java - 如何输出到 GUI、暂停，然后输出其他内容(例如使用 SwingWorker)？

Question

我正在用 Java 制作一个简单的基于文本的回合制战斗游戏(作为学习练习，所以我试图理解我所做的一切)，我想模拟对手的回合。这本质上涉及打印出一条消息(例如“轮到敌人了”)，处理敌人的轮到，暂停(使用 Thread.sleep )，然后打印出另一条消息(“例如“轮到你了”)。

我的 GUI 是一个带有 Swing 元素的 JApplet 类，尽管这是因为它易于制作和理解，而不是因为我对使用 Swing 有任何执着。我没有多线程方面的经验，但已经了解到 SwingWorker 在这种情况下很有用(在长时间的后台进程运行时更新 Swing GUI)。这是一个没有实际游戏代码的版本，为了简单起见，所有代码都包含在同一个类中:

public class SimpleGame extends JApplet implements ActionListener {
    private Game game;
    private String inputCommand;
    private JTextArea textOutput;
    private JTextField inputField;
    public void init() {
        textOutput = new JTextArea();
        DefaultCaret caret = (DefaultCaret) textOutput.getCaret();
        caret.setUpdatePolicy(DefaultCaret.ALWAYS_UPDATE);
        textOutput.setEditable(false);
        Container window = getContentPane();
        window.setLayout(new BorderLayout());
        window.add(textOutput, BorderLayout.CENTER);
        JButton submitButton = new JButton("Submit");
        submitButton.addActionListener(this);
        inputField = new JTextField(20);
        inputField.addActionListener(this);
        JPanel inputPanel = new JPanel();
        inputPanel.add(inputField);
        inputPanel.add(submitButton);
        window.add(inputPanel, BorderLayout.SOUTH);
        inputField.requestFocusInWindow();
        game = new Game();
    }
    public class GuiUpdater extends SwingWorker<Boolean, String> {
        private String command;
        public GuiUpdater(String inputCommand) {
            super();
            command = inputCommand;
        }
        public void publish(String chunk) {
            super.publish(chunk);
        }
        protected Boolean doInBackground() throws Exception {
            Output.setWorker(this);
            boolean successfulCommand = game.performCommand(command);
            return successfulCommand;
        }
        protected void process(List<String> chunks) {
            for (String chunk : chunks) {
                textOutput.append(chunk);
            }
        }
    }
    public void actionPerformed(ActionEvent event) {
        if (game.isItYourTurn()) {
            inputCommand = inputField.getText();
            if (inputCommand.length() != 0) {
                GuiUpdater worker = new GuiUpdater(inputCommand);
                worker.execute();
                boolean successfulCommand;
                try {
                    successfulCommand = worker.get();
                } catch (InterruptedException | ExecutionException e) {
                    successfulCommand = false;
                }
                if (!successfulCommand) {
                    textOutput.append("Invalid command.\n");
                }
                inputField.setText("");
            }
        } else {
            textOutput.append("\nWait for your turn!\n");
        }
    }
    private static class Output {
        private static GuiUpdater worker;
        static void setWorker(GuiUpdater newWorker) {
            worker = newWorker;
        }
        static void update(String updateText) {
            worker.publish(updateText);
        }
    }
    private class Game {
        private boolean yourTurn;
        public Game() {
            yourTurn = true;
        }
        public boolean isItYourTurn() {
            return yourTurn;
        }
        public boolean performCommand(String inputString) throws InterruptedException {
            yourTurn = false;
            // perform player action
            Output.update("\nEnemy turn");
            Thread.sleep(1000);
            // perform enemy action
            Output.update("\nYour turn");
            yourTurn = true;
            return true;
        }
    }
}

不幸的是，不是输出一行，等待一秒钟，然后输出第二行，而是在所有 sleep 完成后将所有行输出到 Swing GUI。如果我将 Output.update("text") 替换为 System.out.println("text") 那么计时将按预期进行，但显然我没有我的游戏只想依赖控制台输出。

如果有人对我做错了什么有解释，或者有在输出之间暂停的替代方法，我将不胜感激。干杯!

Answer 1

您对worker.get() 的调用会阻塞swing-applet 线程，直到worker 完成为止。您需要将对结果的处理移至 SwingWorker did() 方法中，该方法在 doInBackground() 方法完成之前不会执行。这部分代码应该如下所示:

public class GuiUpdater extends SwingWorker<Boolean, String> {
    private String command;

    public GuiUpdater(String inputCommand) {
        super();
        command = inputCommand;
    }

    public void publish(String chunk) {
        super.publish(chunk);
    }

    @Override
    protected Boolean doInBackground() throws Exception {
        Output.setWorker(this);
        boolean successfulCommand = game.performCommand(command);
        return successfulCommand;
    }

    @Override
    protected void process(List<String> chunks) {
        for (String chunk : chunks) {
            textOutput.append(chunk);
        }
    }

    @Override
    protected void done() {
        boolean successfulCommand;
        try {
            successfulCommand = get();
        } catch (InterruptedException | ExecutionException e) {
            successfulCommand = false;
        }
        if (!successfulCommand) {
            textOutput.append("Invalid command.\n");
        }
        inputField.setText("");
    }
}

@Override
public void actionPerformed(ActionEvent event) {
    if (game.isItYourTurn()) {
        inputCommand = inputField.getText();
        if (inputCommand.length() != 0) {
            GuiUpdater worker = new GuiUpdater(inputCommand);
            worker.execute();
        }
    } else {
        textOutput.append("\nWait for your turn!\n");
    }
}