java中mysql的Socket编程

Question

我已经创建了客户端和服务器页面。我需要连接到数据库，但当我首先运行服务器时，它正在工作。启动服务器，然后运行客户端页面，得到的错误是display severy:null。我不知道为什么。我在下面附上了代码。我的客户端页面有问题。有什么不对劲吗？我试过的东西附在下面。请给出解决方案，谢谢

出版商。java

public class publisher {
    
    String id;
    String pname;
    String price;
    String qty;

public static void main(String args[])
{
   new publisher(); 

}
}

服务器。java

import java.io.*;
import java.sql.*;
import java.net.*;
import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.table.DefaultTableModel;

public class Server extends Thread {

    Statement stmt=null;
    Vector records = new Vector(10,10);
    ResultSet rs = null;
    ServerSocket server = null;
    Socket client = null;
    Connection con = null;
    ObjectOutputStream out =null;
    String str = null;
    publisher pub = null;
    
    public Server()
    {
        try {
            server = new ServerSocket(1700);
            System.out.println("Starting the Server");
            start();
        } catch (IOException ex) {
            Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
        }
        
    }
    
    public void run()
    {
        while(true)
        {
            try {
                int CC;
                client = server.accept();
                System.out.println("Connection accepted");   
                out = new ObjectOutputStream(client.getOutputStream());
                System.out.println("OutputStream received");
                try {
                    Class.forName("com.mysql.jdbc.Driver");
                    con = DriverManager.getConnection("jdbc:mysql://localhost/smobile", "root","");
                    stmt = con.createStatement();
                    rs = stmt.executeQuery("select * from products");
                    records.removeAllElements();

            ResultSetMetaData RSMD = rs.getMetaData();
            CC = RSMD.getColumnCount();
                    
                    
                    
                    while(rs.next())
                    {
                        pub = new publisher();
                        pub.id = rs.getString(1);
                        pub.pname = rs.getString(2);
                        pub.price = rs.getString(3);
                        pub.qty = rs.getString(4);
                        records.addElement(pub);
                        System.out.println("row returned");
                    }

                    out.writeObject(records);
                    out.close();
                    System.out.println("String returned");
                    
                    
                } catch (ClassNotFoundException ex) {
                    Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
                } catch (SQLException ex) {
                    Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
                }
          
                 
                 
                 
                 
            } catch (IOException ex) {
                Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
            }
            
        }
    }
    public static void main(String args[])
{
   new Server(); 

}



Client.java

     String str = "";
           ResultSet rs;
           Vector records;
           publisher pub = null;
           int a = 0;
           ObjectInputStream br = null;
           Connection con;
           PreparedStatement pst;

           private void table_update() 
{
            int i = 0;
                 Socket socket1;
            try {
                socket1 = new Socket( "192.168.225.1", 1700);
                 System.out.println("client is now connected with server");
            
                br = new ObjectInputStream(socket1.getInputStream());
                records = (Vector)br.readObject();
     
                DefaultTableModel DFT = (DefaultTableModel) jTable1.getModel();
                DFT.setRowCount(0);
    
                while (i < records.size()) {
                    Vector v2 = new Vector();
                     pub = (publisher)records.elementAt(i);
                
                        v2.add(pub.id);
                        v2.add(pub.pname);
                        v2.add(pub.price);
                        v2.add(pub.qty);
                           i++;
                        DFT.addRow(v2);
                        
                    }
    
                    
                } catch (IOException ex) {
                Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex);
            } catch (ClassNotFoundException ex) {
                Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex);
            }

显示错误

Client table_update
SEVERE: null
java.io.EOFException
    at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:3014)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1575)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:464)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:422)
    at Client.table_update(Client.java:62)
    at Client.<init>(Client.java:22)