使用多线程在 Java 服务器中同时监听两个端口

Listening to two ports simultaneously in Java server using multithreading(使用多线程在 Java 服务器中同时监听两个端口)

问题描述

我正在构建一个简单的 Java 服务器，它使用两个 ServerSocket 实例同时监听两个端口上的客户端请求.这是服务器的代码:

I am building a simple Java server which simultaneously listens for client request on two ports simultaneously using two ServerSocket instances. Here is the code for Server:

import java.io.PrintWriter;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

class Socket1 implements Runnable
{
    public void run()
    {
        try
        {
            ServerSocket serverSock=new ServerSocket(5000);
            while(true)
            {
                Socket sock=serverSock.accept();
                PrintWriter writer=new PrintWriter(sock.getOutputStream());
                String text="Welcome to Port 5000";
                writer.println(text);
            }
        }
        catch(Exception e)
        {
            System.out.println("Error");
        }
    }
}

class Socket2 implements Runnable
{
    public void run()
    {
        try
        {
            ServerSocket serverSock=new ServerSocket(3000);
            while(true)
            {
                Socket sock=serverSock.accept();
                PrintWriter writer=new PrintWriter(sock.getOutputStream());
                String text="Welcome to Port 3000";
                writer.println(text);
            }
        }
        catch(Exception e)
        {
            System.out.println("Error");
        }
    }
}

public class Server
{
    public static void main(String[] args)
    {
        Socket1 s1=new Socket1();
        Socket2 s2=new Socket2();
        Thread t1=new Thread(s1);
        Thread t2=new Thread(s2);
        t1.start();
        t2.start();
    }
} 

现在为 Client1 编码:

Now code for Client1:

import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.net.Socket;

public class Client1
{
    public static void main(String[] args)
    {
        try
        {
            Socket s=new Socket("127.0.0.1", 5000);
            InputStreamReader streamReader=new InputStreamReader(s.getInputStream());
            BufferedReader reader=new BufferedReader(streamReader);
            String text=reader.readLine();
            System.out.println(text);
            reader.close();
        }
        catch(Exception e)
        {
            System.out.println("Error");
        }
    }
}

Client2 包含与 Client1 相同的代码，唯一的区别是它尝试连接到端口 3000.现在，我首先使用命令提示符执行 Server.java.当服务器阻塞时，我打开两个单独的命令提示符并在一个命令提示符上执行 Client1.java，在另一个命令提示符上执行 Client2.java.但是，两个客户端都进入阻塞状态，我没有得到任何输出.知道如何解决这个问题吗?

Client2 contains the same code as Client1, the only difference being that it tries to connect to port 3000. Now, I execute Server.java first using command prompt. While the server blocks, I open two separate command prompts and execute Client1.java on one command prompt and Client2.java on the other command prompt. But, both clients go to blocking state and I get no output. Any idea how to solve this ?

推荐答案

PrintWriter 被默认缓冲.在 writer.println() 之后添加一个 writer.flush() (或者更好的是一个 close() 因为你不再使用流了)代码>.

PrintWriter is buffered by defaut. Add a writer.flush() (or even better a close() since you're not using the stream anymore) after writer.println().

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