server in attesa di connessioni...");
while (true) {
Socket socket = serverSocket.accept();
System.out.println("Client connesso.");
ClientHandler clientHandler = new ClientHandler(socket);
clientHandlers.add(clientHandler);
clientHandler.start();
}
} catch (IOException e) {
e.printStackTrace();
}
}
static void broadcast(String message, ClientHandler sender) {
for (ClientHandler clientHandler : clientHandlers) {
if (clientHandler != sender) {
clientHandler.sendMessage(message);
}
}
}
static void removeClient(ClientHandler clientHandler) {
clientHandlers.remove(clientHandler);
}
}
class ClientHandler extends Thread {
private Socket socket;
private PrintWriter out;
private BufferedReader in;
public ClientHandler(Socket socket) {
this.socket = socket;
}
@Override
public void run() {
try {
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out = new PrintWriter(socket.getOutputStream(), true);
String message;
while ((message = in.readLine()) != null) {
System.out.println("Messaggio ricevuto: " + message);
ChatServer.broadcast(message, this);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
ChatServer.removeClient(this);
}
}
void sendMessage(String message) {
out.println(message);
}
}
Client.java:
import java.io.*;
import java.net.*;
public class ChatClient {
public static void main(String[] args) {
try (Socket socket = new Socket("localhost", 1234)) {
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
new Thread(() -> {
String response;
try {
while ((response = in.readLine()) != null) {
System.out.println("Messaggio dal server: " + response);
}
} catch (IOException e) {
e.printStackTrace();
}
}).start();
String userInput;
while ((userInput = stdIn.readLine()) != null) {
out.println(userInput);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}