java - 有没有办法让一个类中的 JTextArea 响应另一个类中的 JButton 单击？

Question

我需要使 ChatPanel 类中的 JTextField 响应 Toolbar 类中的 JButton 单击。如果我的程序变大，有什么方法可以很好地扩展吗？我尝试使用 Action 对象执行此操作，但我不确定需要对该对象执行什么操作。这是我的代码:

public class Toolbar extends JPanel {

private JButton helloButton;

public Toolbar() {
    setLayout(new FlowLayout());

    helloButton = new JButton(new HelloAction("Hello", null));

    add(helloButton);

}


class HelloAction extends AbstractAction {

    public HelloAction(String text, ImageIcon icon) {
        super(text, icon);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        //want to print "hello\n" in the JTextArea in ChatPanel
    }
}

}

public class ChatPanel extends JPanel {

private JLabel nameLabel;
private JTextField chatField;
private JTextArea chatArea;
private GridBagConstraints gc;

private static final String NEWLINE = "\n";

public ChatPanel() {
    super(new GridBagLayout());

    //chatArea
    chatArea = new JTextArea(8, 30);
    chatArea.setEditable(false);
    JScrollPane scrollPane = new JScrollPane(chatArea);
    gc = new GridBagConstraints();
    gc.gridx = 0;
    gc.gridy = 0;
    add(scrollPane, gc);

    //nameLabel
    nameLabel = new JLabel("Name: ");
    gc = new GridBagConstraints();
    gc.gridx = 0;
    gc.gridy = 2;
    gc.anchor = GridBagConstraints.LINE_START;
    gc.weightx = 0.0;
    add(nameLabel, gc);

    //chatField
    chatField = new JTextField(25);
    chatField.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            String message = chatField.getText() + NEWLINE;
            chatArea.append(message);
            chatField.setText("");
        }

    });
    gc = new GridBagConstraints();
    gc.gridx = 0;
    gc.gridy = 2;
    gc.anchor = GridBagConstraints.LINE_END;
    gc.weightx = 0.0;
    add(chatField, gc);



}

}

public class MainFrame {

private static int width = 800;
private static int height = (int) (width * (9.0 / 16));

private JFrame mainFrame = new JFrame("Main Frame");

public MainFrame() {
    mainFrame.setPreferredSize(new Dimension(width, height));
    mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    mainFrame.setLayout(new GridBagLayout());
    mainFrame.pack();
    mainFrame.setResizable(false);

    //Toolbar
    Toolbar toolbar = new Toolbar();

    GridBagConstraints gcToolbar = new GridBagConstraints();
    gcToolbar.gridx = 0;
    gcToolbar.gridy = 0;
    mainFrame.add(toolbar);

    //ChatPanel
    ChatPanel chatPanel = new ChatPanel();
    GridBagConstraints gcChatPanel = new GridBagConstraints();
    gcChatPanel.gridx = 0;
    gcChatPanel.gridy = 2;
    gcChatPanel.gridwidth = 2;
    gcChatPanel.weighty = 1.0;
    gcChatPanel.weightx = 1.0;
    gcChatPanel.anchor = GridBagConstraints.LAST_LINE_START;
    mainFrame.add(chatPanel, gcChatPanel);

    mainFrame.setVisible(true);
}   

}

此外，任何有关我可以改进的地方/我做错的地方的反馈都会受到赞赏。

Answer 1

你的问题实际上有点大，但是通过一些巧妙的想法，很容易克服......

本质上，您需要某种方式从工具栏与ChatPanel进行通信。有多种方法可以实现这一目标，但如果您想要灵 active ，那么您应该分解需求并专注于每个部分的功能...

1. 工具栏包含“操作”
2. 其中一些“操作”会向某些内容添加文本

从这里开始，我们需要一些东西来桥接操作和想要更新的内容。

让我们从一个简单的契约(Contract)开始

public interface Outlet {

    public void say(String text);

}

这说明的是，该接口(interface)的实现可以接受一些文本。

接下来，我们需要某种方法来在操作发生时设置文本，假设您需要几个不同的操作，例如...

public class OutletAction extends AbstractAction {

    private Outlet outlet;
    private String text;

    public OutletAction(Outlet outlet, String text) {
        this.outlet = outlet;
        this.text = text;
    }

    public Outlet getOutlet() {
        return outlet;
    }

    public String getText() {
        return text;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        getOutlet().say(getText());
    }
}

会让生活更轻松。基本上，这允许您指定文本应发送到的 Outlet 以及要发送的文本

现在，为了让生活更轻松，您可以设置一系列常见的“单词”操作，例如......

public class HelloAction extends OutletAction {

    public HelloAction(Outlet outlet) {
        super(outlet, "Hello");
        putValue(Action.NAME, "Hello");
        //putValue(Action.SMALL_ICON, icon);
    }
}

现在，您需要某种方式将这些操作应用到工具栏...

public class Toolbar extends JPanel {

    public void addAction(Action action) {
        add(new JButton(action));
    }

}

只需添加一个 addAction 方法来负责创建 JButton 并将操作应用于它，这似乎是一个简单的解决方案。

最后，我们需要更新ChatPanel来实现Outlet界面

public class ChatPanel extends JPanel implements Outlet {
    //...

    @Override
    public void say(String text) {
        chatArea.append(text + NEWLINE);
    }

}

现在，您只需将它们全部绑定(bind)在一起......

ChatPanel chatPane = new ChatPanel();

HelloAction action = new HelloAction(chatPane);
Toolbar toolBar = new Toolbar();
toolBar.addAction(action);
//... Add what ever other actions you might like...

这演示了通常称为“代码到接口(interface)(而不是实现)”的原则，它以一种允许您更改底层实现而不影响其余代码的方式解耦代码。它还可以保护您的代码免受不必要的交互，因为操作只能调用 Outlet 接口(interface)的 say 方法;)

最后，一个可运行的示例......

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Main {

    public static void main(String[] args) {
        new Main();
    }

    public Main() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                ChatPanel chatPane = new ChatPanel();

                HelloAction action = new HelloAction(chatPane);
                Toolbar toolBar = new Toolbar();
                toolBar.addAction(action);

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(toolBar, BorderLayout.NORTH);
                frame.add(chatPane);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class Toolbar extends JPanel {

        public void addAction(Action action) {
            add(new JButton(action));
        }

    }

    public class OutletAction extends AbstractAction {

        private Outlet outlet;
        private String text;

        public OutletAction(Outlet outlet, String text) {
            this.outlet = outlet;
            this.text = text;
        }

        public Outlet getOutlet() {
            return outlet;
        }

        public String getText() {
            return text;
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            getOutlet().say(getText());
        }
    }

    public class HelloAction extends OutletAction {

        public HelloAction(Outlet outlet) {
            super(outlet, "Hello");
            putValue(Action.NAME, "Hello");
            //putValue(Action.SMALL_ICON, icon);
        }
    }

    public interface Outlet {

        public void say(String text);

    }

    public class ChatPanel extends JPanel implements Outlet {

        private JLabel nameLabel;
        private JTextField chatField;
        private JTextArea chatArea;
        private GridBagConstraints gc;

        private static final String NEWLINE = "\n";

        public ChatPanel() {
            super(new GridBagLayout());

            //chatArea
            chatArea = new JTextArea(8, 30);
            chatArea.setEditable(false);
            JScrollPane scrollPane = new JScrollPane(chatArea);
            gc = new GridBagConstraints();
            gc.gridx = 0;
            gc.gridy = 0;
            add(scrollPane, gc);

            //nameLabel
            nameLabel = new JLabel("Name: ");
            gc = new GridBagConstraints();
            gc.gridx = 0;
            gc.gridy = 2;
            gc.anchor = GridBagConstraints.LINE_START;
            gc.weightx = 0.0;
            add(nameLabel, gc);

            //chatField
            chatField = new JTextField(25);
            chatField.addActionListener(new ActionListener() {

                @Override
                public void actionPerformed(ActionEvent e) {
                    String message = chatField.getText() + NEWLINE;
                    chatArea.append(message);
                    chatField.setText("");
                }

            });
            gc = new GridBagConstraints();
            gc.gridx = 0;
            gc.gridy = 2;
            gc.anchor = GridBagConstraints.LINE_END;
            gc.weightx = 0.0;
            add(chatField, gc);

        }

        @Override
        public void say(String text) {
            chatArea.append(text + NEWLINE);
        }

    }
}