java转义出基于文本字段的搜索栏

Question

我有一个带有搜索栏的菜单栏，它是用JTextField实现的，如下所示：

public class Ui_Frame {
    private static JFrame f;
    private static DrawPanel drawPanel;

    public static void main(String[] args) {
        SwingUtilities.invokeLater(Ui_Frame::createAndShowGUI);
    }

    private static void createAndShowGUI() {

        f = new JFrame("Frame");
        drawPanel = new DrawPanel(); //A class that extends JPanel where I draw

        JMenuBar menubar = new JMenuBar();
        JMenu j_menu_data = new JMenu("Data");
        JTextField j_menu_searchfield = new JTextField();
        j_menu_searchfield.setSize(new Dimension(100,20));
        menubar.add(j_menu_data);
        menubar.add(j_menu_searchfield);
        f.setJMenuBar(menubar);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(drawPanel);
        f.pack();
        f.setVisible(true);
   }
}

我有KeyListener个DrawPanel类的KeyListener个，这些工作很好。问题是，当我如上所述将搜索栏JTextField添加到菜单栏时，我写入的所有内容都会写入文本字段，并且我的键侦听器不会触发。我无法“走出”文本字段，因此，如果我在绘图区域内单击，我按下的所有键仍会放入文本字段

我试过getFocus()找DrawPanel但是没有用

如何解决这个问题

编辑： DrawPanel类，因此您拥有运行它所需的所有类：

public class DrawPanel extends JPanel {
    public DrawPanel() {
        addKeyListener(new CustomKeyListener());
        this.setBackground(new Color(220,220,220));
        setBorder(BorderFactory.createLineBorder(Color.black));
        setFocusable(true);
        setVisible(true);
    }

    public Dimension getPreferredSize() {
        return new Dimension(500, 500);
    }

    protected void paintComponent(Graphics g) {
        Graphics2D g2D = (Graphics2D) g;
        super.paintComponent(g2D);
    }

    class CustomKeyListener implements KeyListener {
        @Override
        public void keyTyped(KeyEvent e) {
            if (e.getKeyChar() == KeyEvent.VK_SPACE) {
                System.out.println("Pressed SPACE");
            }

        }
        @Override
        public void keyPressed(KeyEvent e) { }
        @Override
        public void keyReleased(KeyEvent e) { }
    }
}

Answer 1

启动Swing应用程序时，JTextField最初具有键盘焦点。您之所以知道这一点，是因为您看到光标在JTextField内闪烁

用鼠标单击DrawPanel不会将键盘焦点转移到DrawPanel。您知道这一点，因为在DrawPanel内单击鼠标后，光标仍在JTextField内闪烁

您可以通过点击键盘上的TAB键将键盘焦点从JTextField转移到DrawPanel，因为这是默认的焦点遍历键。您知道JTextField不再具有键盘焦点，因为其中没有闪烁的光标

如果您真的希望DrawPanel通过单击其中的鼠标来获得键盘焦点，您可以将MouseListener添加到DrawPanel，如下面的代码所示，该代码本质上是您添加了MouseListener的代码（对于类DrawPanel）

请注意，我没有更改类Ui_Frame

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.BorderFactory;
import javax.swing.JPanel;

public class DrawPanel extends JPanel implements MouseListener {
    public DrawPanel() {
        addKeyListener(new CustomKeyListener());
        addMouseListener(this);
        this.setBackground(new Color(220,220,220));
        setBorder(BorderFactory.createLineBorder(Color.black));
        setFocusable(true);
        setVisible(true);
    }

    public Dimension getPreferredSize() {
        return new Dimension(500, 500);
    }

    protected void paintComponent(Graphics g) {
        Graphics2D g2D = (Graphics2D) g;
        super.paintComponent(g2D);
    }

    class CustomKeyListener implements KeyListener {
        @Override
        public void keyTyped(KeyEvent e) {
            if (e.getKeyChar() == KeyEvent.VK_SPACE) {
                System.out.println("Pressed SPACE");
            }
        }

        @Override
        public void keyPressed(KeyEvent e) { }

        @Override
        public void keyReleased(KeyEvent e) { }
    }

    @Override
    public void mouseClicked(MouseEvent mouseEvent) {
        System.out.println(this.requestFocusInWindow());
    }

    @Override
    public void mousePressed(MouseEvent mouseEvent) {
    }

    @Override
    public void mouseReleased(MouseEvent mouseEvent) {
    }

    @Override
    public void mouseEntered(MouseEvent mouseEvent) {
    }

    @Override
    public void mouseExited(MouseEvent mouseEvent) {
    }
}

请注意，如果方法requestFocusInWindow()成功，它将返回true