Нулевая ошибка во время выполнения обработчика клиента в Java MultiThread ⇐ MySql

[Anonymous]

При тестировании этого кода я получил на одной стороне (клиент): ошибка во время выполнения: потоковой закрыт; в то время как на стороне сервера Следующая ошибка: ошибка при выполнении обработчика клиента: null; Код сервера следующим образом: < /p>

Код: Выделить всё

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.LinkedList;
import java.util.concurrent.CopyOnWriteArrayList;

public class ServerSocketChat {
private static final CopyOnWriteArrayList currentThreads = new CopyOnWriteArrayList();
private static final int PORT = 12345;
private static final int MAX_USERS = 10;

public static void main(String[] args) {
try (ServerSocket serverSocket = new ServerSocket(PORT)) {
System.out.println("Server sta ascoltando sulla porta " + PORT);

while (true) {
try {
Socket clientSocket = serverSocket.accept();

// Check max users before creating handler
if (currentThreads.size() >= MAX_USERS) {
System.out.println("Numero massimo di utenti raggiunto.  Connessione rifiutata.");
clientSocket.close();
continue;
}

System.out.println("Nuova connessione accettata " + clientSocket.getInetAddress());

// Create and start client handler
ClientHandler clientHandler = new ClientHandler(clientSocket);
Thread clientThread = new Thread(clientHandler);
currentThreads.add(clientThread);
clientThread.start();

// Clean up terminated threads
currentThreads.removeIf(thread -> !thread.isAlive());

} catch (IOException e) {
System.err.println("Errore nella gestione della connessione: " + e.getMessage());
}
}
} catch (IOException e) {
System.err.println("Errore critico nel server: " + e.getMessage());
}
}
}
< /code>
Между тем код обработчика клиента следующим: < /p>
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.LinkedList;

public class ClientHandler extends Thread {
private final Socket socket;
private Connection connection;

public ClientHandler(Socket socket) {
this.socket = socket;
try {
Class.forName("com.mysql.cj.jdbc.Driver");
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/DB_WhatApp_2_Fantini", "root", "");
} catch (ClassNotFoundException | SQLException e) {
System.err.println("Errore connessione db: " + e.getMessage());

return;
}
}

@Override
public void run() {
try (ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream());
ObjectInputStream in = new ObjectInputStream(socket.getInputStream())) {

String request;
while ((request = (String) in.readObject()) != null) {
if ("close".equals(request)) {
System.out.println("Client ha chiuso la connessione.");
break; // Esci dal ciclo se il client ha chiuso la connessione
}

String[] parts = request.split(",");
String action = parts[0];

switch (action) {
case "login" -> out.writeObject(login(parts[1], parts[2]));
case "TrovaChat" -> {
LinkedList emails = new LinkedList();
out.writeObject(getChat(parts[1], emails));
}
case "NuovaChat" -> out.writeObject(newChat(parts[1], parts[2]));
case "TrovaMessaggi" -> out.writeObject(getMessaggi(parts[1], parts[2]));
case "NuovoMessaggio" -> out.writeObject(newMessaggio(parts[1], parts[2], parts[3]));
default -> out.writeObject("Comando non valido");
}
}

} catch (ClassNotFoundException | IOException e) {
System.err.println("Errore durante l'esecuzione del client handler: " + e.getMessage());
} finally {
try {
if (connection != null) connection.close();
if (socket != null) socket.close();
} catch (SQLException | IOException e) {
System.err.println("Errore durante la chiusura delle risorse: " + e.getMessage());
}
}
}

private String login(String email, String password) {
String query = "SELECT COUNT(*) FROM UTENTE WHERE email = ? AND password = ?";
try (PreparedStatement stmt = connection.prepareStatement(query)) {
stmt.setString(1, email);
stmt.setString(2, password);
ResultSet rs = stmt.executeQuery();
rs.next();
return rs.getInt(1) > 0 ? "AUTH_SUCCESS"  : "AUTH_FAIL";
} catch (SQLException e) {
return "DB_ERROR: " + e.getMessage();
}
}

private String getMessaggi(String senderEmail, String recipientEmail) {
StringBuilder messages = new StringBuilder();
String updateQuery = "UPDATE MESSAGGIO SET flag_letto = TRUE WHERE " +
"ID_UTENTE_MITTENTE = (SELECT ID FROM UTENTE WHERE email = ?) AND " +
"ID_UTENTE_DESTINATARIO = (SELECT ID FROM UTENTE WHERE email = ?);";
try {
connection.setAutoCommit(false);
try (PreparedStatement updateStmt = connection.prepareStatement(updateQuery)) {
updateStmt.setString(1, recipientEmail);
updateStmt.setString(2, senderEmail);
updateStmt.executeUpdate();
}

String selectQuery = "SELECT data_ora, testo, CONCAT(s.COGNOME,' ',s.NOME) as sender " +
"FROM MESSAGGIO m LEFT JOIN UTENTE s ON m.ID_UTENTE_MITTENTE = s.ID " +
"LEFT JOIN UTENTE r ON m.ID_UTENTE_DESTINATARIO = r.ID " +
"WHERE (r.email = ? OR r.email = ?) AND (s.email = ? OR s.email = ?) " +
"ORDER BY data_ora ASC;";
try (PreparedStatement selectStmt = connection.prepareStatement(selectQuery)) {
selectStmt.setString(1, senderEmail);
selectStmt.setString(2, recipientEmail);
selectStmt.setString(3, senderEmail);
selectStmt.setString(4, recipientEmail);
ResultSet rs = selectStmt.executeQuery();

while (rs.next()) {
messages.append(rs.getTimestamp("data_ora"))
.append(" - ").append(rs.getString("sender")).append(": ")
.append(rs.getString("testo")).append("\n");
}
}
connection.commit();
return messages.toString();
} catch (SQLException e) {
try {
connection.rollback();
} catch (SQLException ex) {
System.err.println("Errore durante il rollback: " + ex.getMessage());
}
return "DB_ERROR: " + e.getMessage();
}
}

private String getChat(String email, LinkedList emails) {
StringBuilder chats = new StringBuilder();
String query = "SELECT DISTINCT u.nome, u.cognome, u.email FROM UTENTE u " +
"JOIN (SELECT m.ID, m.ID_UTENTE_MITTENTE, m.ID_UTENTE_DESTINATARIO FROM MESSAGGIO m " +
"WHERE m.ID_UTENTE_MITTENTE = (SELECT ID FROM UTENTE WHERE email = ?) " +
"OR m.ID_UTENTE_DESTINATARIO = (SELECT ID FROM UTENTE WHERE email = ?)) AS sub " +
"ON u.ID = sub.ID_UTENTE_MITTENTE OR u.ID = sub.ID_UTENTE_DESTINATARIO WHERE u.email != ?;";
try (PreparedStatement stmt = connection.prepareStatement(query)) {
stmt.setString(1, email);
stmt.setString(2, email);
stmt.setString(3, email);
ResultSet rs = stmt.executeQuery();
int index = 1;
while (rs.next()) {
chats.append(index++).append(" - Apri chat con ").append(rs.getString("cognome")).append(" ").append(rs.getString("nome")).append(" ").append(rs.getString("email")).append("\n");
emails.add(rs.getString("email"));
}
return chats.toString();
} catch (SQLException e) {
return "DB_ERROR: "  + e.getMessage();
}
}

private String newChat(String senderEmail, String recipientEmail) {
try {
connection.setAutoCommit(false);
int recipientId = getUserId(recipientEmail);
if (recipientId == -1) return "Utente non trovato";

int senderId = getUserId(senderEmail);
if (senderId == -1) return "Utente non trovato";

if (chatExists(senderEmail, recipientEmail)) return "Chat gia' esistente";

String createChat = "INSERT INTO MESSAGGIO (ID_UTENTE_MITTENTE, ID_UTENTE_DESTINATARIO, DATA_ORA, TESTO) VALUES (?, ?, NOW(), '');";
try (PreparedStatement stmt = connection.prepareStatement(createChat)) {
stmt.setInt(1, senderId);
stmt.setInt(2, recipientId);
stmt.executeUpdate();
}
connection.commit();
return "Chat creata";
} catch (SQLException e) {
try {
connection.rollback();
} catch (SQLException ex) {
System.err.println("Errore durante il rollback: " + ex.getMessage());
}
return "DB_ERROR: " + e.getMessage();
}
}

private int getUserId(String email) throws SQLException {
String query = "SELECT ID FROM UTENTE WHERE email = ?";
try (PreparedStatement stmt = connection.prepareStatement(query)) {
stmt.setString(1, email);
ResultSet rs = stmt.executeQuery();
return rs.next() ? rs.getInt("ID") : -1;
}
}

private boolean chatExists(String senderEmail, String recipientEmail) throws SQLException {
String query = "SELECT m.ID FROM MESSAGGIO m " +
"JOIN UTENTE s ON m.ID_UTENTE_MITTENTE = s.ID " +
"JOIN UTENTE r ON m.ID_UTENTE_DESTINATARIO = r.ID " +
"WHERE (s.email = ? AND r.email = ?) OR (s.email = ? AND r.email = ?);";
try (PreparedStatement stmt = connection.prepareStatement(query)) {
stmt.setString(1, senderEmail);
stmt.setString(2, recipientEmail);
stmt.setString(3, recipientEmail);
stmt.setString(4, senderEmail);
ResultSet rs = stmt.executeQuery();
return rs.next();
}
}

private String newMessaggio(String senderEmail, String recipientEmail, String message) {
try {
connection.setAutoCommit(false);
int recipientId = getUserId(recipientEmail);
if (recipientId == -1) return "USER_NOT_FOUND";

int senderId = getUserId(senderEmail);
if (senderId == -1) return "USER_NOT_FOUND";

String insertMessage = "INSERT INTO MESSAGGIO (ID_UTENTE_MITTENTE, ID_UTENTE_DESTINATARIO, data_ora, testo, flag_letto) VALUES (?, ?, NOW(), ?, FALSE)";
try (PreparedStatement stmt = connection.prepareStatement(insertMessage)) {
stmt.setInt(1, senderId);
stmt.setInt(2, recipientId);
stmt.setString(3, message);
stmt.executeUpdate();
}
connection.commit();
return "MESSAGE_INSERTED";
} catch (SQLException e) {
try {
connection.rollback();
} catch (SQLException ex) {
System.err.println("Errore durante il rollback: " + ex.getMessage());
}
return "DB_ERROR: " + e.getMessage();
}
}
}

Пожалуйста, я работал над этими кодами в течение 3 недель.

Подробнее здесь: https://stackoverflow.com/questions/794 ... ultithread