UDP示例给出java.lang.ClassNotFoundException：PackageName.foo异常；如何修复？

Question

我是UDP协议的新手，我想学习一个很好的例子。我终于找到了一个很好的示例，但它给出了java.lang.ClassNotFoundException:packageName.student异常

我首先运行服务器，然后运行客户端。

客户端输出：

来自客户端的消息
来自服务器的响应：谢谢您的消息-------------

上面的----大行

服务器输出：

java.lang.ClassNotFoundexception:ex_udp_client.student在java.net.urlClassLoader$1上运行(urlClassLoader.java:366)在java.net.urlClassLoader$1上运行(urlClassLoader.java:355)在java.security.accessController.doprivileged（本机方法）在java.net.urlClassLoader.findClass（本机方法）在java.net.urlClassLoader.java:354)在dp_server.udpsocketserver.createandlistensocket(udpsocketserver.java:40)在ex_udp_server.udpsocketserver.main（udpsocketserver.java:72)上生成成功（总时间：6秒）

我认为在这一行抛出的异常:
student student=（student）is.readObject（）；

如何修复？

复制到客户端和服务器包的可序列化类

import java.io.Serializable;

public class Student implements Serializable
{

   public Student(int id, String name, String address1)
   {
      this.id = id;
      this.name = name;
      this.addressLine = address1;
   }
   private static final long serialVersionUID = 1L;
   private int id;
   private String name;
   private String addressLine;

   public int getId()
   {
      return id;
   }

   public void setId(int id)
   {
      this.id = id;
   }

   public String getName()
   {
      return name;
   }

   public void setName(String name)
   {
      this.name = name;
   }

   public String getAddressLine()
   {
      return addressLine;
   }

   public void setAddressLine(String addressLine)
   {
      this.addressLine = addressLine;
   }

   public String toString()
   {
      return "Id = " + getId() + " Name = " + getName() + " Address = " + getAddressLine();
   }
}

Server类

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

public class UDPSocketServer
{

   DatagramSocket socket = null;

   public UDPSocketServer()
   {
   }

   public void createAndListenSocket()
   {
      try
      {
         socket = new DatagramSocket(9876);
         byte[] incomingData = new byte[1024];

         while (true)
         {
            DatagramPacket incomingPacket = new DatagramPacket(incomingData, incomingData.length);
            socket.receive(incomingPacket);
            byte[] data = incomingPacket.getData();
            ByteArrayInputStream in = new ByteArrayInputStream(data);
            ObjectInputStream is = new ObjectInputStream(in);
            try
            {
               Student student = (Student) is.readObject();
               System.out.println("Student object received = " + student);
            } catch (ClassNotFoundException e)
            {
               e.printStackTrace();
            }
            InetAddress IPAddress = incomingPacket.getAddress();
            int port = incomingPacket.getPort();
            String reply = "Thank you for the message";
            byte[] replyBytea = reply.getBytes();
            DatagramPacket replyPacket =
                    new DatagramPacket(replyBytea, replyBytea.length, IPAddress, port);
            socket.send(replyPacket);
            Thread.sleep(2000);
            System.exit(0);
         }

      } catch (SocketException e)
      {
         e.printStackTrace();
      } catch (IOException i)
      {
         i.printStackTrace();
      } catch (InterruptedException e)
      {
         e.printStackTrace();
      }
   }

   public static void main(String[] args)
   {
      UDPSocketServer server = new UDPSocketServer();
      server.createAndListenSocket();
   }
}

客户端类

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.net.*;

public class UDPSocketClient
{

   DatagramSocket Socket;

   public UDPSocketClient()
   {
   }

   public void createAndListenSocket()
   {
      try
      {

         Socket = new DatagramSocket();
         InetAddress IPAddress = InetAddress.getByName("localhost");
         byte[] incomingData = new byte[1024];
         Student student = new Student(1, "Bijoy", "Kerala");
         ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
         ObjectOutputStream os = new ObjectOutputStream(outputStream);
         os.writeObject(student);
         byte[] data = outputStream.toByteArray();
         DatagramPacket sendPacket = new DatagramPacket(data, data.length, IPAddress, 9876);
         Socket.send(sendPacket);
         System.out.println("Message sent from client");
         DatagramPacket incomingPacket = new DatagramPacket(incomingData, incomingData.length);
         Socket.receive(incomingPacket);
         String response = new String(incomingPacket.getData());
         System.out.println("Response from server:" + response);
         Thread.sleep(2000);

      } catch (UnknownHostException e)
      {
         e.printStackTrace();
      } catch (SocketException e)
      {
         e.printStackTrace();
      } catch (IOException e)
      {
         e.printStackTrace();
      } catch (InterruptedException e)
      {
         e.printStackTrace();
      }
   }

   public static void main(String[] args)
   {
      UDPSocketClient client = new UDPSocketClient();
      client.createAndListenSocket();
   }
}

Answer 1

您是在服务器中还是在客户端中得到这个异常？
在这两个中的任何一个中，都意味着在运行时（在客户端或服务器中）没有
这个类。
我的意思是，类路径上没有它。

Answer 2

复制到客户端和服务器包的可序列化类

这就是问题所在。一个名为client.student的类与server.student不同，不管源代码怎么说。您需要在适当的目录中拥有该类的一个副本，并将.class文件部署到服务器和客户端。