ContextMenuMouseListener.java 文件源码

@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);
    }
}