Java - 线程、Swing 和 ServerSocket

Question

我知道我知道，到处都有一百万个问题和答案。大量关于它的详细文章，几种类型的示例。在过去的几个小时里，我一直在阅读它，但这并没有起到作用。我问这个的原因是因为我仍然不明白我需要做什么显然因为我的代码仍然无法正常工作。我了解 Swing 如何与 EDT 一起工作，如果我要使用 ServerSocket 的 accept() 方法，我将需要为 Swing 启动一个新线程（我认为？）。当我运行我的代码时，窗口只是打开并冻结。 我的问题是有人可以看看我的代码，告诉我我做错了什么，然后像我只有半个大脑一样向我解释它吗？（因为那是我觉得。:P)

以下是我已经阅读过的一些地方：

• This question from SO.
• This site.
• And of course the Oracle's explanation of swing and threads.
• 以及其他一些随机网站。

Main.class

package com.sever.core;

import java.io.IOException;
import java.net.Socket;
import java.util.Scanner;

import javax.swing.SwingUtilities;

public class Main { 

private SocketManager network;
public static void main(String[] args){

    SwingUtilities.invokeLater(new Runnable(){
        @Override
        public void run() {
            Window window = new Window();
            window.setVisible(true);
        }       
    });

    SwingUtilities.invokeLater(new Runnable(){
        @Override
        public void run() {
            Main main = new Main();
            main.run();
        }       
    });     


}

public void run(){
    network = new SocketManager(25595);

    while(true){
        try {
            network.setSocket(network.getServerSocket().accept());
            AddUser(network.getSocket());
            Thread x = new Thread(network);
            x.start();
        } catch (Exception e) {
            System.out.println("Failed to connect.");
        }
    }

}

public void AddUser(Socket s){
    try {
        Scanner input = new Scanner(s.getInputStream());
        network.addUser(input.nextLine());
    } catch (Exception e) {

    }
}
}

Window.class

package com.sever.core;

import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.*;

public class Window extends JFrame{

private int screenWidth = 800;
private int screenHeight = 600;
private Thread thread;

private JPanel window = new JPanel();
private JTextArea consle = new JTextArea("Server started....");
private JTextField input = new JTextField();
private JScrollPane consleinput = new JScrollPane(consle);

public Window(){
    this.setName("NAMEHERE - Server Software");
    setResizable(true);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setSize(screenWidth,screenHeight);  
    window.setBackground(Color.DARK_GRAY);
    window.setLayout(new BoxLayout(window, BoxLayout.Y_AXIS));

    consleSetup();
    addComponets();
}

private void addComponets(){
    add(window);
    window.add(consleinput);
    window.add(input);
}

private void consleSetup(){
    consle.setEditable(false);
    consle.setLineWrap(true);
    consle.setBorder(BorderFactory.createEmptyBorder(3,3,3,3)); 
    consleinput.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
    input.setMaximumSize(new             Dimension(Integer.MAX_VALUE,input.getPreferredSize().height));
}

private void addListeners(){
    input.addActionListener(new ActLis());
    input.setActionCommand("input");
}

}

SocketManager.class

package com.sever.core;

import java.io.*;
import java.net.*;
import java.util.ArrayList;

public class SocketManager implements Runnable{

private Socket sock;
private ServerSocket sersoc;
private PrintWriter output;
private BufferedReader input;
private Thread thread;

public ArrayList<Socket> currentConnections = new ArrayList<Socket>();
public ArrayList<String> currentUsers = new ArrayList<String>();


public SocketManager(String ip, int port){
    try{
        sock = new Socket(ip,port);
        PrintWriter output = new PrintWriter(sock.getOutputStream());
        BufferedReader input = new BufferedReader(
                new InputStreamReader(sock.getInputStream()));
        System.out.println("Server: socket started.");
    }catch(Exception e){
        System.out.println("Server: Socket failed to connect.\n");
    }
}

public SocketManager(int port){
    try {
        sersoc = new ServerSocket(port);

    } catch (IOException e) {
        System.out.println("Server: Socket failed to connect.\n");
    }
}

public SocketManager(Socket socket){
    this.sock = socket;

    try{
        output = new PrintWriter(sock.getOutputStream());
        input = new BufferedReader(
                new InputStreamReader(sock.getInputStream()));
    }catch(Exception e){

    }
}

public synchronized void checkConnetion(){
    if(!sock.isConnected()){
        for(int x = 0; x <= currentConnections.size(); x++){
            if(currentConnections.get(x) == sock){
                currentConnections.remove(x);
                System.out.println("Server: Disconnecting from: " + currentConnections.get(x) + "\n");
            }
        }
    }
}

public synchronized Socket getSocket(){
    return sock;
}

public synchronized ServerSocket getServerSocket(){
    return sersoc;
}

public synchronized void setSocket(Socket s){
    System.out.println("Setting socket to: " + s.getInetAddress());
    sock = s;
}

public synchronized void addSocket(Socket s){
    currentConnections.add(s);
}

public synchronized void addUser(String u){
    currentUsers.add(u);
}

public synchronized ArrayList<Socket> getConnections(){
    return currentConnections;
}

public synchronized ArrayList<String> getUsers(){
    return currentUsers;
}

public synchronized void send(String data){
    try{
        output.println(data);
    }catch(Exception e){

    }
}

public synchronized void close(){
    try{
        sock.close();
    }catch(Exception e){

    }
    output = null;
    input = null;
    System.gc();
}

public synchronized boolean isConnected(){
    return (sock == null) ? false : (sock.isConnected() && !sock.isClosed());
}

@Override
public void run() {
    System.out.println("Is runing.");
    while(true){
        try {
            checkConnetion();
            if(input.readLine().isEmpty()){ 
                return;
            }

            output.println("Server: Recived your message.");
        } catch (Exception e) {

        } finally{
            try {
                sock.close();
            } catch (Exception e) {

            }
        }
    }

}

}

ActLis.class

package com.sever.core;

import java.awt.event.*;
import javax.swing.*;

public class ActLis implements ActionListener{

private JTextField actionField;
public ActLis(){

}

public ActLis(JTextField t){
    actionField = t;
}

@Override
public void actionPerformed(ActionEvent e) {
    // TODO Auto-generated method stub
    String cmd = e.getActionCommand();

    if(cmd == "input"){

    }
}

}

--编辑--- 带有 SwingWorker 的新 Main.class

package com.sever.core;

import java.io.IOException;
import java.net.Socket;
import java.util.Scanner;

import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;

public class Main { 

private SocketManager network;
public static void main(String[] args){

    SwingUtilities.invokeLater(new Runnable(){
        @Override
        public void run() {
            Window window = new Window();
            window.setVisible(true);
        }       
    });

    SwingWorker server = new SwingWorker(){
        @Override
        protected Object doInBackground() throws Exception {
            Main main = new Main();
            main.run();
            return null;
        }

    };
    server.run();

}

public void run(){
    network = new SocketManager(25595);

    while(true){
        try {
            network.setSocket(network.getServerSocket().accept());
            AddUser(network.getSocket());
            Thread x = new Thread(network);
            x.start();
        } catch (Exception e) {
            System.out.println("Failed to connect.");
        }
    }

}

public void AddUser(Socket s){
    try {
        Scanner input = new Scanner(s.getInputStream());
        network.addUser(input.nextLine());
    } catch (Exception e) {

    }
}
}

Answer 1

您正在从 EDT 上的 Socket 读取数据。这意味着你阻止它。调用 invokeLater 只会导致您的 Runnable 在 EDT 上执行。你在 EDT 上堆积了两个调用，其中一个是你的套接字。

考虑将您的套接字移动到 SwingWorker 中，它将逐步将您的 Socker 的值返回到 GUI。

Answer 2

套接字操作块。例如，如果您调用accept，调用将不会返回，直到有人真正连接到您的程序，实际上阻塞它正在运行的线程。这就是为什么他们建议让网络在辅助线程上运行。

在您的情况下，您确实创建了一个线程，但您没有从中调用accept。

while(true) {
    try {
        // this is called on the EDT--beware!
        network.setSocket(network.getServerSocket().accept());
        AddUser(network.getSocket());
        // ... and then, everything called from x will be on the secondary thread
        Thread x = new Thread(network);
        x.start();
    } catch (Exception e) {
        System.out.println("Failed to connect.");
    }
}

这就是它冻结的原因。如果您不想阻塞 UI，则必须从辅助线程调用 accept。