Java多客户端聊天应用程序 - 发送消息问题

Question

我的问题是，我仍然可以在客户端（客户端到客户端）之间发送消息，但发送两次或三次后，消息不再显示给接收者。

所以基本上每当客户希望发送消息到另一个客户时，消息首先被发送到服务器。但正如你从我的编码中已经注意到的那样，我正在以对象的形式发送服务器数据。 例如：

send(new ChatMessage(type, sender, content, recipient)); 

当你发送消息的类型是“信息”。当服务器收到对象时，它会检查接收数据及其类型。 例如：

ChatMessage cm = (ChatMessage) in[client[id].readObject(); 
if(cm.type.equals("message"){ 
    send(findUserThread(toWhom), new ChatMessage("message", sender, content, recipient); 

} 

如果类型是“信息”，然后将其发送该特定客户端的消息。

我在客户端使用System.out.println（）来查看来自服务器的传入数据。所以当我尝试发送一些消息时，它工作正常，但在发送一些消息后，我的聊天屏幕上没有显示任何消息。

根据我的逻辑错误可以是：

1中的JList

所选索引

2客户端[]数组或用户名[]数组

3的ObjectOutputStream和ObjectInputStream的

ServerGUI类（服务器端）

package test2; 

import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 
import java.io.*; 
import java.net.*; 
import java.text.SimpleDateFormat; 
import java.util.Date; 
import java.util.*; 
import java.util.zip.GZIPOutputStream; 
import javax.swing.SwingUtilities; 

public class ServerGUI extends JFrame implements ActionListener { 

public JList online; 
private JTextField ipaddress, textMessage; 
private JButton send, start, disconnect; 
private JTextArea chatArea; 
private JLabel port; 
int client[] = new int[100]; 
private ObjectOutputStream out[] = new ObjectOutputStream[client.length + 1]; 
private ObjectInputStream in[] = new ObjectInputStream[client.length + 1]; 
String username[] = new String[client.length + 1]; 
static String b; 
public String nm, usm; 
private ServerSocket server; 
private Socket connect; 
boolean success = true; 
int id = 0; 
ArrayList<String> UserList = new ArrayList<String>(); 


public ServerGUI() { 
    Container c = getContentPane(); 
    c.setLayout(new BorderLayout()); 
    c.setPreferredSize(new Dimension(650, 500)); 


    JPanel p = new JPanel(); 
    p.setLayout(new FlowLayout()); 
    p.setBackground(Color.LIGHT_GRAY); 
    p.add(port = new JLabel("Port No")); 
    p.add(ipaddress = new JTextField("1500")); 
    p.add(start = new JButton("START")); 
    p.add(disconnect = new JButton("DISCONNECT")); 
    disconnect.setEnabled(false); 
    start.setBorderPainted(false); 
    start.setBackground(Color.blue); 
    start.setForeground(Color.WHITE); 
    disconnect.setBorderPainted(false); 
    disconnect.setBackground(Color.blue); 
    disconnect.setForeground(Color.WHITE); 
    ipaddress.setCaretPosition(0); 

    JPanel p1 = new JPanel(); 
    p1.setLayout(new FlowLayout()); 
    p1.setBackground(Color.LIGHT_GRAY); 
    p1.add(chatArea = new JTextArea()); 

    chatArea.setPreferredSize(new Dimension(300, 350)); 
    chatArea.setLineWrap(true); 
    chatArea.setEditable(false); 

    JPanel p2 = new JPanel(); 
    p2.setLayout(new FlowLayout()); 
    p2.setBackground(Color.LIGHT_GRAY); 
    p2.add(textMessage = new JTextField(20)); 

    p2.add(send = new JButton("SEND")); 
    send.setBackground(Color.blue); 
    send.setForeground(Color.WHITE); 
    send.setBorderPainted(false); 

    start.addActionListener(this); 
    send.addActionListener(this); 


    c.add(p, BorderLayout.NORTH); 
    c.add(p1, BorderLayout.CENTER); 
    c.add(p2, BorderLayout.SOUTH); 


} 
//current time 
SimpleDateFormat log = new SimpleDateFormat("HH:mm"); 
String d = log.format(new Date()); 

//Start server 
public void Start() { 

    int portNo = 0; 
    try { 

     String no = ipaddress.getText(); 
     portNo = Integer.parseInt(no); 
     chatArea.append("Connection to port " + portNo + "...\n"); 
     server = new ServerSocket(portNo); 
     success = true; 

    } catch (Exception ex) { 
     chatArea.append("Error cannot bind to port \n"); 
     success = false; 
    } 

    if (success == true) { 
     addClient ob1 = new addClient("RunServer"); 
     start.setEnabled(false); 
     disconnect.setEnabled(true); 
    } 
} 

public class addClient implements Runnable { 

    Thread t; 

    addClient(String tot) { 
     t = new Thread(this, tot); 
     t.start(); 
    } 

    public void run() { 
     while (true) { 
      try { 
       try { 
        WaitClient(); 
       } catch (Exception ex) { 
        break; 
       } 

       for (int i = 0; i < client.length; i++) { 
        if (client[i] == 0) { 
         client[i] = i + 1; 
         id = i; 
         break; 
        } 
       } 

       //set stream to send and receive data 
       out[client[id]] = new ObjectOutputStream(connect.getOutputStream()); 
       out[client[id]].flush(); 
       in[client[id]] = new ObjectInputStream(connect.getInputStream()); 
       chatArea.append(d + " Client:[" + client[id] + "] : Connected successful \n"); 
       chatArea.setCaretPosition(chatArea.getText().length()); 
       //inform user that connection is successfull      
       ChatMessage cm = (ChatMessage) in[client[id]].readObject(); // read client username 
       if(cm.type.equals("login")){ 
        chatArea.append("User " +cm.sender + " connected successfully" + "\n"); 
        username[client[id]] = cm.sender; 
        System.out.println(username[0]+ username[1]+ username[2]); 
        send(client[id], new ChatMessage("login", username[client[id]], "user", "SERVER")); 
        sendUserList(cm.sender); 
        Announce("newuser", "SERVER", cm.sender); 




       } 




       Chat c = new Chat(client[id], "StartChat" + client[id]); // make new thread for every new client 

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


    } 

} 

public class Chat implements Runnable { 

    int id1; 
    Chat ob1; 
    Thread t; 

    Chat(int id1, String info1) { 
     this.id1 = id1; // create a thread for client 
     t = new Thread(this, info1); 
     t.start(); 
    } 

    public void run() { 
    boolean running = true; 
     while(running){ 
      try { 
       ChatMessage cm = (ChatMessage) in[client[id]].readObject(); // read client username 
       if(cm.type.equals("message")){ 

         send(findUserThread(cm.recipient), new ChatMessage(cm.type, cm.sender, cm.content, cm.recipient)); 


       } 

      } catch (Exception e) { 

      } 
     } 

    } 
} 




//wait for connection, then display connection information 
private void WaitClient() throws IOException { 

    chatArea.append(d + " : Waiting for connection... \n"); 
    connect = server.accept(); 

    chatArea.append(d + " : Now connected to " + connect.getInetAddress().getHostName() + "\n"); 
} 

//send message to specific user 
public void sendUser(int number, String info) { 

    try { 
     out[number].writeObject(info); 
     out[number].flush(); 
    } catch (Exception e) { 
    } 

} 

public void sendServer(String por) { 
    for (int i = 0; i < client.length; i++) // for loop trying to send message from server to all clients 
    { 
     if (client[i] != 0) // this line stop server to send messages to offline clients 
     { 
      try { 
       out[i + 1].writeObject(por); 
       out[i + 1].flush(); 
      } catch (Exception e) { 
      } 
     } 
    } 
} 

public void Announce(String type, String sender, String content){ 

    ChatMessage cm = new ChatMessage(type, sender, content, "All"); 
    for(int i = 0; i < id; i++){ 
     send(client[i], cm); 
    } 
} 



public void send(int number, ChatMessage cm) { 

    try { 
     out[number].writeObject(cm); 
     out[number].flush(); 
    } catch (Exception e) { 
    } 

} 





void sendAll(int num, String por) { 
    for (int i = 0; i < client.length; i++) // for loop trying to send message from server to all clients 
    { 
     if (client[i] != 0) // this line stop server to send messages to offline clients (if "clientNiz[X] = 0" don't try to send him message, because that slot is empty) 
     { 
      if (num != i + 1) // don't repeat messages (when for ex. client_1 send message to all clients, this line stop server to send same message back to client_1) 
      { 
       try { 
        out[i + 1].writeObject(por); 
        out[i + 1].flush(); 
       } catch (Exception e) { 
       } 
      } 
     } 
    } 
} 

public void sendUserList(String toWhom){ 
    for(int i = 0; i <= id; i++){ 
     send(findUserThread(toWhom), new ChatMessage("newuser", "SERVER", username[client[i]], toWhom)); 
    } 
} 

public int findUserThread(String usr){ 
    for(int i = 0; i <= id; i++){ 
     if(username[client[i]].equals(usr)){ 
      return client[i]; 
     } 

    } 
    return -1; 
} 

    private int findClient(int num){ 
    for (int i = 0; i <= id; i++){ 
     if (client[i] == (num+1)){ 
       return i; 
      } 
} 
return -1; 
} 





public void actionPerformed(ActionEvent e) { 
    if (e.getSource() == send) { 
     //current time 

     String s1 = textMessage.getText(); 
     send(client[id], new ChatMessage("message", "admin", s1, "client")); 
     chatArea.append("Administrator: " + s1 + "\n"); 


    } else if (e.getSource() == start) { 
     Start(); 
    } 
    if (e.getSource() == disconnect) { 

     try { 
      server.close(); 
     } catch (Exception ex) { 
     } 

     for (int i = 0; i < client.length; i++) { 
      try { 
       in[i].close(); 
       out[i].close(); 
      } catch (Exception ex) { 
      } 
     } 
     chatArea.append("Server is disconnected\n"); 
     start.setEnabled(true); 
     disconnect.setEnabled(false); 
    } 
} 
} 

MainGUI类（客户端）

package test2; 

import java.io.*; 
import java.net.*; 
import java.text.SimpleDateFormat; 
import java.util.ArrayList; 
import java.util.Date; 
import java.io.BufferedOutputStream; 
import java.io.DataOutputStream; 
import java.io.File; 
import java.io.FileOutputStream; 
import javax.swing.DefaultListModel; 
import javax.swing.JFileChooser; 


public class MainGUI extends javax.swing.JFrame { 

public MainGUI() { 
    initComponents(); 





} 

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

    jButton1 = new javax.swing.JButton(); 
    jButton3 = new javax.swing.JButton(); 
    start = new javax.swing.JButton(); 
    jLabel2 = new javax.swing.JLabel(); 
    textMessage = new javax.swing.JTextField(); 
    jScrollPane2 = new javax.swing.JScrollPane(); 
    chatArea = new javax.swing.JTextArea(); 
    usernm = new javax.swing.JTextField(); 
    jLabel1 = new javax.swing.JLabel(); 
    send = new javax.swing.JButton(); 
    upload = new javax.swing.JButton(); 
    filename = new javax.swing.JTextField(); 
    jScrollPane1 = new javax.swing.JScrollPane(); 
    online = new javax.swing.JList(); 

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 
    setTitle("ICARE "); 
    setFocusable(false); 
    setPreferredSize(new java.awt.Dimension(840, 650)); 
    setResizable(false); 
    getContentPane().setLayout(null); 

    jButton1.setText("Video Call"); 
    getContentPane().add(jButton1); 
    jButton1.setBounds(270, 10, 100, 30); 

    jButton3.setText("Send"); 
    jButton3.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      jButton3ActionPerformed(evt); 
     } 
    }); 
    getContentPane().add(jButton3); 
    jButton3.setBounds(690, 100, 100, 30); 

    start.setBackground(new java.awt.Color(51, 51, 255)); 
    start.setFont(new java.awt.Font("Tahoma", 0, 14)); // NOI18N 
    start.setForeground(new java.awt.Color(255, 255, 255)); 
    start.setText("Start"); 
    start.setBorder(null); 
    start.setBorderPainted(false); 
    start.setRequestFocusEnabled(false); 
    start.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      startActionPerformed(evt); 
     } 
    }); 
    getContentPane().add(start); 
    start.setBounds(630, 50, 90, 40); 
    getContentPane().add(jLabel2); 
    jLabel2.setBounds(0, 0, 820, 0); 
    getContentPane().add(textMessage); 
    textMessage.setBounds(270, 450, 420, 70); 

    chatArea.setColumns(20); 
    chatArea.setFont(new java.awt.Font("Arial", 0, 14)); // NOI18N 
    chatArea.setRows(5); 
    jScrollPane2.setViewportView(chatArea); 

    getContentPane().add(jScrollPane2); 
    jScrollPane2.setBounds(270, 140, 520, 300); 
    getContentPane().add(usernm); 
    usernm.setBounds(450, 60, 170, 30); 

    jLabel1.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N 
    jLabel1.setText("Enter your nickname:"); 
    getContentPane().add(jLabel1); 
    jLabel1.setBounds(270, 60, 150, 30); 

    send.setBackground(new java.awt.Color(51, 51, 255)); 
    send.setFont(new java.awt.Font("Tahoma", 0, 14)); // NOI18N 
    send.setForeground(new java.awt.Color(255, 255, 255)); 
    send.setText("Send"); 
    send.setBorder(null); 
    send.setBorderPainted(false); 
    send.setRequestFocusEnabled(false); 
    send.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      sendActionPerformed(evt); 
     } 
    }); 
    getContentPane().add(send); 
    send.setBounds(700, 470, 90, 40); 

    upload.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N 
    upload.setText("+"); 
    upload.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      uploadActionPerformed(evt); 
     } 
    }); 
    getContentPane().add(upload); 
    upload.setBounds(633, 100, 50, 30); 
    getContentPane().add(filename); 
    filename.setBounds(270, 100, 350, 30); 

    jScrollPane1.setViewportView(online); 

    getContentPane().add(jScrollPane1); 
    jScrollPane1.setBounds(30, 20, 220, 500); 

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

private void startActionPerformed(java.awt.event.ActionEvent evt) {          
    Start(); 


}          

private void sendActionPerformed(java.awt.event.ActionEvent evt) {          
    // TODO add your handling code here: 
    String z = textMessage.getText(); 
    String target = online.getSelectedValue().toString(); 
    chatArea.append("[ " + usernm.getText() + " ] : " + z + "\n"); 

    send(new ChatMessage("message", usernm.getText(), z, target)); 
    textMessage.setText("");   


}          

private void uploadActionPerformed(java.awt.event.ActionEvent evt) {          
    // TODO add your handling code here: 
    //Create a file chooser 
//In response to a button click: 
JFileChooser fileChooser = new JFileChooser(); 
    fileChooser.showDialog(this, "Select File"); 
    file = fileChooser.getSelectedFile(); 

    if(file != null){ 
     if(!file.getName().isEmpty()){ 
      String str; 

      if(filename.getText().length() > 30){ 
       String t = file.getPath(); 
       str = t.substring(0, 20) + " [...] " + t.substring(t.length() - 20, t.length()); 
      } 
      else{ 
       str = file.getPath(); 
      } 
      filename.setText(str); 
     } 
    } 
}          

private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {           
    // TODO add your handling code here: 
     long size = file.length(); 
     if(size < 120 * 1024 * 1024){ 
      sendUser("download"); 


     } 
     else{ 
      chatArea.append("File is size too large\n"); 
     } 
}           

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(MainGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
    } catch (InstantiationException ex) { 
     java.util.logging.Logger.getLogger(MainGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
    } catch (IllegalAccessException ex) { 
     java.util.logging.Logger.getLogger(MainGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
    } catch (javax.swing.UnsupportedLookAndFeelException ex) { 
     java.util.logging.Logger.getLogger(MainGUI.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 MainGUI().setVisible(true); 

     } 
    }); 
} 
// Variables declaration - do not modify 
public javax.swing.JTextArea chatArea; 
private javax.swing.JTextField filename; 
private javax.swing.JButton jButton1; 
private javax.swing.JButton jButton3; 
private javax.swing.JLabel jLabel1; 
private javax.swing.JLabel jLabel2; 
private javax.swing.JScrollPane jScrollPane1; 
private javax.swing.JScrollPane jScrollPane2; 
public javax.swing.JList online; 
private javax.swing.JButton send; 
private javax.swing.JButton start; 
private javax.swing.JTextField textMessage; 
private javax.swing.JButton upload; 
private javax.swing.JTextField usernm; 
// End of variables declaration 


private ObjectOutputStream out; 
private ObjectInputStream in; 
static String b; //variable for message 
private Socket join; 
boolean success = true; 
private String serverIP = "127.0.0.1"; //set IP Address 
ArrayList<String> userlist = new ArrayList<String>(); //ArrayList to store online users 
//current time 
SimpleDateFormat log = new SimpleDateFormat("HH:mm"); 
String d = log.format(new Date()); 
public File file; 
public DefaultListModel model = new DefaultListModel(); 



//Start client program 
public void Start() { 

    try { 

     start.setEnabled(false); 
     chatArea.append(d + " : Attempting connection... \n"); 

     join = new Socket(serverIP, 10500); 
     chatArea.append(d + " : Connected to - " + join.getInetAddress().getHostName() + "\n"); 

     success = true; 

    } catch (Exception ex) { 
     chatArea.append("Error cannot bind to port \n");    
     success = false; 
    } 

    if (success == true) { 

     ClientThread ct = new ClientThread(); 


    } 
} 

class ClientThread implements Runnable { 

    ClientThread ct; 
    Thread t; 

    ClientThread() { 
     t = new Thread(this, "RunClient"); 
     t.start(); 

    } 

    public void run() { 
     try { 
      try { 
       out = new ObjectOutputStream(join.getOutputStream()); 
       out.flush(); 
       in = new ObjectInputStream(join.getInputStream()); 

       send(new ChatMessage("login", usernm.getText(), "password", "SERVER"));     
      } catch (Exception e) { } 



      CThread c1 = new CThread(); 


     } catch (Exception ex) { } 
    } 
} 

class CThread implements Runnable { 

    CThread ob1; 
    Thread t; 

    CThread() { 
     t = new Thread(this, "Message"); 
     t.start(); 
    } 


    public void run() { 
     boolean running = true; 
     try { 
      while(running){ 
       try { 

        ChatMessage cm = (ChatMessage) in.readObject(); 
        System.out.println("Incoming :" + cm.toString()); 
        if(cm.type.equals("login")){ 
        chatArea.append(cm.sender + " is online" + "\n"); 
        }else if(cm.type.equals("message")){       
         if(cm.recipient.equals(usernm.getText())){ 
           chatArea.append("[ "+cm.sender +" ] : " + cm.content + "\n"); 

         } 
        }else if(cm.type.equals("newuser")){ 

         online.setModel(model); 
         model.addElement(cm.content); 
        } 

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





void sendUser(String por) { 
    try { 
     out.writeObject(por); 
     out.flush(); 
    } catch (Exception e) { 
    } 
} 

void send(ChatMessage cm){ 
    try { 
     out.writeObject(cm); 
     out.flush(); 
    } catch (Exception e) { 
    } 

} 


} 

ChatMessage类

package test2; 

import java.io.Serializable; 

public class ChatMessage implements Serializable{ 

private static final long serialVersionUID = 1L; 
public String type, sender, content, recipient; 

public ChatMessage(String type, String sender, String content, String recipient){ 
    this.type = type; this.sender = sender; this.content = content; this.recipient = recipient; 
} 

@Override 
public String toString(){ 
    return "{type='"+type+"', sender='"+sender+"', content='"+content+"', recipient='"+recipient+"'}"; 
} 
} 

ServerTest运行ServerGUI

公共类ServerTest { 公共静态无效主要（字符串ARGS []）{

ServerGUI m = new ServerGUI(); 

    m.setTitle("Server"); 

    m.setVisible(true); 

    m.pack(); 

    //to make to the center of the screen 

    m.setLocationRelativeTo(null); 


} 
} 

Answer 1

• Java中的类应以大写字母开头。例如：ServerGUI但不是addClient在您的代码中可见。
• 类表示对象。或对象的“类”。例如Car或ServerGUI而不是addClient。什么是new addClient()？这真的是一个对象吗？
• 如果可能的话，变量名应该有重要的名称。例如Car limousine = new Car(4,Color.Black)而不是addClient ob1 = new addClient("RunServer")。 ob1是什么意思？
• 评论对读者来说是新鲜的空气。请使用评论。例如：//we are going to represent the server as a special user with admin privileges
• 方法名称ir Java不应以大写字母开头。这是一个不好的例子：private void WaitClient() throws IOException
• 缩进和空行。不知道它是部分还是完全是你的错，但代码坏缩进，块内空行（不只是一个或两个，也不作为分隔符），并错过空格（if(cm.type.equals("login")){）
• StackOverflow不是您的问题的好地方。人们在这里提出具体问题。你的问题并不是一个具体的问题，它更像是一个“我的程序不工作”的问题。

结论：你的代码是难以阅读和理解。看起来你是Java的新手，所以请先从简单而简单的例子开始，使用诸如Eclipse或Netbeans之类的Java IDE并花费你的时间！你不会在一周内学习Java，要有耐心。

对不起，如果我太老实，但这就是我的想法（也许这里没有人会帮助你的原因之一）。

Answer 2

但发送两个或三个消息后，我的程序停止发送邮件

你应该尝试调试应用程序的第一次。使用日志或System.out.println，您可以轻松找出“停止”的位置。消息是否被发送到服务器？服务器是否将消息发送给客户端？你可以用几个println回答这些问题。

一旦你知道了哪里（在你的代码中，哪个方法），它是失败的，你可以发布一个更具体的问题，如果你仍然需要帮助。

另外，当您遇到问题时，请详细说明问题是什么。应用程序崩溃了吗？它会停止向每个人发送消息吗？ “我的程序停止发送消息”有点含糊。

编辑：好了，现在我看到的代码，请不要这样做：

void send(ChatMessage cm){ 
    try { 
     out.writeObject(cm); 
     out.flush(); 
    } catch (Exception e) { 
    } 
} 

如果抛出一个异常，你不会注意到。
您应该添加：

e.printStackTrace(); 

内每catch()块，使它们发生时，你可以看到在控制台的错误。

没有人喜欢在控制台中的红色消息，但隐藏它们不会帮助。始终打印错误或记录它们，或者两者皆有:)