套接字编程中"helloworld"服务器和客户端程序中的异常

Question

我在运行客户端程序时收到此错误。我还无法认识到这个问题。我已经更改了端口号，但没有用。我看到了以前关于同一错误的帖子，但我没有弄清楚。

服务器.java

import java.io.*;
import java.net.*;
class Server{
 public static void main(String argv[]) throws Exception 
 {
   String clientSentence;
   String capitalizedSentence;
   ServerSocket welcomeSocket = new ServerSocket(8080);
   while (true) 
   {
      Socket connectionSocket = welcomeSocket.accept();
       BufferedReader inFromClient = new BufferedReader(new 
      InputStreamReader(connectionSocket.getInputStream()));
       DataOutputStream outToClient = new 
       DataOutputStream(connectionSocket.getOutputStream());
       clientSentence = inFromClient.readLine();
        System.out.println("Received: " + clientSentence);
        capitalizedSentence = clientSentence.toUpperCase() + 'n';
         outToClient.writeBytes(capitalizedSentence);
     }
  }
  }

客户端.java

import java.io.*;
import java.net.*;
class Client
{
 public static void main(String argv[]) throws Exception 
 {
      String sentence;
      String modifiedSentence;
      BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
      Socket clientSocket = new Socket("localhost", 8080);    
      DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());
      BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
      sentence = inFromUser.readLine();
      outToServer.writeBytes(sentence + 'n');
      modifiedSentence = inFromServer.readLine();
      System.out.println("FROM SERVER: " + modifiedSentence);
      clientSocket.close();
 }
 }

我在运行客户端时收到错误.java

Exception in thread "main" java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at Client.main(Client.java:11)

任何人都可以帮助解决此错误吗？

Answer 1

客户端和服务器程序对我来说运行得很好。

1. 您能否检查该端口上是否已经有一些进程在侦听。