我对所有这些联网的东西都是新手。我最近一直在用Java开发客户端和服务器。客户端按照它应该连接到服务器，并且还从服务器获得响应。只要客户端和服务器在同一网络中的计算机上运行，一切都可以正常工作。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，客户端就是找不到服务器。
我该怎么做才能让客户端从另一个网络连接到服务器？这是否意味着我可以连接到来自世界各地的服务器？
在这里你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);
}
}
}
}
在这里你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()));
}
}
正如您所知，每台计算机都有一个ip地址和一个端口号，服务器就是一种类型的计算机。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，你应该为你的计算机提供静态ip。这样，您的客户端应用程序始终知道应该使用哪个端口和哪个IP地址连接到服务器应用程序。如果你想测试，并且不想为服务器或静态Ip地址付费，请在客户端应用程序中提供用户的Ip地址和端口，我认为你可以在2台不同的计算机上运行你的应用程序，但值得一提的是，你的根程序设置可能会影响你的连接。