Java - 具有多个客户端错误的服务器

Question

我不熟悉使用 Java 创建服务器和多个客户端的概念，如果这是一个明显的解决方法，我深表歉意。我一直在尝试编写一个 jframe 聊天程序，它有一个服务器和两个客户端，它们目前都使用相同的端口。客户端发送的任何数据都将传递给服务器，服务器将显示它。到目前为止，代码是这样做的，但是，我还想将所述数据传递给另一个客户端。我正在尝试对程序进行编码，以便我可以指定数据发送到的客户端。

代码如下：

服务器代码。

package Chats;

import java.io.*;
import java.net.*;

public class Chat_Server extends javax.swing.JFrame 
{
    static ServerSocket ss;
    static Socket s;
    static DataInputStream din;
    static DataOutputStream dout;

    public Chat_Server() 
    {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jScrollPane1 = new javax.swing.JScrollPane();
        Msg_Area = new javax.swing.JTextArea();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        Msg_Area.setColumns(20);
        Msg_Area.setRows(5);
        jScrollPane1.setViewportView(Msg_Area);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(32, 32, 32)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 332, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(36, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(24, 24, 24)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 237, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(39, Short.MAX_VALUE))
        );

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

    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(Chat_Server.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Chat_Server.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Chat_Server.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Chat_Server.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        java.awt.EventQueue.invokeLater(new Runnable() 
        {
            public void run() 
            {
                new Chat_Server().setVisible(true);
            }
        });

        String msgin = "";
        try
        {
            ss = new ServerSocket(1201); // Server starts at 1201 port number
            s = ss.accept(); // Now server will accept the connections.
            din = new DataInputStream(s.getInputStream());
            dout = new DataOutputStream(s.getOutputStream());

            while(!msgin.equals("exit"))
            {
                msgin = din.readUTF();
                Msg_Area.setText(Msg_Area.getText().trim() + "\n Client: \t" + msgin); // Displaying the message from client  
            }
        }

        catch(Exception e)
        {

        }
    }

    // Variables declaration - do not modify                     
    private static javax.swing.JTextArea Msg_Area;
    private javax.swing.JScrollPane jScrollPane1;
    // End of variables declaration                   
}

客户端代码。

package Chats;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.net.Socket;

public class Chat_Client extends javax.swing.JFrame
{
    static Socket s;
    static DataInputStream din;
    static DataOutputStream dout;

    public Chat_Client() 
    {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        Msg_Text = new javax.swing.JTextField();
        jScrollPane1 = new javax.swing.JScrollPane();
        Msg_Area = new javax.swing.JTextArea();
        Msg_Send = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        Msg_Text.setText("jTextField1");

        Msg_Area.setColumns(20);
        Msg_Area.setRows(5);
        jScrollPane1.setViewportView(Msg_Area);

        Msg_Send.setText("jButton1");
        Msg_Send.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                Msg_SendActionPerformed(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()
                .addGap(29, 29, 29)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 332, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(Msg_Text, javax.swing.GroupLayout.PREFERRED_SIZE, 257, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 31, Short.MAX_VALUE)
                        .addComponent(Msg_Send)))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGap(19, 19, 19)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 196, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 31, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(Msg_Text, javax.swing.GroupLayout.PREFERRED_SIZE, 31, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(Msg_Send))
                .addGap(23, 23, 23))
        );

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

    private void Msg_SendActionPerformed(java.awt.event.ActionEvent evt) {                                         
        try
        {
            String msgout = "";
            msgout = Msg_Text.getText().trim();
            dout.writeUTF(msgout);
        }

        catch (Exception e)
        {
            //handle exceptions here.
        }
    }                                        

    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(Chat_Client.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Chat_Client.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Chat_Client.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Chat_Client.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        java.awt.EventQueue.invokeLater(new Runnable() 
        {
            public void run() 
            {
                new Chat_Client().setVisible(true);
            }
        });

        try
        {
            s = new Socket ("127.0.0.1", 1201); // Here the ip ddress is local address.
            din = new DataInputStream(s.getInputStream());
            dout = new DataOutputStream(s.getOutputStream());
            String msgin = "";

            while (!msgin.equals("exit"))
            {
                msgin = din.readUTF();
                Msg_Area.setText(Msg_Area.getText().trim() + "\n Server: \t" + msgin);
            }

        }

        catch(Exception e)
        {
            //Exception Code
        }    
    }

    // Variables declaration - do not modify                     
    private static javax.swing.JTextArea Msg_Area;
    private javax.swing.JButton Msg_Send;
    private javax.swing.JTextField Msg_Text;
    private javax.swing.JScrollPane jScrollPane1;
    // End of variables declaration                   

}

我为另一个客户设置了另一个页面，但到目前为止，代码是第一个客户页面的副本，所以发布它没有意义。

Answer 1

您只接受一个带有ss.accept() 的客户，仅此而已。 ServerSocket#accept 等待一个传入的客户端连接并创建一个 Socket 对象。为了接受多个连接，您需要不断循环 ss.accept() 以继续侦听其他客户端连接。建立新连接后，您可以将其添加到列表中。 （我没有测试过代码，更多的只是给你指出你需要的方向）

public static void main(String []args) throw Exception{
    ServerSocket serverSocket = new ServerSocket(1201);
    List<Socket> clients = new ArrayList<Socket>();

    while(true) {//continuously listening for a new connection
        Socket client = serverSocket.accept(); 
        clients.add(client); 
    }
} 

现在的问题是，如果您的服务器不断侦听连接，它将阻塞您的线程。因此，每次添加连接时，都会产生一个新线程来处理它。

public static void main(String []args) throw Exception{
    ServerSocket serverSocket = new ServerSocket(1201);
    List<Socket> clients = new ArrayList<Socket>();

    while(true) {
        Socket client = serverSocket.accept();
        clients.add(client);
        new Thread(new Runnable(){
           public void run(){
              //Handle socket here
           }
        }).start();
    }
}

如果你想避免像这样创建多个线程，那么你将不得不使用 nio socketchannels。