支持复制选项

Question

我正在 NetBeans 中编写 Java Swing 计算器。我有 JFrame、计算器按钮和名为 display 的 JTextField。我需要支持复制（以及 CTRL+C）选项。有谁知道如何做到这一点？

Answer 1

如果您想为剪切/复制/粘贴添加右键菜单，您可以使用组件已有的剪切/复制/粘贴操作，尽管我更喜欢重命名它们以使它们更易于阅读，因为“剪切”比“剪切到剪贴板”更容易阅读。

例如，如果您调用此方法并传入任何文本组件，它应该添加一个右键弹出菜单用于剪切-复制-粘贴：

// allows default cut copy paste popup menu actions
private void addCutCopyPastePopUp(JTextComponent textComponent) {
   ActionMap am = textComponent.getActionMap();
   Action paste = am.get("paste-from-clipboard");
   Action copy = am.get("copy-to-clipboard");
   Action cut = am.get("cut-to-clipboard");

   cut.putValue(Action.NAME, "Cut");
   copy.putValue(Action.NAME, "Copy");
   paste.putValue(Action.NAME, "Paste");

   JPopupMenu popup = new JPopupMenu("My Popup");
   textComponent.setComponentPopupMenu(popup);
   popup.add(new JMenuItem(cut));
   popup.add(new JMenuItem(copy));
   popup.add(new JMenuItem(paste));
}

例如：

import java.awt.BorderLayout;
import javax.swing.*;
import javax.swing.text.JTextComponent;

public class AddCopyAndPaste extends JPanel {
    private JTextField textField = new JTextField("Four score and seven years ago...");
    private JTextArea textArea = new JTextArea(15, 30);

    public AddCopyAndPaste() {
        addCutCopyPastePopUp(textField);
        addCutCopyPastePopUp(textArea);

        setLayout(new BorderLayout());
        add(textField, BorderLayout.PAGE_START);
        add(new JScrollPane(textArea), BorderLayout.CENTER);
    }

    // allows default cut copy paste popup menu actions
    private void addCutCopyPastePopUp(JTextComponent textComponent) {
       ActionMap am = textComponent.getActionMap();
       Action paste = am.get("paste-from-clipboard");
       Action copy = am.get("copy-to-clipboard");
       Action cut = am.get("cut-to-clipboard");

       cut.putValue(Action.NAME, "Cut");
       copy.putValue(Action.NAME, "Copy");
       paste.putValue(Action.NAME, "Paste");

       JPopupMenu popup = new JPopupMenu("My Popup");
       textComponent.setComponentPopupMenu(popup);
       popup.add(new JMenuItem(cut));
       popup.add(new JMenuItem(copy));
       popup.add(new JMenuItem(paste));
    }

    private static void createAndShowGui() {
        AddCopyAndPaste mainPanel = new AddCopyAndPaste();

        JFrame frame = new JFrame("Add Copy And Paste");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.getContentPane().add(mainPanel);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGui();
            }
        });
    }
}