如何在点击“Enter"时采取行动在“取消"

I have a JFileChooser in a JFrame. I've added an ActionListener to the JFileChooser so that the "Cancel" button works when clicked. I can also tab to the "Cancel" button, but when I then hit the "Enter" key, nothing happens (i.e., the ActionListener isn't called with the event command JFileChooser.CANCEL_SELECTION). What must I do with the JFileChooser so that hitting the "Enter" key when on the "Cancel" button is equivalent to clicking on the "Cancel" button?

这是我看到的(错误)行为的一个简单示例:

Here's a simple example of the (mis)behavior I'm seeing:

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFileChooser;
import javax.swing.JFrame;

public final class TestApp {
    public static void main(final String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                try {
                    final JFileChooser chooser = new JFileChooser();
                    chooser.addActionListener(new ActionListener() {
                        public void actionPerformed(final ActionEvent e) {
                            System.exit(0);
                        }
                    });
                    final JFrame frame = new JFrame();
                    frame.add(chooser);
                    frame.pack();
                    frame.setVisible(true);
                }
                catch (final Throwable t) {
                    t.printStackTrace();
                }
            }
        });
    }
}

要查看(错误)行为，请执行程序，使用 Tab 键选择取消"，然后按Enter"键.该程序不会在我的平台上终止——尽管当我单击取消"按钮时它会终止.

To see the (mis)behavior, execute the program, tab to "Cancel", and then hit the "Enter" key. The program doesn't terminate on my platform -- although it does when I click on the "Cancel" button.

扩展 JFileChooser 和覆盖 cancelSelection() 也不起作用(显然，当在取消"按钮).

Extending JFileChooser and overriding cancelSelection() also doesn't work (apparently, that function isn't called when the "Enter" key is hit while on the "Cancel" button).

(错误)行为发生在我的 Fedora 10 x86_64 系统上，使用 Java 5、6 和 7.

The (mis)behavior occurs on my Fedora 10 x86_64 system with Java 5, 6, and 7.

ADDENDUM:以下将 KeyEventPostProcessor 添加到当前 KeyboardFocusManager 并且似乎可以执行我想要的操作:

ADDENDUM: The following adds a KeyEventPostProcessor to the current KeyboardFocusManager and appears to do what I want:

import java.awt.Component;
import java.awt.KeyEventPostProcessor;
import java.awt.KeyboardFocusManager;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;

import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;

public final class TestApp {
    public static void main(final String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                try {
                    final JFileChooser chooser = new JFileChooser();
                    chooser.addActionListener(new ActionListener() {
                        public void actionPerformed(final ActionEvent e) {
                            System.out.println(e.paramString());
                            System.exit(0);
                        }
                    });
                    final KeyboardFocusManager kfm = KeyboardFocusManager
                            .getCurrentKeyboardFocusManager();
                    kfm.addKeyEventPostProcessor(new KeyEventPostProcessor() {
                        @Override
                        public boolean postProcessKeyEvent(final KeyEvent e) {
                            if (e.getID() == KeyEvent.KEY_RELEASED
                                    && e.getKeyCode() == KeyEvent.VK_ENTER) {
                                final Component comp = e.getComponent();
                                if (chooser.isAncestorOf(comp)) {
                                    if (!(comp instanceof JButton)) {
                                        chooser.approveSelection();
                                    }
                                    else {
                                        final JButton button = (JButton) comp;
                                        if ("Cancel".equals(button.getText())) {
                                            chooser.cancelSelection();
                                        }
                                        else {
                                            chooser.approveSelection();
                                        }
                                    }
                                }
                            }
                            return false;
                        }
                    });
                    final JFrame frame = new JFrame();
                    frame.add(chooser);
                    frame.pack();
                    frame.setVisible(true);
                }
                catch (final Throwable t) {
                    t.printStackTrace();
                }
            }
        });
    }
}

然而，这似乎需要做很多工作，只是为了能够区分按下取消"按钮上的回车键和其他任何地方.

It seems like a lot of work, however, just to be able to distinguish between hitting the enter key on the "Cancel" button versus anywhere else.

你觉得它有什么问题吗?

Do you see any problems with it?

发现的解决方案:将 GUI 外观设置为我的系统 (Linux) 的本机外观和感觉可以满足我的需求，而无需其他任何东西.这是我所不知道的，也是我一直在寻找的.解决方案是有以下

DISCOVERED SOLUTION: Setting the GUI Look and Feel to the native one for my system (Linux) does what I want without the need for anything else. This is what I was ignorant of and what I was looking for. The solution is to have the following

UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

作为 main() 方法的第一个可执行语句.然后可以省去所有焦点侦听器、关键事件处理器等.

as the first executable statement of the main() method. One can then dispense with all focus listeners, key event processors, etc.

我已将 100 分奖励给最有帮助的受访者.

I've awarded the 100 points to the most helpful respondent.

推荐答案

程序不会在我的平台上终止.

The program doesn't terminate on my platform.