如何让2台计算机在Java中相互通信以便即时通讯？

Question

我一直在使用Java代码的即时通讯工具一段时间了。只有当我在同一台计算机上运行服务器和客户端，然后他们进行通信时，我才能使其工作。但我不能让2台不同的电脑连接到同一台服务器，并沟通。我看了很多例子，但我还是不明白需要改变什么。我将在下面显示的代码大部分都可以忽略，只有网络部分需要查看。服务器连接位于客户端代码的底部。我是初学者，我很感激任何帮助。谢谢。

客户端代码：

import javax.swing.*; 
import javax.swing.text.DefaultCaret; 

import java.awt.*; 
import java.awt.event.*; 
import java.text.*; 
import java.util.Date; 
import java.net.*; 
import java.io.*; 



public class NukeChatv3 extends JFrame 
{ 

private JTextArea showtext; 
private JTextField usertext; 
private String hostname; 
private Socket connectionsock; 
private BufferedReader serverinput; 
private PrintWriter serveroutput; 
private int port; 


private static final long serialVersionUID = 1L; 

private class entersend implements KeyListener 
{ 
     public void keyTyped (KeyEvent e) 
     { 

     } 
     public void keyPressed (KeyEvent e) 
     { 
      String text = usertext.getText(); 

      if(e.getKeyCode()== KeyEvent.VK_ENTER) 
      { 
       if (usertext.getText().equals("")) 
        return; 
       else 
       { 
        //try{ 
        serveroutput.println(text); 

        usertext.setText(""); 
        //showtext.append("[" + ft.format(dNow) + "]" + "\n" + "UserName: " + serverdata +"\n\n"); 
        //} 
        /*catch(IOException in) 
        { 
         showtext.append(in.getMessage()); 
        }*/ 

       } 
      } 
      else 
       return; 
     } 
     public void keyReleased (KeyEvent e) 
     { 

     } 
} 

private class sender implements ActionListener 
{ 
    public void actionPerformed(ActionEvent e) 
    { 
     if (usertext.getText().equals("")) 
      return; 
     else 
     { 
      Date dNow = new Date(); 
      SimpleDateFormat ft = new SimpleDateFormat ("hh:mm:ss"); 
      String text = usertext.getText(); 
      usertext.setText(""); 

      //* Send message to server 



      showtext.append(ft.format(dNow) + "\n" + "UserName: " + text +"\n\n"); 
     } 
    } 
} 

private class startconnection implements ActionListener 
{ 
    public void actionPerformed(ActionEvent e) 
    { 
     clientconnection connect = new clientconnection(); 
     connect.start(); 
    } 
} 

private class CheckOnExit implements WindowListener 
{ 
    public void windowOpened(WindowEvent e) 
    {} 

    public void windowClosing(WindowEvent e) 
    { 
     ConfirmWindow checkers = new ConfirmWindow(); 
     checkers.setVisible(true); 
    } 

    public void windowClosed(WindowEvent e) 
    {} 

    public void windowIconified(WindowEvent e) 
    {} 

    public void windowDeiconified(WindowEvent e) 
    {} 

    public void windowActivated(WindowEvent e) 
    {} 

    public void windowDeactivated(WindowEvent e) 
    {} 
} 


private class ConfirmWindow extends JFrame implements ActionListener 
{ 

    private static final long serialVersionUID = 1L; 

    public ConfirmWindow() 
    { 
     setSize(200, 100); 
     getContentPane().setBackground(Color.LIGHT_GRAY); 
     setLayout(new BorderLayout()); 

     JLabel confirmLabel = new JLabel(
         "Are you sure you want to exit?"); 
     add(confirmLabel, BorderLayout.CENTER); 

     JPanel buttonPanel = new JPanel(); 
     buttonPanel.setBackground(Color.GRAY); 
     buttonPanel.setLayout(new FlowLayout()); 

     JButton exitButton = new JButton("Yes"); 
     exitButton.addActionListener(this); 
     buttonPanel.add(exitButton); 

     JButton cancelButton = new JButton("No"); 
     cancelButton.addActionListener(this); 
     buttonPanel.add(cancelButton); 

     add(buttonPanel, BorderLayout.SOUTH); 
    } 

    public void actionPerformed(ActionEvent e) 
    { 
     String actionCommand = e.getActionCommand(); 

     if (actionCommand.equals("Yes")) 
      System.exit(0); 
     else if (actionCommand.equals("No")) 
      dispose(); 
     else 
      System.out.println("Unexpected Error in Confirm Window."); 
    } 
} 


public static void main(String[] args) 
{ 

    NukeChatv3 nuke = new NukeChatv3(); 
    nuke.setVisible(true); 

} 

public NukeChatv3() 
{  
     setTitle("NukeChat v3"); 
     setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE); 
     setSize(550, 400); 
     setResizable(false); 
     addWindowListener(new CheckOnExit()); 
     addWindowListener(new WindowAdapter(){ 
      public void windowOpened(WindowEvent e){ 
       usertext.requestFocus(); 
      } 
     }); 
     getContentPane().setBackground(Color.BLACK); 
     setLayout(new GridBagLayout()); 
     GridBagConstraints c = new GridBagConstraints(); 

     showtext = new JTextArea(15, 35); 
     showtext.setEditable(false); 
     showtext.setLineWrap(true); 
     DefaultCaret caret = (DefaultCaret)showtext.getCaret(); 
     caret.setUpdatePolicy(DefaultCaret.ALWAYS_UPDATE); 


     JScrollPane scrollbar = new JScrollPane(showtext); 
     scrollbar.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER); 
     scrollbar.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); 
     c.anchor = GridBagConstraints.FIRST_LINE_START; 
     //c.gridwidth = 2; 
     c.insets = new Insets(20, 20, 20, 20); 
     c.weightx = .5; 
     c.weighty = .5; 
     c.gridx = 0; 
     c.gridy = 0; 
     add(scrollbar, c); 

     usertext = new JTextField(35); 

     usertext.requestFocusInWindow(); 
     usertext.addKeyListener(new entersend()); 
     //c.gridwidth = 1; 
     c.insets = new Insets(0, 20, 0, 0); 
     c.weightx = .5; 
     c.gridx = 0; 
     c.gridy = 1; 
     add(usertext, c); 

     JPanel empty = new JPanel(); 
     c.gridx = 1; 
     c.gridy = 0; 
     empty.setLayout(new GridLayout(2,1)); 

     JButton test1 = new JButton("test1"); 
     empty.add(test1); 

     JButton test2 = new JButton("test2"); 
     empty.add(test2); 

     add(empty, c); 

     JButton send = new JButton("Send"); 
     send.addActionListener(new sender()); 
     c.ipady = -5; 
     c.insets = new Insets(0, 0, 20, 0); 
     c.gridx = 1; 
     c.gridy = 1; 
     add(send, c); 

     JMenu menu = new JMenu("File"); 
     JMenuItem connection = new JMenuItem("Connect"); 
     connection.addActionListener(new startconnection()); 
     menu.add(connection); 

     JMenuBar bar = new JMenuBar(); 
     bar.add(menu); 
     setJMenuBar(bar); 



} 

private class clientconnection extends Thread 
{ 
    public void run() 
    { 
     try 
     { 
      // Set host name and port// 
      hostname = "localhost"; 
      port = 16666; 

      // connect to socket of the server// 
      connectionsock = new Socket(hostname, port); 

      // set up client input from server// 
      serverinput = new BufferedReader(new InputStreamReader(connectionsock.getInputStream())); 

      // set up client output to server// 
      serveroutput = new PrintWriter(connectionsock.getOutputStream(), true); 

      // set up a looping thread to constantly check if server has sent anything 
      String serverdata = ""; 

      while ((serverdata = serverinput.readLine()) != null) 
      { 
       Thread.sleep(500); 
       Date dNow = new Date(); 
       SimpleDateFormat ft = new SimpleDateFormat ("hh:mm:ss"); 
       showtext.append("[" + ft.format(dNow) + "]" + "\n" +"Recieved from server: \n" + "UserName: " + serverdata +"\n\n"); 
      } 

     } 

     catch(IOException e) 
     { 
      System.out.println(e.getMessage()); 
     } 
     catch(InterruptedException inter) 
     { 
      showtext.append("Unexpected interruption\n\n"); 
     } 
    } 


} 

}

服务器代码：

import java.net.ServerSocket; 
import java.io.*; 
import java.net.Socket; 
import java.io.DataOutputStream; 
import java.io.BufferedReader; 
import java.io.InputStreamReader; 
import java.io.IOException; 
import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 



public class servertest extends JFrame 
{ 

private JButton start; 
private JTextArea text; 
private BufferedReader clientinput; 
private PrintWriter clientoutput; 

private class listen implements ActionListener 
{ 
    public void actionPerformed(ActionEvent e) 
    { 
     connection connect = new connection(); 
     connect.start(); 
    } 
} 

public servertest() 
{ 
    setSize(400,300); 
    setLayout(new BorderLayout()); 
    start = new JButton("Start"); 
    start.addActionListener(new listen()); 
    add(start, BorderLayout.SOUTH); 

    text = new JTextArea(6, 10); 
    text.setEditable(false); 
    add(text, BorderLayout.CENTER); 
} 
private class connection extends Thread 
{ 
    public void run() 
    { 
    try 
    { 
     // Sets up a server socket with set port// 
     text.setText("Waiting for connection on port 16666"); 
     ServerSocket serversock = new ServerSocket(16666); 

     // Waits for the Client to connect to the server// 
     Socket connectionsock = serversock.accept(); 

     // Sets up Input from the Client to go to the server// 
     clientinput = new BufferedReader(new InputStreamReader(connectionsock.getInputStream())); 

     // Sets up data output to send data from server to client// 
     clientoutput = new PrintWriter(connectionsock.getOutputStream(), true); 

     // Test server to see if it can perform a simple task// 
     text.setText("Connection made, waiting to client to send there name"); 
     clientoutput.println("Enter your name please."); 

     // Get users name// 
     String clienttext = clientinput.readLine(); 

     // Reply back to the client// 
     String replytext = "Welcome " + clienttext; 
     clientoutput.println(replytext); 
     text.setText("Sent: " + replytext); 

     while ((replytext = clientinput.readLine()) != null) 
     { 
      clientoutput.println(replytext); 
      text.setText("Sent: " + replytext); 
     } 

     // If you need to close the Socket connections 
     // clientoutput.close(); 
     // clientinput.close(); 
     // connetionsock.close(); 
     // serversock.close(); 

    } 

    catch(IOException e) 
    { 
     System.out.println(e.getMessage()); 
    } 
    } 
} 

public static void main(String[] args) 
{ 
    servertest test = new servertest(); 
    test.setVisible(true); 
} 

Answer 1

在您的客户端代码，在服务器运行的是指定正确的主机名/ IP地址：

private class clientconnection extends Thread 
{ 
    public void run() 
    { 
     try 
     { 
      // Set host name and port// 
      hostname = "localhost"; //<---- Change this to server IP address 
      port = 16666;