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Java Swing JLayeredPane未显示CardLayout卡和背景图像

awt jpanel swing java

fullstacknoob · 技术社区 · 3 年前

我正在为一个小项目使用Java17。我正在用AWT做布局 CardLayout 以及Swing的图形组件。

我想更改我当前的活动 JPanel 在里面 Window.java 每当我点击其中一个 JMenuBarItem 在我的里面 Navbar.java 类,但显示我的背景图像 BackgroundImage 一直使用 JLayeredPane .

Window.java:

public class Window extends JFrame {
JPanel cards;
JLayeredPane layeredPane;

JPanel openPokÃ©dex = new OpenPokÃ©dexPanel();

public Window() {
addWindowListener(new WindowAdapter() {
    public void windowClosing (WindowEvent e) {
    dispose();
    }
});

this.setSize(800, 600);

layeredPane = new JLayeredPane();
this.setContentPane(layeredPane);

BackgroundImage background = new BackgroundImage();
layeredPane.add(background, Integer.valueOf(0));

cards = new JPanel(new CardLayout());
layeredPane.add(cards, Integer.valueOf(1));

cards.add(openPokÃ©dex, "openPokedex");

Navbar bar = new Navbar(cards, this);
this.setJMenuBar(bar);

this.setVisible(true);
}

public void switchPanel(String panelName) {
    CardLayout cardLayout = (CardLayout) cards.getLayout();
    cardLayout.show(cards, panelName);
    System.out.println(panelName);
}
}

Navbar.java:

public class Navbar extends JMenuBar{
JPanel cards;
Window window;

public Navbar(JPanel cards, Window window) {
this.cards = cards;
this.window = window;

JMenu pokedex = new JMenu("PokÃ©dex");
JMenuItem openPokedex = new JMenuItem("Open");
pokedex.add(openPokedex);

this.add(pokedex);

// Events
openPokedex.addActionListener(e -> window.switchPanel("openPokedex"));
}
}

OpenPokdexPanel.java:

public class OpenPokÃ©dexPanel extends JPanel {

OpenPokÃ©dexPanel() {
// tried doing transparent background but made no difference
//this.setOpaque(false);
//this.setBackground(new Color(255, 255, 255, 0));

// pretty much irrelevant. just to see if the panel is actually there
JButton pokÃ©monButton = new JButton("PokÃ©mon");
this.add(pokÃ©monButton);
}
}

背景图片.java:

public class BackgroundImage extends JComponent {
BufferedImage image = null;

public BackgroundImage() {
File bgimage = null;

File directory = new File("src/bin/");

if (directory.isDirectory()) {
    File[] files = directory.listFiles();
    
    if (files != null && files.length > 0) {
    Random rng = new Random();
    File randomFile = files[rng.nextInt(files.length)];
    bgimage = randomFile;
    
    } else {
    System.out.println("No images!");
    }
} else {
    System.out.println("Not a directory!");
}

try {
    image = ImageIO.read(bgimage);
} catch (IOException e) {
    e.printStackTrace();
}
}

@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (image != null) {
    g.drawImage(image, 0, 0, getWidth(), getHeight(), this);
}
}
}

在尝试组合之前 BackgroudImage 与 卡片布局管理器 ,背景图像运行良好,但 面板 s没有出现,因为它们显然是在我的背景图像后面产生的。我想有一个永久的背景 面板 在顶部显示内容。目前,启动程序时只显示白色屏幕

编辑1

我修改了 OpenPokÃ©dexPanel JPanel类:

public class OpenPokÃ©dexPanel extends JPanel {

OpenPokÃ©dexPanel() {

this.setOpaque(false); // added this again
//this.setBackground(new Color(255, 255, 255, 0));

JButton pokÃ©monButton = new JButton("PokÃ©mon");
this.add(pokÃ©monButton);
}
}

我修改了主 Window 班我删除了 J分层窗格 并按照@camicker的建议添加了以下代码:

BackgroundImage background = new BackgroundImage();
this.setLayout(new BorderLayout());
this.setContentPane(background);

cards = new JPanel(new CardLayout());
cards.setOpaque(false);
background.add(cards);

cards.add(openPokÃ©dex, "openPokedex");

背景图像显示,但 面板 卡片 openPokÃ©dex 不会在点击时也显示出来。

2 回复 | 直到 3 年前

camickr 3 年前

Swing具有父/子关系。你会有这样的结构:

框架
- 背景图像(使用BorderLayout)作为内容窗格
  - 非不透明面板(使用CardLayout)
    - 非不透明面板
    - 非不透明面板

基本解决方案是:

JPanel background = new BackgroundImage();
background.setBackground( Color.YELLOW );
background.setLayout( new BorderLayout() );
frame.setContentPane( background );

JPanel cards = new JPanel( new CardLayout() );
cards.setOpaque( false );
background.add( cards );

JPanel card1 = new JPanel();
card1.add( new JLabel("Label for first card") );
card1.setOpaque( false );
cards.add(card1, "card1");

JPanel card2 = new JPanel();
card2.add( new JLabel("Label for second card") );
card2.setOpaque( false );
cards.add(card2, "card2");

因此,首先让上面的代码发挥作用,这样你就可以看到你的面板和其中一张卡片的背景色。如果你有问题,那么你可以发布你的代码,准确地显示你所做的事情。一旦成功,就可以用自定义组件替换基本组件。如果它停止工作,你就会知道你刚刚改变了什么。

MadProgrammer 3 年前

如果你想使用 JLayeredPane 这样,您将需要对其应用合适的布局管理器,例如。。。

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

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

    public Main() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new MainPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public interface Navigatable {
        enum View {
            MENU, CONTENT;
        }
        public void show(View view);
    }

    public class MainPane extends JPanel implements Navigatable {

        private JLayeredPane layeredPane;

        private JPanel contentPane;
        private CardLayout cardLayout;

        private MenuPane menuPane;

        public MainPane() {
            setLayout(new BorderLayout());

            layeredPane = new JLayeredPane();
            add(layeredPane);

            layeredPane.setLayout(new GridBagLayout());

            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridx = 0;
            gbc.gridy = 0;
            gbc.weightx = 1;
            gbc.weighty = 1;
            gbc.fill = GridBagConstraints.BOTH;

            BackgroundPane backgroundPane = new BackgroundPane();
            layeredPane.add(backgroundPane, gbc);
            layeredPane.setLayer(backgroundPane, Integer.valueOf(0));

            cardLayout = new CardLayout();
            contentPane = new JPanel(cardLayout);
            contentPane.setOpaque(false);

            layeredPane.add(contentPane, gbc);
            layeredPane.setLayer(contentPane, Integer.valueOf(1));

            contentPane.add(new MenuPane(this), Navigatable.View.MENU.name());
            JLabel label = new JLabel("This is the content");
            label.setHorizontalAlignment(JLabel.CENTER);
            contentPane.add(label, Navigatable.View.CONTENT.name());
        }

        @Override
        public void show(View view) {
            cardLayout.show(contentPane, view.name());
        }
    }

    public class MenuPane extends JPanel {
        public MenuPane(Navigatable navigatable) {
            setOpaque(false);
            setLayout(new GridBagLayout());
            setBorder(new EmptyBorder(32, 32, 32, 32));

            JButton btn = new JButton("Show me the content");
            add(btn);

            btn.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    navigatable.show(Navigatable.View.CONTENT);
                }
            });
        }       
    }

    public class BackgroundPane extends JPanel {

        private BufferedImage bgImage;

        public BackgroundPane() {
            try {
                bgImage = ImageIO.read(getClass().getResource("/images/Mando01-50.png"));
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }

        @Override
        public Dimension getPreferredSize() {
            if (bgImage != null) {
                return new Dimension(bgImage.getWidth(), bgImage.getHeight());
            }
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            if (bgImage == null) {
                return;
            }
            int x = (getWidth() - bgImage.getWidth()) / 2;
            int y = (getHeight() - bgImage.getHeight()) / 2;
            g.drawImage(bgImage, x, y, this);
        }
    }
}

但是,一个通常更好的解决方案可能是直接使用背景窗格,例如。。。

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

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

    public Main() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new MainPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public interface Navigatable {
        enum View {
            MENU, CONTENT;
        }
        public void show(View view);
    }

    public class MainPane extends JPanel implements Navigatable {

        private BackgroundPane backgroundPane;
        private CardLayout cardLayout;

        private MenuPane menuPane;

        public MainPane() {
            setLayout(new BorderLayout());

            cardLayout = new CardLayout();
            backgroundPane = new BackgroundPane();
            backgroundPane.setLayout(cardLayout);
            add(backgroundPane);

            backgroundPane.add(new MenuPane(this), Navigatable.View.MENU.name());
            JLabel label = new JLabel("This is the content");
            label.setHorizontalAlignment(JLabel.CENTER);
            backgroundPane.add(label, Navigatable.View.CONTENT.name());
        }

        @Override
        public void show(View view) {
            cardLayout.show(backgroundPane, view.name());
        }
    }

    public class MenuPane extends JPanel {
        public MenuPane(Navigatable navigatable) {
            setOpaque(false);
            setLayout(new GridBagLayout());
            setBorder(new EmptyBorder(32, 32, 32, 32));

            JButton btn = new JButton("Show me the content");
            add(btn);

            btn.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    navigatable.show(Navigatable.View.CONTENT);
                }
            });
        }       
    }

    public class BackgroundPane extends JPanel {

        private BufferedImage bgImage;

        public BackgroundPane() {
            try {
                bgImage = ImageIO.read(getClass().getResource("/images/Mando01-50.png"));
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }

        @Override
        public Dimension getPreferredSize() {
            if (bgImage != null) {
                return new Dimension(bgImage.getWidth(), bgImage.getHeight());
            }
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            if (bgImage == null) {
                return;
            }
            int x = (getWidth() - bgImage.getWidth()) / 2;
            int y = (getHeight() - bgImage.getHeight()) / 2;
            g.drawImage(bgImage, x, y, this);
        }
    }
}