检测特殊字符的按键答案

【问题标题】：Detecting Key presses for Special Characters检测特殊字符的按键
【发布时间】：2012-11-05 13:52:09
【问题描述】：

当按下具有相同字母/符号的键时，我试图更改按钮的背景颜色，但问题是此代码不适用于符号和空格，我做错了什么，如何解决？

代码如下：

    private String names[]={"`"," 1 "," 2 "," 3 "," 4 "," 5 "," 6 "," 7 "," 8 "," 9 "," 0 "," - "," + ","  Backspace  "
        ,"  Tab  "," Q "," W "," E "," R "," T "," Y "," U "," I "," O "," P "," [ "," ] "," \\ "
        ,"  Caps Lock "," A "," S "," D "," F "," G "," H "," J "," K "," L "," ; "," ' ","  Enter  "
        ,"  Shift  "," Z "," X "," C "," V "," B "," N "," M "," , "," . "," / "," ^ "
        ,"                             "," < "," ! "," > "};


public void keyPressed(KeyEvent event)
    {
        int code= event.getKeyCode();
        String x;

        for(int i=0;i<names.length;i++)
        {

            s=names[i];
            x=s.trim();

            if(x.contentEquals(event.getKeyText(code)) )
            {
                backColor=but[i].getBackground();
                but[i].setBackground(Color.RED);
                break;
            }
        }
    }

    public void keyReleased(KeyEvent event)
    {
        String x;
        int code= event.getKeyCode();

        for(int i=0;i<names.length;i++)
        {
            s=names[i];
            x=s.trim();

            if(x.contentEquals(event.getKeyText(code)))
            {System.out.println("outside");
                but[i].setBackground(backColor);
                break;
            }
        }
    }

问候

【问题讨论】：

标签： java jbutton keylistener

【解决方案1】：

我会查看names 数组并将其与KeyEvent#getKeyText 的结果进行比较

我的小测试程序输出了这个...

[PRESSED ] "Space"
[TYPED   ] "Unknown keyCode: 0x0"
[RELEASED] "Space"
[PRESSED ] "Enter"
[TYPED   ] "Unknown keyCode: 0x0"
[RELEASED] "Enter"

你的names 数组有空间存储为" Space "，这永远不会匹配。

您永远不应依赖来自KeyEvent#getKetText 的结果，因为它没有考虑键盘的当前扩展状态（即，如果按下 shift），这可能会改变键的状态。

例如，如果我输入 [']，我的测试程序将输出 Quote，但如果我输入 [shift+']（应该产生 ["]），它仍然会显示 Quote。甚至没有得到我从 { 和 [ :P

开始

如果你对显示击键文本不感兴趣，你最好依靠虚拟键值

public class PaintMyKeys {

    public static void main(String[] args) {
        new    PaintMyKeys();
    }

    public PaintMyKeys() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new PaintMyKeysPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class PaintMyKeysPane extends JPanel {

        private JLabel label;

        public PaintMyKeysPane() {

            setLayout(new BorderLayout());

            label = new JLabel("Press space to change colors", JLabel.CENTER);
            label.setOpaque(true);

            add(label);

            addKeyListener(new KeyAdapter() {

                protected int random() {
                    return (int)Math.round(Math.random() * 255);
                }

                protected Color randomColor() {

                    int r = random();
                    int g = random();
                    int b = random();
                    int a = random();

                    return new Color(r, g, b, a);

                }

                @Override
                public void keyReleased(KeyEvent e) {
                    if (e.getKeyCode() == KeyEvent.VK_SPACE) {
                        label.setBackground(randomColor());
                        label.setForeground(randomColor());

                    }
                }
            });

            setFocusable(true);
            requestFocusInWindow();        
        }
    }
}

【讨论】：

【解决方案2】：

作为一般规则，getKeyText() 的结果在浏览器中是不统一的，并且与实际上是文本（字母和数字）的键无关。

我认为您应该重新考虑使用 getKeyCode() 的方法。

有用的链接：

This page 可用于测试哪个 keyCode 与钥匙。
This page为你提供了key和key之间的映射代码。

【讨论】：

【解决方案3】：

据我所知，getKeyText() 方法返回的是单词而不是大多数符号（例如，“.”的代码产生“PERIOD”）。不要在名称数组中使用“.”等类似名称，而是使用“PERIOD”和“SPACE”。

Here 是 getKeyText() 方法的代码，它准确显示了哪些字符将返回密钥的名称。

【讨论】：