java - 如何使我的 Java 服务器可供世界各地使用？

Question

我对所有网络知识都很陌生。我最近一直在用Java开发客户端和服务器。客户端按其应有的方式连接到服务器，并从服务器获取响应。只要客户端和服务器在同一网络中的计算机上运行，​​一切都工作正常。当我尝试从与服务器不在同一网络中的计算机连接到服务器时，客户端找不到服务器。

我该怎么做才能使客户端可以从另一个网络连接到服务器？这是否意味着我可以从世界各地连接到服务器？

在这里您可以找到我的服务器代码:

    package zwei;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {

    public static int Port = 55571;

    static ServerSocket ServerSocket;
    static Socket ClientSocket;

    static PrintWriter out;
    static BufferedReader in;

    public static void main(String[] args) throws IOException{
            handleConnection(Port);

    }


    static void handleConnection(int port) throws IOException {
        ServerSocket = new ServerSocket(port);
        System.out.println("Waiting for connections...");

        ClientSocket = ServerSocket.accept();
        System.out.println("Connected to Client!");

        out = new PrintWriter(new OutputStreamWriter(ClientSocket.getOutputStream()));
        in = new BufferedReader(new InputStreamReader(ClientSocket.getInputStream()));

        while(true) {
            try {
                    char[] buffer = new char[200];
                    int AnzahlZeichen = in.read(buffer, 0, 200);
                    String message = new String(buffer, 0, AnzahlZeichen);
                    System.out.println("[Client] " + message); 

                    out.print("Dear Client, I got your message! [ -" + message + "- ]");
                    out.flush();

                    if (message.equals("DISCONNECT")) {
                        System.out.println("Client disconnected");
                        ServerSocket.close();
                        ClientSocket.close();
                        handleConnection(Port);
                    }
                }
            catch(Exception e) {
                System.out.println("Client disconnected");
                ServerSocket.close();
                ClientSocket.close();
                handleConnection(Port);
            }

        }

    }

}

在这里您可以找到客户端的代码:

package zwei;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;

public class Client extends JFrame{

    static int port = 55570;
    static String ServerAdress = ""; //Here I put the IP-Adress of the computer the server is running on

    static Socket ClientSocket;

    static PrintWriter out;
    static BufferedReader in;

    JTextField EnterMessage;
    JButton SendMessage;

    Client(){
         this.setLayout(null);
         this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         this.setVisible(true);
         this.setResizable(false);
         this.setSize(700, 700);
         //this.setTitle("Vokabeltrainer");

         EnterMessage = new JTextField();
         EnterMessage.setBounds(50, 50, 500, 50);
         this.add(EnterMessage);

         SendMessage = new JButton("send");
         SendMessage.setBounds(50, 150, 100, 100);
         SendMessage.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    SendMessageToServer(EnterMessage.getText());
                    ReceiveMessageFromServer();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }

            }});
         this.add(SendMessage);
    }

    private void connectToServer(String ServerAdress, int port) throws IOException {

        try {
            this.ClientSocket = new Socket(ServerAdress,port);
            System.out.println("Successfully established a connection to the server on port " + port + " .");
            }

        catch(Exception e) {
            System.out.println("An error occured while trying to connect to the server!");
            System.out.println("");
            e.printStackTrace();
        }
    }

    private void SendMessageToServer(String Nachricht) throws IOException {
        out = new PrintWriter(new OutputStreamWriter(ClientSocket.getOutputStream()));
        out.print(Nachricht);
        out.flush();
    }

    private void ReceiveMessageFromServer() throws IOException{
        in = new BufferedReader(new InputStreamReader(ClientSocket.getInputStream()));
        char[] buffer = new char[200];
        int AnzahlZeichen = in.read(buffer, 0, 200);
        String message = new String(buffer, 0, AnzahlZeichen);
        System.out.println("[Server] " + message); 
    }

    public static void main(String[] args) throws Exception { 
        Client client = new Client();
        client.connectToServer(ServerAdress, port);
        //in = new BufferedReader(new InputStreamReader(ClientSocket.getInputStream()));


    }

}

Answer 1

如您所知，每台计算机都有一个 IP 地址和端口号，服务器是一种计算机。如果你想让你的应用程序工作，你应该有一个可以运行java的服务器，或者如果你只需要测试，你应该有你的计算机的静态IP。这样，您的客户端应用程序始终知道应使用哪个端口和哪个 IP 地址来连接到您的服务器应用程序。如果您想测试并且不想支付服务器或静态IP地址费用，请在客户端应用程序中提供用户的IP地址和端口，我认为您可以在两台不同的计算机上运行您的应用程序，但值得一提的是您的设置rooter 可能会影响您的连接。