java - 当点击 JButton 连接到服务器时，程序卡住

Question

我正在使用 Java 中的 TCP 进行简单的 1v1“私有(private)聊天”。目前，每当我使用 JButtons 时都会遇到问题。这是我第一次尝试使用 JButtons 和 ActionListeners，所以我不能 100% 确定这里发生了什么。

我有两个独立的服务器和客户端项目。要编译这些，它必须是两个独立的项目。

当我尝试按下按钮时，就会出现问题答:启动服务器B:连接到服务器。

按钮卡住，就像处于按下状态一样。在运行服务器并点击按钮时，要“取消按下”按钮，客户端必须尝试连接。服务器向客户端发送 MOTD，客户端应将其打印到文本窗口上。仅当服务器关闭时，它才会打印出 MOTD。再次，不知道为什么

服务器代码:

    package net.valid4life.chat;

import java.awt.Component;

public class Chat implements ActionListener {

private static final long serialVersionUID = 1L;

private static JFrame mainFrame;
private static JPanel contentPane;

private static JTextArea chatWindow;
private static JTextArea serverWindow;

private static JTextField chatBox;
private static JTextField portBox;

private static JLabel currentStatusL;
private static JLabel portl;
private static JLabel status;

private static JButton startServerButton;

private static int port = 1234;
public static final int NOT_STARTED = 0;
public static final int WAITING_FOR_CLIENT = 1;
public static final int CONNECTED = 2;
private static int currentStatus = NOT_STARTED;

public static String newLine = "\n";

public static boolean started = false;

static ServerSocket listener = null;

public static void initGUI() {

    mainFrame = new JFrame("Chat Server");

    mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    mainFrame.setBounds(100, 100, 450, 300);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    mainFrame.setContentPane(contentPane);
    contentPane.setLayout(null);

    chatWindow = new JTextArea();
    chatWindow.setLineWrap(true);
    chatWindow.setEditable(false);
    chatWindow.setBounds(220, 15, 200, 215);
    chatWindow.setAlignmentY(Component.BOTTOM_ALIGNMENT);
    contentPane.add(chatWindow);

    serverWindow = new JTextArea();
    serverWindow.setLineWrap(true);
    serverWindow.setEditable(false);
    serverWindow.setBounds(10, 150, 201, 80);
    contentPane.add(serverWindow);

    chatBox = new JTextField();
    chatBox.setBounds(221, 236, 199, 20);
    contentPane.add(chatBox);
    chatBox.setColumns(10);

    portBox = new JTextField("1234");
    portBox.setBounds(68, 37, 86, 25);
    portBox.setActionCommand("portEnter");
    portBox.setColumns(10);
    contentPane.add(portBox);

    portl = new JLabel("Port:");
    portl.setFont(new Font("Times New Roman", Font.PLAIN, 16));
    portl.setBounds(95, 20, 64, 14);
    contentPane.add(portl);

    status = new JLabel("Status:");
    status.setFont(new Font("Times New Roman", Font.PLAIN, 16));
    status.setBounds(15, 239, 46, 14);
    contentPane.add(status);

    currentStatusL = new JLabel(changeStatus(NOT_STARTED));
    currentStatusL.setFont(new Font("Times New Roman", Font.PLAIN, 16));
    currentStatusL.setBounds(60, 239, 151, 14);
    contentPane.add(currentStatusL);

    startServerButton = new JButton("Start Server");
    startServerButton.setFont(new Font("Times New Roman", Font.PLAIN, 13));
    startServerButton.setBounds(60, 96, 100, 40);
    startServerButton.setActionCommand("start");
    startServerButton.addActionListener(new Chat());
    contentPane.add(startServerButton);

    mainFrame.setVisible(true);

}

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

    initGUI();

}

public void actionPerformed(ActionEvent e) {

    if ("start".equals(e.getActionCommand())) {

        try {
            port = Integer.parseInt(portBox.getText());

            startServerButton.setEnabled(false);

            listener = new ServerSocket(port);
            changeStatus(WAITING_FOR_CLIENT);
            serverWindow.append("The server has started on "
                    + listener.getLocalPort());


        } catch (IOException e1) {
            e1.printStackTrace();
        } finally {
            try {
                startServer();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
        }




    }else
        System.out.println("YOU BROKE IT");

}

public static void startServer() throws IOException {
    try {

        System.out.println("Looking for client");
        new ServerThread(listener.accept()).start();
        System.out.println("Found client");

    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        listener.close();
    }
}

public static String changeStatus(int newStatus) {
    String newStatusText;
    switch (newStatus) {
    case 0:
        newStatusText = "Server not started.";
        break;
    case 1:
        newStatusText = "Waiting for client.";
        break;
    case 2:
        newStatusText = "Connected to client.";
        break;
    default:
        newStatusText = "Broken";
    }

    currentStatus = newStatus;
    return newStatusText;
}

public static class ServerThread extends Thread {
    private Socket socket;

    public ServerThread(Socket socket) {
        this.socket = socket;
        Chat.serverWindow.append("New Connection from:"
                + socket.getInetAddress() + Chat.newLine);
        Chat.changeStatus(CONNECTED);
    }

    public void run() {
        try {

            BufferedReader in = new BufferedReader(new InputStreamReader(
                    socket.getInputStream()));
            PrintWriter out = new PrintWriter(socket.getOutputStream(),
                    true);

            out.println("MOTD:Welcome to the testing phase of this chat!");
            out.println("To view commands simply type /help");

            while (true) {
                String input = in.readLine();
                if (input == null || input.equals(".")) {
                    break;
                }
                out.println(input);
            }
        } catch (IOException e) {
            Chat.serverWindow.append("Error handling client");
        } finally {
            try {
                socket.close();
            } catch (IOException e) {
                Chat.serverWindow
                        .append("Couldn't close a socket, what's going on?");
            }
            Chat.serverWindow.append("Connection with client closed");
        }
    }

}
}

客户端代码:

        package net.valid4life.chat;

import java.awt.Component;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;

public class Chat implements ActionListener {

private static JFrame mainFrame;
private static JPanel contentPane;

private static JTextArea chatWindow;

private static JTextField chatBox;
private static JTextField portBox;

private static JLabel currentStatusL;
private static JLabel portl;
private static JLabel status;

private static JButton connectButton;

private static int port = 1234;
private static String hostIP = "127.0.0.1";

public static final int NOT_STARTED = 0;
public static final int WAITING_FOR_SERVER = 1;
public static final int CONNECTED = 2;
private static int currentStatus = NOT_STARTED;

public static boolean serverStarted = false;
private static JTextField IPField;
private static JLabel IPL;

private static BufferedReader in;
private static PrintWriter out;

public static void initGUI() {

public static void connectToServer() throws Exception {

    port = Integer.parseInt(portBox.getText());
    hostIP = IPField.getText();

    Socket socket = new Socket("127.0.0.1", 1234);

    in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    out = new PrintWriter(socket.getOutputStream(), true);

    for (int i = 0; i < 3; i++) {
        chatWindow.append(in.readLine() + "\n");
    }
    // connectButton.setEnabled(false);
}


public static void main(String[] args) throws Exception {
    initGUI();
    connectToServer();
}

public void actionPerformed(ActionEvent e) {
    if ("start".equals(e.getActionCommand())) {
        try {
            connectToServer();
        } catch (Exception e1) {
            e1.printStackTrace();
        }
    } else {System.out.println("ASDASD");}

    }


public static String changeStatus(int newStatus) {
    String newStatusText;
    switch (newStatus) {
    case 0:
        newStatusText = "Server not started.";
        break;
    case 1:
        newStatusText = "Waiting for client.";
        break;
    case 2:
        newStatusText = "Connected to client.";
        break;
    default:
        newStatusText = "Broken";
    }

    currentStatus = newStatus;
    return newStatusText;
}

}

预先感谢您的帮助!

Answer 1

您的服务器代码运行良好，但当您调用 connectToServer 时，您的客户端会阻塞事件调度线程。

事件调度线程负责处理重绘请求和新输入事件等。如果您出于任何原因阻塞此线程，则事件调度线程将无法处理任何新事件...

所有阻塞或长时间运行的任务都应该在事件调度线程的上下文之外执行。

看看Concurrency in Swing了解更多详情