Проблема многопоточности с групповым чатом в сокетах Java

Question

Я обнаружил несколько случаев моей проблемы, но, к сожалению, не могу ее исправить после многих часов.В основном у меня есть приложение группового чата Socket, которое позволяет клиентам входить в систему, сервер использует базу данных для проверки входа в систему, а затем либо позволяет клиенту перейти на страницу чата, либо нет.После входа в систему нажимается кнопка «Подключить», чтобы инициализировать сокетное соединение для чата.Я добрался до стадии, когда у меня могло быть несколько клиентов, и каждый мог отправить сообщение, оно было бы принято сервером и отправлено всем клиентам, но другие клиенты могли прочитать его только при нажатии кнопки «Отправить».С тех пор я попробовал много способов заставить его работать синхронизированным, но теперь я вернулся к точке, где сервер не будет возвращать сообщения обратно.

Я хотел бы получить совет о том, как изменить сервер, чтобы получать сообщения, полученные от клиентов, и передавать их всем клиентам.

PS Это мой первый пост, заранее спасибо.

Код сервера и обработчика ----------------------

public class ServerHandler extends JFrame {

private static final long serialVersionUID = 1L;
private JPanel contentPane;
static JTextField tfSend;
public static JTextArea textArea;
private JScrollPane scrollPane;
static JButton btnSend;
private JButton btnSettings;




/**
 * Launch the application.
 * @throws IOException 
 */
public static void main(String[] args) throws IOException {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                ServerHandler frame = new ServerHandler();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });

     // server is listening on port 8000 
    ServerSocket ss = new ServerSocket(8000); 

      while (true)  
     { 
        Socket s = null; 

         try 
         { 
           //socket object to receive incoming client requests 
             s = ss.accept(); 
               textArea.setText(textArea.getText() + "\nA new client connected : " + s); 

              //obtaining input and out streams 

            ObjectOutputStream oos = new ObjectOutputStream(s.getOutputStream()); 
            ObjectInputStream ois = new ObjectInputStream(s.getInputStream());
            DataOutputStream dos = new DataOutputStream(s.getOutputStream()); 
            DataInputStream dis = new DataInputStream(s.getInputStream());
            textArea.setText(textArea.getText() + "\nAssigning new thread for this client"); 


             // create a new thread object 
             ClientHandler t = new ClientHandler(s, ois, oos, dos,dis);                 
              //Invoking the start() method 
             t.start();                  

         } 
         catch (Exception e){ 
           s.close(); 
            ss.close();
             e.printStackTrace(); 
         } 
     } 
} 


public ServerHandler() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 700, 500);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    contentPane.setBackground(Color.LIGHT_GRAY);
    setContentPane(contentPane);
    contentPane.setLayout(null);

    btnSend = new JButton("Send");
    btnSend.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
    btnSend.setBounds(542, 404, 117, 29);
    contentPane.add(btnSend);

    btnSettings = new JButton("Settings");
    btnSettings.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
    btnSettings.setBounds(542, 30, 117, 29);
    contentPane.add(btnSettings);

    tfSend = new JTextField();
    tfSend.setBounds(45, 404, 490, 26);
    contentPane.add(tfSend);
    tfSend.setColumns(10);
    tfSend.setEditable(false);


    textArea = new JTextArea();
    scrollPane = new JScrollPane(textArea);
    scrollPane.setLocation(47, 71);
    scrollPane.setAutoscrolls(true);
    scrollPane.setSize(612,322);
    contentPane.add(scrollPane);
    textArea.setEditable(false);


    JLabel lblNewLabel = new JLabel("");
    lblNewLabel.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
    lblNewLabel.setBounds(26, 23, 652, 429);
    contentPane.add(lblNewLabel);
}  
}
class ClientHandler extends Thread  { 
    //thread conns
    private ObjectInputStream ois; 
    private ObjectOutputStream oos; 
    private DataOutputStream dos;
    private DataInputStream dis;
    private Socket s;

    //database conns
    static Connection c;
    static Statement stmt;
    static Connection c1;
    static Statement stmt1;     
    static Connection c2;
    static Statement stmt2;


    public ClientHandler(Socket s, ObjectInputStream ois, ObjectOutputStream oos, DataOutputStream dos2,  DataInputStream dis2) {
        this.s = s;
        this.ois = ois;
        this.oos = oos;
        this.dos = dos2;
        this.dis = dis2;
    }


    @Override
    public void run()  
    {   
        try {
            System.out.println("running");
            checkUTF();
        } catch (IOException e1) {
            e1.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
}


    public void checkUTF() throws IOException, SQLException {
        while(true) {
            String check = null;
            check = dis.readUTF();
            System.out.println("check");
            if (check!= null) {
                System.out.println("switching");
                try {       
                    switch(check) {
                    case "chat":
                        System.out.println("chatting");
                        chat();
                    case "Login":
                        try {
                            System.out.println("checking login");
                            checkLogin();
                        } catch (SQLException e1) {
                            e1.printStackTrace();
                        }
                    }}finally { 
                        System.out.println("ending");
                        close();
                    }       
            }else {

            }
        }
    }

    public void chat() throws IOException {

        dos.writeUTF("chat");
        dos.flush();
        ServerHandler.tfSend.setEditable(true);

        while(s.isClosed()==false) {
            String check = null;
            check = dis.readUTF();

            if (check!= null) {
                if(check.equals("close")){
                    dos.writeUTF("close");
                    break;
                }else{
                    dos.writeUTF(check);
                }
            }
        }
        }



public void close() throws IOException {
    dos.close();
    dis.close();
    oos.close();
    ois.close();
    s.close();
}

public void checkLogin() throws SQLException {
    ClientStuff.LoginObject login = null;

        System.out.println("here");
        try {
            login = (LoginObject) ois.readObject();
            System.out.println(login.getName() + login.getPassword());
            String username = login.getName().trim();
            String password = login.getPassword().trim();

                if((checkLoginDetails(username,password))==true) {
                    closeDatabase();
                    String status = "Found";
                    dos.writeUTF(status);
                    dos.flush();
                    System.out.println("ending2");

                }else {
                    closeDatabase();
                    String status = "Not Found";
                    dos.writeUTF(status);
                    dos.flush();
                    System.out.println("ending3");
                    close();
                }                                                   
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
}



public static boolean checkLoginDetails(String username, String password) throws SQLException {

    startDatabaseConnections();
    stmt2 = c2.createStatement();
    ResultSet rs = stmt2.executeQuery("SELECT * FROM CLIENTINFO WHERE USERNAME = '"+username+"' AND PASSWORD = '"+password+"';");
    while ( rs.next() ) {            
        return true;
    }

    rs.close();
    return false;
}


public static void startDatabaseConnections() {

    try {
        Class.forName("org.sqlite.JDBC");
        c = DriverManager.getConnection("jdbc:sqlite:ServerInfo");
        System.out.println("Opened database successfully");
    } catch ( Exception e ) {
        System.err.println( e.getClass().getName() + ": " + e.getMessage() );
        System.exit(0);
    }

    try {
        Class.forName("org.sqlite.JDBC");
        c1 = DriverManager.getConnection("jdbc:sqlite:ClientConvo");
        System.out.println("Opened database successfully");
    } catch ( Exception e ) {
        System.err.println( e.getClass().getName() + ": " + e.getMessage() );
        System.exit(0);
    }
    try {
        Class.forName("org.sqlite.JDBC");
        c2 = DriverManager.getConnection("jdbc:sqlite:ClientInfo");
        System.out.println("Opened database successfully");
    } catch ( Exception e ) {
        System.err.println( e.getClass().getName() + ": " + e.getMessage() );
        System.exit(0);
    }
}

public static void closeDatabase() throws SQLException {
    c.close();
    c1.close();
    c2.close();
    System.out.println("Databases Closed");
}

}

Код входа клиента --------------

 public class UserLogin extends JFrame {

/**
 * 
 */
private static final long serialVersionUID = 1L;

/**
 * 
 */

static UserLogin frame;

private JPanel contentPane;
private static JTextField tfUsername;
private  static JTextField tfPassword;
static boolean yes = false;

static JButton btnNewUser = new JButton("New User");
static JButton btnLogin = new JButton("Login");

static Socket login = new Socket();
private static String serverIP = "127.0.0.1";
static ObjectOutputStream oos;
static ObjectInputStream ois;
static DataOutputStream dos;
static DataInputStream dis;

static String status = null;


/**
 * Launch the application.
 * @throws IOException 
 * @throws UnknownHostException 
 * @throws ClassNotFoundException 
 */
public static void main(String[] args) throws UnknownHostException, IOException, ClassNotFoundException {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                frame = new UserLogin();
                if(frame.isVisible()==false) {
                    frame.setVisible(true);
                }

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });

}
public void foundUser(String status) {
    if (status.equals("Found")) {
    frame.setVisible(false);
    dispose();
    new UserChat().setVisible(true);
}else if(status.equals("Not Found")) {
    close();
    tfUsername.setText("Not Found");
    tfPassword.setText("Not Found");
}
}

public void close(){
    System.out.println("closing");
    try {
        login.close();
        dos.close();
        dis.close();
        oos.close();
        ois.close(); 
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public void connectServer() throws IOException {
    System.out.println("start stream setup");
    login = new Socket(InetAddress.getByName(serverIP), 8000);
    }

public void setupStreams() throws IOException {
    System.out.println("start stream setup 2");
    oos = new ObjectOutputStream(login.getOutputStream());      
    System.out.println("obj output stream setup");
    ois = new ObjectInputStream(login.getInputStream());
    System.out.println("obj input stream setup");
    dos = new DataOutputStream(login.getOutputStream()); 
    System.out.println("data output stream setup");
    dis = new DataInputStream(login.getInputStream());  
    System.out.println("data input stream setup");
}



/**
 * Create the frame.
 * @throws IOException 
 */
public UserLogin() throws IOException {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 700, 500);
    contentPane = new JPanel();
    contentPane.setBackground(Color.LIGHT_GRAY);
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(null);

    btnNewUser.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
    btnNewUser.setBounds(373, 294, 117, 29);
    contentPane.add(btnNewUser);

    btnLogin.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
    btnLogin.setBounds(373, 253, 117, 29);
    contentPane.add(btnLogin);

    tfUsername = new JTextField();
    tfUsername.setBounds(255, 175, 235, 26);
    contentPane.add(tfUsername);
    tfUsername.setColumns(10);

    tfPassword = new JTextField();
    tfPassword.setColumns(10);
    tfPassword.setBounds(255, 213, 235, 26);
    contentPane.add(tfPassword);

    JLabel lblUsername = new JLabel("Username");
    lblUsername.setBounds(127, 180, 104, 16);
    contentPane.add(lblUsername);

    JLabel lblPassword = new JLabel("Password");
    lblPassword.setBounds(127, 218, 104, 16);
    contentPane.add(lblPassword);

    JLabel lblNewLabel = new JLabel("");
    lblNewLabel.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
    lblNewLabel.setBounds(26, 23, 646, 429);
    contentPane.add(lblNewLabel);

    btnNewUser.addActionListener(
            new ActionListener(){
                public void actionPerformed(ActionEvent event){
                    new UserReg().setVisible(true);
                }
            }
            );

    btnLogin.addActionListener(
            new ActionListener(){
                public void actionPerformed(ActionEvent event){
                    LoginObject userLogin = new LoginObject(tfUsername.getText(),tfPassword.getText());
                    System.out.println(userLogin.getName() + userLogin.getPassword());
                    try {
                        connectServer();
                        setupStreams();
                        dos.writeUTF("Login");
                        dos.flush();
                        System.out.println("login");
                        oos.writeObject(userLogin);
                        oos.flush();
                        System.out.println("userlogin");
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    String status = null;
                    try {
                        status = dis.readUTF();
                        System.out.println(status);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    System.out.println(status);
                    foundUser(status);
                    }
                }
            );
}}

Код чата клиента ---------

   public class UserChat extends JFrame {

/**
 * 
 */
private static final long serialVersionUID = 1L;
private JPanel contentPane;
private static  JTextField tfSend;
private static JTextArea textArea;
private JScrollPane scrollPane;
private static JButton btnSend;
private JButton btnSettings;
private JButton btnLogout;
private JButton btnGetChat;
String messageIn = "";      


private static Socket login = new Socket();
private static String serverIP = "127.0.0.1";
static ObjectOutputStream oos;
static ObjectInputStream ois;
static DataOutputStream dos;
static DataInputStream dis;

static String status = null;
private JButton btnConnect;



/**
 * Launch the application.
 * @throws IOException 
 */
public static void main(String[] args) throws IOException {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            UserChat frame = new UserChat();
            if(frame.isVisible()==false) {
                frame.setVisible(true);
            }
        }
    });

    System.out.println("mainnn");
    }

public static void connectServer() throws IOException {
    textArea.setText(textArea.getText()+"start stream setup\n");
    login = new Socket(InetAddress.getByName(serverIP), 8000);
    textArea.setText(textArea.getText()+"start stream setup 2\n");
    oos = new ObjectOutputStream(login.getOutputStream());      
    textArea.setText(textArea.getText()+"obj output stream setup\n");
    ois = new ObjectInputStream(login.getInputStream());
    textArea.setText(textArea.getText()+"obj input stream setup\n");
    dos = new DataOutputStream(login.getOutputStream()); 
    textArea.setText(textArea.getText()+"data output stream setup\n");
    dis = new DataInputStream(login.getInputStream());  
    textArea.setText(textArea.getText()+"data input stream setup\n");
    }


public static void whileChatting() throws IOException {
    tfSend.setEditable(true);

            if(login.isClosed()==false) {
                btnSend.addActionListener(
                        new ActionListener(){
                            public void actionPerformed(ActionEvent event){
                                String sendText = "Client - ";
                                sendText += tfSend.getText();
                                try {
                                    dos.writeUTF(sendText);
                                    dos.flush();

                                } catch (IOException e) {
                                    e.printStackTrace();
                                }
                                tfSend.setText("");
                            }
                        }
                        );

                Thread t = new MsgHandler(login, ois, oos, dis,dos, textArea); 

                t.start(); 
            }
}
/**
 * Create the frame.
 */
public UserChat() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 700, 500);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    contentPane.setBackground(Color.LIGHT_GRAY);
    setContentPane(contentPane);
    contentPane.setLayout(null);

    btnSend = new JButton("Send");
    btnSend.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
    btnSend.setBounds(542, 404, 117, 29);
    contentPane.add(btnSend);

    btnConnect = new JButton("Connect");
    btnConnect.setBounds(165, 31, 117, 29);
    contentPane.add(btnConnect);

    btnSettings = new JButton("Settings");
    btnSettings.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
    btnSettings.setBounds(542, 30, 117, 29);
    contentPane.add(btnSettings);

    btnLogout = new JButton("Logout");
    btnLogout.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
    btnLogout.setBounds(37, 30, 117, 29);
    contentPane.add(btnLogout);

    btnGetChat = new JButton("Get Chat");
    btnGetChat.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
    btnGetChat.setBounds(417, 30, 117, 29);
    contentPane.add(btnGetChat);

    tfSend = new JTextField();
    tfSend.setBounds(45, 404, 490, 26);
    contentPane.add(tfSend);
    tfSend.setColumns(10);
    tfSend.setEditable(false);

    textArea = new JTextArea();
    scrollPane = new JScrollPane(textArea);
    scrollPane.setLocation(47, 71);
    scrollPane.setAutoscrolls(true);
    scrollPane.setSize(612,322);
    contentPane.add(scrollPane);
    textArea.setEditable(false);

    JLabel lblNewLabel = new JLabel("");
    lblNewLabel.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
    lblNewLabel.setBounds(26, 23, 652, 429);
    contentPane.add(lblNewLabel);

    btnLogout.addActionListener(
            new ActionListener(){
                public void actionPerformed(ActionEvent event){
                    try {
                        dos.writeUTF("logout");
                        dos.flush();
                        System.out.println("Servers Closed");   
                        dispose();
                        setVisible(false);
                        UserLogin.main(null);
                    } catch (IOException | ClassNotFoundException e) {
                        e.printStackTrace();
                    }

                }
            }
            );
    btnConnect.addActionListener(
            new ActionListener(){
                public void actionPerformed(ActionEvent event){

                        try {
                            connectServer();
                            dos.writeUTF("chat");
                            dos.flush();
                            String chat = dis.readUTF();
                            System.out.println(chat);
                                if(chat.equals("chat")) {
                                    System.out.println(chat);
                                    btnConnect.setVisible(false);
                                    whileChatting();
                                }
                        } catch (IOException e) {
                            e.printStackTrace();
                            System.out.println("Here");
                        }

                    }
                }
            );

    }
  }



 class MsgHandler extends Thread{
final ObjectInputStream ois; 
final ObjectOutputStream oos; 
final Socket s; 
DataOutputStream dos;
DataInputStream dis;
JTextArea textArea;

public MsgHandler(Socket s, ObjectInputStream ois, ObjectOutputStream oos, DataInputStream dis2, DataOutputStream dos2,
        JTextArea textArea){
    this.s = s; 
    this.ois = ois; 
    this.oos = oos; 
    this.dis = dis2; 
    this.dos = dos2; 
    this.textArea = textArea;
}

public void run(){

    try {
        checkUTF();
    } catch (IOException e1) {
        e1.printStackTrace();
    }
}


public void checkUTF() throws IOException  {
    System.out.println("running to listen");
    while(s.isClosed()==false) {
        String check = null;
        check = dis.readLine();
        if (check!= null) {
            if(check.equals("close")){
                close();
                break;
            }else{
                textArea.append("\n"+check);
                System.out.println("receive message from the server");
            }
        }
    }
}

public void close(){
    System.out.println("closing");
    try {
        s.close();
        dos.close();
        dis.close();
        oos.close();
        ois.close(); 
    } catch (IOException e) {
        e.printStackTrace();
    }
}

}