Question

我正在创建一个局域网游戏，它接受字符串并从结构化英语中解析它们并在网格上显示它们。我已经创建了服务器和客户端，它可以工作但我有一些问题。当我发送一个字符串时，它不会立即出现在另一台机器上。由于某种原因，一旦另一台机器发送了一些东西，该字符串才会被发送到另一台机器。我不知道为什么会这样。你能帮我找一下它为什么不马上发送。感谢

服务器代码：

import java.awt.Point;
import javax.swing.*;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
public class studentServer{
static ServerSocket serverSocket;
static Socket socket;
static PrintWriter printWriter;
static BufferedReader bufferedReader;
static Thread thread;
Console console = new Console();


public ServerPlayergameMain gm;
    public static void main(String args[]) throws Exception{
}
public void run(String commandMessage){
    while(true){
        try{
            printWriter.println(commandMessage+"\n");
            String input = bufferedReader.readLine();//reads the input from textfield
            console.readLine("Client message: "+input);//Append to TextArea
        }catch(Exception e){}
    }
}
    public void serverStartActionPerformed() {
    System.out.println("Server has started!");
    try{
        serverSocket = new ServerSocket (8888); // socket for the server
        socket = serverSocket.accept(); // waiting for socket to accept client
        JOptionPane.showMessageDialog(null, "Your opponent has connected!", "Opponent Connection!", JOptionPane.INFORMATION_MESSAGE);
        gm = new ServerPlayergameMain();
        gm.setVisible(true);
        bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream())); // reads line from input streamer
        printWriter = new PrintWriter(socket.getOutputStream(),true);
    }catch(IOException | HeadlessException e){
        System.out.println("Server not running!"); //print message if server is not running
    }
}
}

客户代码：

import java.io.*;
import java.net.*;
import javax.swing.JOptionPane;
public class StudentClient {
static Socket socket;
static PrintWriter printWriter;
static BufferedReader bufferedReader;
static Thread thread;
Console console = new Console();


public ClientPlayergameMain gm;

public void Clients(String address) {
    try{
        socket=new Socket("localhost",8888);//Socket for client
        //below line reads input from InputStreamReader
        bufferedReader=new BufferedReader(new InputStreamReader(socket.getInputStream()));
        //below line writes output to OutPutStream
        printWriter=new PrintWriter(socket.getOutputStream(),true);
        JOptionPane.showMessageDialog(null, "Connected to server successfully", "Success", JOptionPane.INFORMATION_MESSAGE);
        gm = new ClientPlayergameMain();
        gm.setVisible(true);
        System.out.println("Connected");//debug code
    }catch(Exception e){
       JOptionPane.showMessageDialog(null, "No Connection to server", "Error", JOptionPane.ERROR_MESSAGE);
        System.out.println("Not Connected");
    }    
}
public static void run(String commandMessage){
        while(true){
            try{
                printWriter.println(commandMessage+"\n");
                String input = bufferedReader.readLine();
                System.out.println("From server:" +input);
            }catch(Exception e) {}
        }
}
}

代码有效，但我不知道为什么其他机器有条件发送东西。

感谢您的时间。

Answer 1

您是否在每次写/打印后尝试printWriter.flush()？

Answer 2

您的代码中存在许多编译问题。缺少一些类和对象需要解决。

我仍然试图弄清楚这个问题。

可能是原因：

在\n语句中发送换行符printWriter.println(commandMessage+"\n");，只需删除\n。
客户端和服务器都在printWriter.println(commandMessage+"\n");语句中首先写入，在任何类中使其最后

以下是代码：

<强> StudentServer.java：

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

public class StudentServer {
    static ServerSocket serverSocket;
    static Socket socket;
    static PrintWriter printWriter;
    static BufferedReader bufferedReader;
    static Thread thread;

    public static void main(String args[]) throws Exception {
        StudentServer studentServer = new StudentServer();
        studentServer.serverStartActionPerformed();
        studentServer.run("server");
    }

    public void run(String commandMessage) {
        if (true) {
            try {
                printWriter.println(commandMessage);
                String input = bufferedReader.readLine();// reads the input from textfield
                System.out.println("Client message: " + input);// Append to TextArea
            } catch (Exception e) {
            }
        }
    }

    public void serverStartActionPerformed() {
        System.out.println("Server has started!");
        try {
            serverSocket = new ServerSocket(8888); // socket for the server
            socket = serverSocket.accept(); // waiting for socket to accept client
            bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream())); // reads
                                                                                                 // line
                                                                                                 // from
                                                                                                 // input
                                                                                                 // streamer
            printWriter = new PrintWriter(socket.getOutputStream(), true);
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("Server not running!"); // print message if server is not running
        }
    }
}

<强> StudentClient.java：

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

public class StudentClient {
    static Socket socket;
    static PrintWriter printWriter;
    static BufferedReader bufferedReader;
    static Thread thread;

    public void clients() {
        try {
            socket = new Socket("localhost", 8888);// Socket for client
            // below line reads input from InputStreamReader
            bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            // below line writes output to OutPutStream
            printWriter = new PrintWriter(socket.getOutputStream(), true);
            System.out.println("Connected");// debug code
        } catch (Exception e) {
            System.out.println("Not Connected");
        }
    }

    public void run(String commandMessage) {
        if (true) {
            try {
                String input = bufferedReader.readLine();
                System.out.println("From server:" + input);
                printWriter.println(commandMessage);
            } catch (Exception e) {
            }
        }
    }

    public static void main(String args[]) throws Exception {
        StudentClient studentClient = new StudentClient();
        studentClient.clients();
        studentClient.run("client");
    }
}

Answer 3

Braj指出，有很多小问题。主要的一个是服务器端的顺序：

   serverSocket = new ServerSocket (8888); // socket for the server
   socket = serverSocket.accept(); // BLOCKS waiting for socket to accept client
   // ..
   printWriter = new PrintWriter(socket.getOutputStream(),true);

这意味着用于写入客户端的printWriter在服务器已经侦听，阻止等待并从客户端接受连接之后才会存在。

如果您希望打开连接以进行读写而不希望从客户端发送任何内容，请从客户端发送握手。您可以复制SMTP，并使用HELO <myname>。这甚至告诉服务器谁在呼叫。

进一步阅读后更新：

我总是像你一样完成，并使用了在客户端使用getOutputStream()时发生的隐式连接。但是，Socket允许您使用Socket#connect()手动连接现有套接字。尝试一下，也许它会比你握手更好。

Java服务器/客户端字符串延迟

3 个答案: