有没有办法让一个类中的JTextArea响应另一个类的JButton点击

Question

我需要让ChatPanel类中的JTextField响应Toolbar类中的JButton点击。如果我的程序变得很大，有什么方法可以做到这一点吗？我试着用Action对象做这件事，但我不确定我需要用这个对象做什么。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 "hellon" 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，任何关于我可以改进的地方/我做错了什么的反馈都将受到赞赏。

Answer 1

你的问题实际上有点大，但有了一些聪明的想法，很容易克服。。。

从本质上讲，您需要通过某种方式从Toolbar与ChatPanel进行通信。有很多方法可以实现这一点，但如果你想要灵活性，那么你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"会为某些内容添加文本

从这里开始，我们需要一些能够将行动和想要更新的内容联系起来的东西。

让我们从一个简单的合同开始

public interface Outlet {
    public void say(String text);
}

所有这些都表明，这个接口的实现可以接受一些文本。

接下来，我们需要一些方法来设置操作发生时的文本，假设您想要几个不同的操作，比如。。。

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该发送到的Outlet和要发送的文本

现在，为了让生活更轻松，你可以设置一系列常见的"单词"动作，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，您需要某种方法将这些操作应用于Toolbar。。。

public class Toolbar extends JPanel {
    public void addAction(Action action) {
        add(new JButton(action));
    }
}

简单地添加一个负责创建JButton并对其应用操作的addAction方法似乎是一个简单的解决方案。

最后，我们需要更新ChatPanel以实现Outlet interface

public class ChatPanel extends JPanel implements Outlet {
    //...
    @Override
    public void say(String text) {
        chatArea.append(text + NEWLINE);
    }
}

现在，你只需要把它们绑在一起。。。

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

这展示了一个通常被称为"代码到接口(而不是实现("的原则，它将代码解耦，从而允许您在不影响代码其余部分的情况下更改底层实现。它还保护您的代码免受不必要的交互，因为操作只能调用Outlet接口的say方法；(

最后，一个可运行的例子。。。

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);
        }
    }
}