Tentando De novo com Sockets! (ObjectOutputStream$BlockDataOutputStream.drain)

Programação Java
#1

Gente, estou quase conseguindo transferir uma string do cliente para o servidor mas esta dando um erro que nao consigo resolver:
Podem me ajudar?

[quote]run:
Servidor ouvindo a porta 12345
Cliente conectado!
Exception in thread “AWT-EventQueue-0” java.lang.NullPointerException
at java.io.ObjectOutputStream$BlockDataOutputStream.drain(ObjectOutputStream.java:1847)
at java.io.ObjectOutputStream$BlockDataOutputStream.setBlockDataMode(ObjectOutputStream.java:1756)
at java.io.ObjectOutputStream.(ObjectOutputStream.java:230)
at sendreceive.Transport.EnviarMsg(Transport.java:52)
at sendreceive.InterfaceA.jButton4ActionPerformed(InterfaceA.java:112)
at sendreceive.InterfaceA.access$300(InterfaceA.java:10)
at sendreceive.InterfaceA$4.actionPerformed(InterfaceA.java:57)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.java:6288)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
at java.awt.Component.processEvent(Component.java:6053)
at java.awt.Container.processEvent(Container.java:2041)
at java.awt.Component.dispatchEventImpl(Component.java:4651)
at java.awt.Container.dispatchEventImpl(Container.java:2099)
at java.awt.Component.dispatchEvent(Component.java:4481)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4577)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
at java.awt.Container.dispatchEventImpl(Container.java:2085)
at java.awt.Window.dispatchEventImpl(Window.java:2478)
at java.awt.Component.dispatchEvent(Component.java:4481)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:643)
at java.awt.EventQueue.access$000(EventQueue.java:84)
at java.awt.EventQueue$1.run(EventQueue.java:602)
at java.awt.EventQueue$1.run(EventQueue.java:600)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
at java.awt.EventQueue$2.run(EventQueue.java:616)
at java.awt.EventQueue$2.run(EventQueue.java:614)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:613)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
CONSTRUÍDO COM SUCESSO (tempo total: 8 segundos)
[/quote]

package sendreceive;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.PrintStream;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;

/**
 *
 * @author André Vinícius Lopes
 */ 
   
public class Transport {

    public Transport() {
    
    }
    
    public static void IniciarCliente()
    {
        try {
        
       
        Socket cliente = new Socket("localhost",12345);
        Receiver.AceitarConn();  
        System.out.println("Cliente conectado!");
         
        } catch (UnknownHostException ex) {
           
            JOptionPane.showMessageDialog(null, ex.getMessage());
           
            } catch (IOException ex) {
                  JOptionPane.showMessageDialog(null, ex.getMessage());
            }
     }
    
    public static void EnviarMsg() throws IOException
    {
        ObjectOutputStream x = null;
        String a = null;
        a = JOptionPane.showInputDialog(null,"Escreva uma mensagem");
        
        try {
            x = new ObjectOutputStream(null);
        } catch (IOException ex) {
            JOptionPane.showMessageDialog(null, ex.getMessage());
        }
        
        x.writeBytes(a);
        Receiver.MsgServidor(x);
        
        
        
    }
    
    
    
   
    
}
package sendreceive;

import java.io.BufferedReader;
import java.io.*;
import java.net.*;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;

  
public class Receiver {
    private static ServerSocket x;

    public Receiver() {
        
    }

    public static void IniciarServidor() throws IOException
    {
        
            ServerSocket servidor = new ServerSocket(12345);
            System.out.println("Servidor ouvindo a porta 12345");
            x = servidor;
            
            
        
     }
       
    public static void AceitarConn() throws IOException
    {
         Socket cliente = x.accept();
    }
    
    public static void MsgServidor(ObjectOutputStream x) throws IOException 
    {
       
        ObjectInputStream entrada = new ObjectInputStream(null);  
        String a = x.toString();
        JOptionPane.showMessageDialog(null,"Msg Recebida:" + a);
        
        
        
    }
    
    
    
}

package sendreceive;

import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;


public class InterfaceA extends javax.swing.JFrame {

    /** Creates new form InterfaceA */
    public InterfaceA() {
        initComponents();
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jButton1 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();
        jButton3 = new javax.swing.JButton();
        jButton4 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jButton1.setText("Iniciar Servidor");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jButton2.setText("Iniciar Cliente");
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });

        jButton3.setText("Ler Mensagem");
        jButton3.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton3ActionPerformed(evt);
            }
        });

        jButton4.setText("Enviar Mensagem");
        jButton4.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton4ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jButton1)
                    .addComponent(jButton4))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jButton3)
                    .addComponent(jButton2))
                .addContainerGap(166, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(24, 24, 24)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton1)
                    .addComponent(jButton2))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton3)
                    .addComponent(jButton4))
                .addContainerGap(212, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                        

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        try {
            Receiver.IniciarServidor();
        } catch (IOException ex) {
            Logger.getLogger(InterfaceA.class.getName()).log(Level.SEVERE, null, ex);
        }
}                                        

private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                         
  
    // TODO add your handling code here:
}                                        

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
Transport.IniciarCliente();       
}                                        

    private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        try {
            Transport.EnviarMsg();
        } catch (IOException ex) {
           JOptionPane.showMessageDialog(null, ex.getMessage());
        }
    }                                        

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(InterfaceA.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(InterfaceA.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(InterfaceA.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(InterfaceA.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new InterfaceA().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JButton jButton3;
    private javax.swing.JButton jButton4;
    // End of variables declaration                   
}
#2

Gente, consegui fazer eles se comunicarem mas a mensagem que eu escrevo retorna um valor estranho… acho q é em hexadecimal… não estou conseguindo ler ele com object output;
Segue os novos códigos!

Alguém me ajuda , por favor

package sendreceive;

import java.io.BufferedReader;
import java.io.*;
import java.net.*;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;

  
public class Receiver {
    private static ServerSocket x;

    public Receiver() {
        
    }

    public static void IniciarServidor() throws IOException
    {
        
            ServerSocket servidor = new ServerSocket(12345);
            System.out.println("Servidor ouvindo a porta 12345");
            x = servidor;
           
            
            
        
     }
       
    public static void AceitarConn() throws IOException
    {
         Socket cliente = x.accept();
    }
    
    public static void MsgServidor(ObjectOutputStream x) throws IOException 
    {
        
        String a = x.toString();
        String b = null;
        //
       
        //
        JOptionPane.showMessageDialog(null,"Msg Recebida:" + a);
        System.out.println(a);
        
        
        
    }
    
    
    
}
package sendreceive;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.PrintStream;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;

/**
 *
 * @author André Vinícius Lopes
 */ 
   
public class Transport {

    public Transport() {
    
    }
    
    public static void IniciarCliente()
    {
        try {
        
       
        Socket cliente = new Socket("localhost",12345);
        Receiver.AceitarConn();  
        System.out.println("Cliente conectado!");
         
        } catch (UnknownHostException ex) {
           
            JOptionPane.showMessageDialog(null, ex.getMessage());
           
            } catch (IOException ex) {
                  JOptionPane.showMessageDialog(null, ex.getMessage());
            }
     }
    
    public static void EnviarMsg() throws IOException
    {
        ObjectOutputStream x = null;
        String a = null;
        a = JOptionPane.showInputDialog(null,"Escreva uma mensagem");
         Socket cliente = new Socket("localhost",12345);
        try {
            x = new ObjectOutputStream(cliente.getOutputStream());
        } catch (IOException ex) {
            JOptionPane.showMessageDialog(null, ex.getMessage());
        }
        
        //x.writeBytes(a);
       
        //x.writeChars(a);
        
        x.writeObject(a);
        x.close();
        Receiver.MsgServidor(x);
        
        
        
    }
    
    
    
   
    
}
package sendreceive;

import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;


public class InterfaceA extends javax.swing.JFrame {

    /** Creates new form InterfaceA */
    public InterfaceA() {
        initComponents();
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jButton1 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();
        jButton4 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jButton1.setText("Iniciar Servidor");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jButton2.setText("Iniciar Cliente");
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });

        jButton4.setText("Enviar Mensagem");
        jButton4.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton4ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jButton1)
                    .addComponent(jButton4))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jButton2)
                .addContainerGap(170, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(24, 24, 24)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton1)
                    .addComponent(jButton2))
                .addGap(18, 18, 18)
                .addComponent(jButton4)
                .addContainerGap(212, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        try {
            Receiver.IniciarServidor();
        } catch (IOException ex) {
            Logger.getLogger(InterfaceA.class.getName()).log(Level.SEVERE, null, ex);
        }
}                                        

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
Transport.IniciarCliente();       
}                                        

    private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        try {
            Transport.EnviarMsg();
        } catch (IOException ex) {
           JOptionPane.showMessageDialog(null, ex.getMessage());
        }
    }                                        

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(InterfaceA.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(InterfaceA.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(InterfaceA.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(InterfaceA.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new InterfaceA().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JButton jButton4;
    // End of variables declaration
}
#3