如何在Java Swing中创建右键单击上下文菜单？

Question

我正在创建一个右键单击上下文菜单，方法是在右键单击时实例化一个新的JMenu并将其位置设置为鼠标的位置...有更好的方法吗？

Answer 1

您可能在菜单上手动拨打setVisible(true)。这可能会导致菜单中出现一些讨厌的错误行为。

show(Component, int x, int x)方法处理您需要发生的所有事情，（在鼠标悬停时突出显示内容并在必要时关闭弹出窗口），使用setVisible(true)只显示菜单而不添加任何其他行为。< / p>

要制作右键单击弹出菜单，只需创建JPopupMenu。

class PopUpDemo extends JPopupMenu {
    JMenuItem anItem;
    public PopUpDemo() {
        anItem = new JMenuItem("Click Me!");
        add(anItem);
    }
}

然后，您需要做的就是将自定义MouseListener添加到您希望弹出菜单的组件中。

class PopClickListener extends MouseAdapter {
    public void mousePressed(MouseEvent e) {
        if (e.isPopupTrigger())
            doPop(e);
    }

    public void mouseReleased(MouseEvent e) {
        if (e.isPopupTrigger())
            doPop(e);
    }

    private void doPop(MouseEvent e) {
        PopUpDemo menu = new PopUpDemo();
        menu.show(e.getComponent(), e.getX(), e.getY());
    }
}

// Then on your component(s)
component.addMouseListener(new PopClickListener());

当然，教程有slightly more in-depth解释。

注意：如果您发现弹出式菜单与用户点击的位置相差不远，请尝试使用e.getXOnScreen()和e.getYOnScreen()方法获取x和y坐标

Answer 2

这个问题有点陈旧 - 答案也是如此（以及教程）

用于在Swing中设置popupMenu的当前api是

myComponent.setComponentPopupMenu(myPopupMenu);

这种方式将自动显示鼠标和键盘触发器（后者取决于LAF）。此外，它支持在容器的子项中重复使用相同的弹出窗口。要启用该功能：

myChild.setInheritsPopupMenu(true);

Answer 3

Bringing Up a Popup Menu文章How to Use Menus中有The Java Tutorials部分，其中介绍了如何使用JPopupMenu课程。

本教程中的示例代码显示了如何将MouseListener添加到应显示弹出菜单的组件，并相应地显示菜单。

（您描述的方法与教程提供在组件上显示弹出菜单的方式非常相似。）

Answer 4

以下代码实现了Windows中已知的默认上下文菜单，包括复制，剪切，粘贴，全选，撤消和重做功能。它也适用于Linux和Mac OS X：

import javax.swing.*;
import javax.swing.text.JTextComponent;
import javax.swing.undo.UndoManager;
import java.awt.*;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.DataFlavor;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

public class DefaultContextMenu extends JPopupMenu
{
    private Clipboard clipboard;

    private UndoManager undoManager;

    private JMenuItem undo;
    private JMenuItem redo;
    private JMenuItem cut;
    private JMenuItem copy;
    private JMenuItem paste;
    private JMenuItem delete;
    private JMenuItem selectAll;

    private JTextComponent textComponent;

    public DefaultContextMenu()
    {
        undoManager = new UndoManager();
        clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();

        addPopupMenuItems();
    }

    private void addPopupMenuItems()
    {
        undo = new JMenuItem("Undo");
        undo.setEnabled(false);
        undo.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Z, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()));
        undo.addActionListener(event -> undoManager.undo());
        add(undo);

        redo = new JMenuItem("Redo");
        redo.setEnabled(false);
        redo.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Y, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()));
        redo.addActionListener(event -> undoManager.redo());
        add(redo);

        add(new JSeparator());

        cut = new JMenuItem("Cut");
        cut.setEnabled(false);
        cut.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_X, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()));
        cut.addActionListener(event -> textComponent.cut());
        add(cut);

        copy = new JMenuItem("Copy");
        copy.setEnabled(false);
        copy.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_C, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()));
        copy.addActionListener(event -> textComponent.copy());
        add(copy);

        paste = new JMenuItem("Paste");
        paste.setEnabled(false);
        paste.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_V, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()));
        paste.addActionListener(event -> textComponent.paste());
        add(paste);

        delete = new JMenuItem("Delete");
        delete.setEnabled(false);
        delete.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_DELETE, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()));
        delete.addActionListener(event -> textComponent.replaceSelection(""));
        add(delete);

        add(new JSeparator());

        selectAll = new JMenuItem("Select All");
        selectAll.setEnabled(false);
        selectAll.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_A, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()));
        selectAll.addActionListener(event -> textComponent.selectAll());
        add(selectAll);
    }

    private void addTo(JTextComponent textComponent)
    {
        textComponent.addKeyListener(new KeyAdapter()
        {
            @Override
            public void keyPressed(KeyEvent pressedEvent)
            {
                if ((pressedEvent.getKeyCode() == KeyEvent.VK_Z)
                        && ((pressedEvent.getModifiersEx() & Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()) != 0))
                {
                    if (undoManager.canUndo())
                    {
                        undoManager.undo();
                    }
                }

                if ((pressedEvent.getKeyCode() == KeyEvent.VK_Y)
                        && ((pressedEvent.getModifiersEx() & Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()) != 0))
                {
                    if (undoManager.canRedo())
                    {
                        undoManager.redo();
                    }
                }
            }
        });

        textComponent.addMouseListener(new MouseAdapter()
        {
            @Override
            public void mousePressed(MouseEvent releasedEvent)
            {
                handleContextMenu(releasedEvent);
            }

            @Override
            public void mouseReleased(MouseEvent releasedEvent)
            {
                handleContextMenu(releasedEvent);
            }
        });

        textComponent.getDocument().addUndoableEditListener(event -> undoManager.addEdit(event.getEdit()));
    }

    private void handleContextMenu(MouseEvent releasedEvent)
    {
        if (releasedEvent.getButton() == MouseEvent.BUTTON3)
        {
            processClick(releasedEvent);
        }
    }

    private void processClick(MouseEvent event)
    {
        textComponent = (JTextComponent) event.getSource();
        textComponent.requestFocus();

        boolean enableUndo = undoManager.canUndo();
        boolean enableRedo = undoManager.canRedo();
        boolean enableCut = false;
        boolean enableCopy = false;
        boolean enablePaste = false;
        boolean enableDelete = false;
        boolean enableSelectAll = false;

        String selectedText = textComponent.getSelectedText();
        String text = textComponent.getText();

        if (text != null)
        {
            if (text.length() > 0)
            {
                enableSelectAll = true;
            }
        }

        if (selectedText != null)
        {
            if (selectedText.length() > 0)
            {
                enableCut = true;
                enableCopy = true;
                enableDelete = true;
            }
        }

        if (clipboard.isDataFlavorAvailable(DataFlavor.stringFlavor) && textComponent.isEnabled())
        {
            enablePaste = true;
        }

        undo.setEnabled(enableUndo);
        redo.setEnabled(enableRedo);
        cut.setEnabled(enableCut);
        copy.setEnabled(enableCopy);
        paste.setEnabled(enablePaste);
        delete.setEnabled(enableDelete);
        selectAll.setEnabled(enableSelectAll);

        // Shows the popup menu
        show(textComponent, event.getX(), event.getY());
    }

    public static void addDefaultContextMenu(JTextComponent component)
    {
        DefaultContextMenu defaultContextMenu = new DefaultContextMenu();
        defaultContextMenu.addTo(component);
    }
}

用法：

JTextArea textArea = new JTextArea();
DefaultContextMenu.addDefaultContextMenu(textArea);

现在textArea在右键单击时会有一个上下文菜单。

Answer 5

我将更正@BullyWillPlaza建议的方法的用法。原因是当我尝试将textArea添加到仅仅contextMenu时它不可见，如果我将它添加到contextMenu和某些面板它会发生：如果我尝试切换到设计编辑器，则不同的父双重关联。

TexetObjcet.addMouseListener(new MouseAdapter() {
        @Override
        public void mouseClicked(MouseEvent e) {
            if (SwingUtilities.isRightMouseButton(e)){
                contextmenu.add(TexetObjcet);
                contextmenu.show(TexetObjcet, 0, 0);
            }
        }
    }); 

为你需要弹出的文本对象制作这样的鼠标监听器。这将是你右键单击文本对象然后添加该弹出窗口并显示它。这样您就不会遇到该错误。 @BullyWillPlaza所做的解决方案非常好，在您的程序中实现丰富和快速，因此您应该尝试它，我们看看您喜欢它。