Question

服务器端程序

import java.net.*;
import java.io.*;

public class GreetingServer extends Thread
{
    private ServerSocket serverSocket;
    public GreetingServer(int port) throws IOException
    {
        serverSocket = new ServerSocket(port);
        serverSocket.setSoTimeout(10000);
    }

    public void run()
    {
        while(true)
        {
            try
            {
                System.out.println("Waiting for client on port " +
                        serverSocket.getLocalPort() + "...");
                Socket server = serverSocket.accept();
                System.out.println("Just connected to "
                        + server.getRemoteSocketAddress());
                DataInputStream in =
                    new DataInputStream(server.getInputStream());
                System.out.println(in.readUTF());
                DataOutputStream out =
                    new DataOutputStream(server.getOutputStream());
                out.writeUTF("Thank you for connecting to "
                        + server.getLocalSocketAddress() + "\nGoodbye!");
                server.close();
            }catch(SocketTimeoutException s)
            {
                System.out.println("Socket timed out!");
                break;
            }catch(IOException e)
            {
                e.printStackTrace();
                break;
            }
        }
    }
    public static void main(String [] args)
    {
        int port = Integer.parseInt(args[0]);
        try
        {
            Thread t = new GreetingServer(port);
            t.start();
        }catch(IOException e)
        {
            e.printStackTrace();
        }
    }
}

客户端计划

import java.net.*;
import java.io.*;

public class GreetingClient
{
    public static void main(String [] args)
    {
        String serverName = args[0];
        int port = Integer.parseInt(args[1]);
        try
        {
            System.out.println("Connecting to " + serverName
                    + " on port " + port);
            Socket client = new Socket(serverName, port);
            System.out.println("Just connected to "
                    + client.getRemoteSocketAddress());
            OutputStream outToServer = client.getOutputStream();
            DataOutputStream out = new DataOutputStream(outToServer);

            out.writeUTF("Hello from " + client.getLocalSocketAddress());
            InputStream inFromServer = client.getInputStream();
            DataInputStream in =
                new DataInputStream(inFromServer);
            System.out.println("Server says " + in.readUTF());
            client.close();
        }catch(IOException e)
        {
            e.printStackTrace();
        }
    }
}

如果可能的话，任何文件都会发送和收到。我尝试了很多，但我无法弄清楚为什么使用不同的端口和文件操作。

Answer 1

为什么每次连接时此套接字程序都会使用不同的端口它呢

这是操作系统在连接未绑定套接字时所执行的操作。它选择一些可用的源端口（称为“临时端口”）并使用它。如果你想确保它选择某个端口，你需要bind套接字。

为什么这个套接字程序每次连接都会占用不同的端口

1 个答案: