Java线程绑定异常与已使用的地址结合使用错误（使用套接字的客户端服务器）

Question

此程序中有两个文件（客户端文件，服务器文件），它们应该能够相互发送和接收消息（utf-8字符串）。 每个文件都有一个线程（一个线程用于客户端，一个线程用于服务器）

客户端和服务器在本地主机上使用端口号连接（在命令提示符/ mac终端窗口上键入时，该端口号应为相同的端口号）

但是，服务器应该仅在收到来自客户端的消息后才向所有其他客户端发送消息。 换句话说，如果客户端将消息发送到服务器，则服务器无法将该消息发送回相同的客户端-它只能将消息发送到不同的客户端。

另一种说法是：连接客户端后，它可以将消息发送到服务器。 它还将从服务器接收从其他连接的客户端发送的所有消息（而不是从其自身发送的消息）。

在运行时，应该只有一台服务器（mac终端/命令提示符窗口），但是可以有多个/无限数量的客户端（mac终端/命令提示符窗口）

错误的屏幕快照（服务器端）：

错误的屏幕截图（客户端）：

ChatServer.java代码：

import java.io.*;
import java.net.*;
import java.util.*;
import static java.nio.charset.StandardCharsets.*;
public class ChatServer
{
    private static Socket socket;

    public static void main(String args[])
    {
        Thread ChatServer1 = new Thread () 
        {
            public void run ()
            {   
                System.out.println("Server thread is now running");
                try
                {
                    int port_number1 = 0;
                    int numberOfClients = 0;
                    boolean KeepRunning = true;
                    if(args.length>0)
                    {
                        port_number1 = Integer.valueOf(args[0]);
                    }
                    System.out.println("Waiting for connections on port " + port_number1);

                    try 
                    {
                        ServerSocket serverSocket = new ServerSocket(port_number1);

                    } 
                    catch (IOException e)
                    {
                        e.printStackTrace();
                    }
                    System.out.println( "Listening for connections on port: " + ( port_number1 ) );
                    while(KeepRunning)
                    {
                        ServerSocket serverSocket = new ServerSocket(port_number1);
                        //create a list of clients
                        ArrayList<String> ListOfClients = new ArrayList<String>();

                        //connect to client
                        socket = serverSocket.accept();  

                        //add new client to the list, is this the right way to add a new client? or should it be in a for loop or something?
                        ListOfClients.add("new client");
                        numberOfClients += 1;

                        System.out.println("A client has connected. Waiting for message...");
                        ListOfClients.add("new client" + numberOfClients);

                        //reading encoded utf-8 message from client, decoding from utf-8 format 
                        String MessageFromClientEncodedUTF8 = "";
                        BufferedReader BufReader1 = new BufferedReader(new InputStreamReader(socket.getInputStream(), "UTF-8"));  
                        String MessageFromClientDecodedFromUTF8 = BufReader1.readLine();
                        byte[] bytes = MessageFromClientEncodedUTF8.getBytes("UTF-8"); 
                        String MessageFromClientDecodedUTF8 = new String(bytes, "UTF-8");


                        //relaying message to every other client besides the one it was from

                        for (int i = 0; i < ListOfClients.size(); i++)
                        {
                            if(ListOfClients.get(i)!="new client")
                            {
                                   String newmessage = null;
                                   String returnMessage = newmessage;
                                   OutputStream os = socket.getOutputStream();
                                   OutputStreamWriter osw = new OutputStreamWriter(os);
                                   BufferedWriter bw = new BufferedWriter(osw);
                                   bw.write(returnMessage + "\n");
                                   System.out.println("Message sent to client: "+returnMessage);
                                   bw.flush();
                            }
                        }

                    }
                } 
                catch (IOException e) 
                {
                    e.printStackTrace();
                }
                finally
                {
                    try 
                    {
                        if (socket != null)
                        {
                            socket.close ();
                        }

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

            }
        };
        ChatServer1.start();
    }
}

ChatClient.java代码：

import java.io.*;
import java.net.*;
import java.util.*;
import static java.nio.charset.StandardCharsets.*;
public class ChatClient
{
    private static Socket Socket;
    static int numberOfClients = 0;
    public static void main(String args[]) 
    {
              //If I wanted to create multiple clients, would this code go here? OR should the new thread creation be outside the while(true) loop?
              while (true)
              {
                  String host = "localhost";
                  int numberOfClients = 0;
                  Thread ChatClient1 = new Thread ()
                  {
                      public void run()
                      {   
                          try
                          {
                              //Client begins, gets port number, listens, connects, prints out messages from other clients
                              int port = 0;
                              int port_1number1 = 0;
                              int numberofmessages = 0;
                              String[] messagessentbyotherclients = null;
                              System.out.println("Try block begins..");
                              System.out.println("Chat client is running");
                              String port_number1= args[0];
                              System.out.println("Port number is: " + port_number1);
                              if(args.length>0)
                              {
                                  port = Integer.valueOf(port_number1);
                              }
                              System.out.println("Listening for connections..");
                              System.out.println( "Listening on port: " + port_number1 );
                              Socket.connect(null);
                              System.out.println("Client has connected to the server");
                              for(int i = 0; i < numberOfClients; i++)
                              {
                                  System.out.println(messagessentbyotherclients);
                              }

                              //client creates new message from standard input
                              OutputStream os = Socket.getOutputStream();
                              OutputStreamWriter osw = new OutputStreamWriter(os);
                              BufferedWriter bw = new BufferedWriter(osw);

                              //creating message to send from standard input
                              String newmessage = "";
                              try   
                              {
                                  // input the message from standard input encoded in UTF-8 string format
                                  BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
                                  String line = "";
                                  System.out.println( "Standard input (press enter then control D when finished): " );
                                  while( (line= input.readLine()) != null )     
                                  {
                                      newmessage += line + " ";
                                      input=null;
                                  }
                              }
                              catch ( Exception e )
                              {
                                  System.out.println( e.getMessage() );
                              }
                              //Sending the message to server
                              String sendMessage = newmessage;
                              bw.write(sendMessage + "\n");
                              bw.flush();
                              System.out.println("Message sent to server: "+sendMessage);
                          } 
                          catch (IOException e)
                          {
                            e.printStackTrace();
                          }
                      }
                  };
                  ChatClient1.start();
        }
    }
}

这两个错误已经被讨论过很多次了，我听说答案是将套接字放入一个循环中，而该循环已经在（while循环中）了。

我的问题是：有没有办法在运行之前找到错误？ 每当我编译程序时，eclipse都不会出现任何错误，但是当我在命令提示符窗口/ mac终端中运行它时，它的确告诉我有问题。 或者也许有一行代码我正在忽略？

Answer 1

ServerSocket serverSocket = new ServerSocket(port_number1);

在while循环之前将其放置一次。