为什么右键单击在java应用程序上不起作用？

Question

我制作了一个基于 Java Swing 的应用程序。
在我的应用程序中，如果我单击 JFrame 或任何其他内容上的任意位置，那么我的右键单击不起作用？
我没有设置类似的东西..那么为什么不工作？

基本上我的键盘不工作然后我尝试使用鼠标复制 - 粘贴数据然后，我开始知道......我的右键单击是不适用于我的应用程序的任何区域...

Answer 1

您的右键单击工作得很好 - 在 Swing 中，无法获得您在其他应用程序中习惯的上下文菜单是正常的。例如，如果您希望右键单击时打开一个带有剪切/复制/粘贴操作的弹出菜单 - 您必须自己实现它。我在我的应用程序中使用类似的东西：

public class ContextMenuMouseListener extends MouseAdapter {
    private JPopupMenu popup = new JPopupMenu();

    private Action cutAction;
    private Action copyAction;
    private Action pasteAction;
    private Action undoAction;
    private Action selectAllAction;

    private JTextComponent textComponent;
    private String savedString = "";
    private Actions lastActionSelected;

    private enum Actions { UNDO, CUT, COPY, PASTE, SELECT_ALL };

    public ContextMenuMouseListener() {
        undoAction = new AbstractAction("Undo") {

            @Override
            public void actionPerformed(ActionEvent ae) {
                    textComponent.setText("");
                    textComponent.replaceSelection(savedString);

                    lastActionSelected = Actions.UNDO;
            }
        };

        popup.add(undoAction);
        popup.addSeparator();

        cutAction = new AbstractAction("Cut") {

            @Override
            public void actionPerformed(ActionEvent ae) {
                lastActionSelected = Actions.CUT;
                savedString = textComponent.getText();
                textComponent.cut();
            }
        };

        popup.add(cutAction);

        copyAction = new AbstractAction("Copy") {

            @Override
            public void actionPerformed(ActionEvent ae) {
                lastActionSelected = Actions.COPY;
                textComponent.copy();
            }
        };

        popup.add(copyAction);

        pasteAction = new AbstractAction("Paste") {

            @Override
            public void actionPerformed(ActionEvent ae) {
                lastActionSelected = Actions.PASTE;
                savedString = textComponent.getText();
                textComponent.paste();
            }
        };

        popup.add(pasteAction);
        popup.addSeparator();

        selectAllAction = new AbstractAction("Select All") {

            @Override
            public void actionPerformed(ActionEvent ae) {
                lastActionSelected = Actions.SELECT_ALL;
                textComponent.selectAll();
            }
        };

        popup.add(selectAllAction);
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        if (e.getModifiers() == InputEvent.BUTTON3_MASK) {
            if (!(e.getSource() instanceof JTextComponent)) {
                return;
            }

            textComponent = (JTextComponent) e.getSource();
            textComponent.requestFocus();

            boolean enabled = textComponent.isEnabled();
            boolean editable = textComponent.isEditable();
            boolean nonempty = !(textComponent.getText() == null || textComponent.getText().equals(""));
            boolean marked = textComponent.getSelectedText() != null;

            boolean pasteAvailable = Toolkit.getDefaultToolkit().getSystemClipboard().getContents(null).isDataFlavorSupported(DataFlavor.stringFlavor);

            undoAction.setEnabled(enabled && editable && (lastActionSelected == Actions.CUT || lastActionSelected == Actions.PASTE));
            cutAction.setEnabled(enabled && editable && marked);
            copyAction.setEnabled(enabled && marked);
            pasteAction.setEnabled(enabled && editable && pasteAvailable);
            selectAllAction.setEnabled(enabled && nonempty);

            int nx = e.getX();

            if (nx > 500) {
                nx = nx - popup.getSize().width;
            }

            popup.show(e.getComponent(), nx, e.getY() - popup.getSize().height);
        }
    }
}

最后，您应该将此侦听器附加到您希望右键单击时有上下文菜单的任何文本组件。

Answer 2

您的意思是您没有上下文菜单吗？在 Swing 应用程序中，您必须自己添加上下文菜单。
有关详细信息，请参阅本文。

Answer 3

class Popup extends JPopupMenu
{
    final static long serialVersionUID = 0;

    Clipboard clipboard;

    UndoManager undoManager;

    JMenuItem jmenuItem_undo;
    JMenuItem jmenuItem_cut;
    JMenuItem jmenuItem_copy;
    JMenuItem jmenuItem_paste;
    JMenuItem jmenuItem_delete;
    JMenuItem jmenuItem_selectAll;

    JTextComponent jtextComponent;

    public Popup()
    {
        undoManager = new UndoManager();

        clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();

        jmenuItem_undo = new JMenuItem("undo");
        jmenuItem_undo.setEnabled(false);
        jmenuItem_undo.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent event)
            {
                undoManager.undo();
            }
        });

        this.add(jmenuItem_undo);

        this.add(new JSeparator());

        jmenuItem_cut = new JMenuItem("cut");
        jmenuItem_cut.setEnabled(false);
        jmenuItem_cut.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent event)
            {
                jtextComponent.cut();
            }
        });

        this.add(jmenuItem_cut);

        jmenuItem_copy = new JMenuItem("copy");
        jmenuItem_copy.setEnabled(false);
        jmenuItem_copy.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent event)
            {
                jtextComponent.copy();
            }
        });

        this.add(jmenuItem_copy);

        jmenuItem_paste = new JMenuItem("paste");
        jmenuItem_paste.setEnabled(false);
        jmenuItem_paste.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent event)
            {
                jtextComponent.paste();
            }
        });

        this.add(jmenuItem_paste);

        jmenuItem_delete = new JMenuItem("delete");
        jmenuItem_delete.setEnabled(false);
        jmenuItem_delete.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent event)
            {
                jtextComponent.replaceSelection("");
            }
        });

        this.add(jmenuItem_delete);

        this.add(new JSeparator());

        jmenuItem_selectAll = new JMenuItem("select all");
        jmenuItem_selectAll.setEnabled(false);
        jmenuItem_selectAll.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent event)
            {
                jtextComponent.selectAll();
            }
        });

        this.add(jmenuItem_selectAll);
    }

    public void add(JTextComponent jtextComponent)
    {
        jtextComponent.addMouseListener(new MouseAdapter()
        {
            public void mouseReleased(MouseEvent event)
            {
                if (event.getButton() == 3)
                {
                    processClick(event);
                }
            }
        });

        jtextComponent.getDocument().addUndoableEditListener(new UndoableEditListener()
        {
            public void undoableEditHappened(UndoableEditEvent event)
            {
                undoManager.addEdit(event.getEdit());
            }
        });
    }

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

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

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

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

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

        try
        {
            if (clipboard.getData(DataFlavor.stringFlavor) != null)
            {
                enablePaste = true;
            }
        }
        catch (Exception exception)
        {
            System.out.println(exception);
        }

        jmenuItem_undo.setEnabled(enableUndo);
        jmenuItem_cut.setEnabled(enableCut);
        jmenuItem_copy.setEnabled(enableCopy);
        jmenuItem_paste.setEnabled(enablePaste);
        jmenuItem_delete.setEnabled(enableDelete);
        jmenuItem_selectAll.setEnabled(enableSelectAll);

        this.show(jtextComponent,event.getX(),event.getY());
    }
}

并实施它，

Popup popup = new Popup();

JTextArea jtextArea;
JTextField jtextField;

popup.add(jtextArea);
popup.add(jtextField);