我正在尝试添加JFrame背景图像，但它并未在Java中显示

Question

我正在尝试将背景图像添加到JFrame。

我尝试了所有可能的解决方案，但是它不起作用，我要做的就是将背景图像添加到JFrame，然后在其中打印形状，就像在我的代码中看到的那样。

有人可以帮我修复它吗？

public class Triangle {
    Oval o;

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

    public Triangle() {
        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 TestPane());
                frame.setSize(400, 400);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {
        private Polygon poly;

        {
            BufferedImage img = null;
            try {
                img = ImageIO.read(new File("apple.PNG"));
            } catch (IOException e) {
                e.printStackTrace();
            }
            Image dimg = img.getScaledInstance(800, 508, Image.SCALE_SMOOTH);
            ImageIcon imageIcon = new ImageIcon(dimg);
            setContentPane(new JLabel(imageIcon));

            poly = new Polygon(
                    new int[] { 110, 150, 50 },
                    new int[] { 200, 0, 0 },
                    3);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(400, 400);
        }

        private void setContentPane(JLabel jLabel) {
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2 = (Graphics2D) g;
            g2.setColor(Color.blue);
            g2.fill(poly);
            g2.setColor(Color.red);
            g2.fillRect(0, 0, 25, 75);
            g2.setColor(Color.green);
            g2.fillOval(200, 100, 100, 50);
            g2.setColor(Color.green);
            g2.fillOval(300, 300, 250, 250);
        }
    }
}

Answer 1

尝试一下。对我来说很好。

package model;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Polygon;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;

public class Triangle {

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

    public Triangle() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.setSize(400, 400);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {
        private Polygon poly;

        {
            poly = new Polygon(
                    new int[]{110, 150, 50},
                    new int[]{200, 0, 0},
                    3);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(400, 400);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            try {
                BufferedImage img = ImageIO.read(new File("apple.PNG"));
                Image dimg = img.getScaledInstance(800, 508, Image.SCALE_SMOOTH);
                g.drawImage(dimg, 0, 0, this.getWidth(), this.getHeight(), null);
            } catch (IOException e) {
                e.printStackTrace();
            }

            Graphics2D g2 = (Graphics2D) g;
            g2.setColor(Color.blue);
            g2.fill(poly);
            g2.setColor(Color.red);
            g2.fillRect(0, 0, 25, 75);
            g2.setColor(Color.green);
            g2.fillOval(200, 100, 100, 50);
            g2.setColor(Color.green);
            g2.fillOval(300, 300, 250, 250);
        }
    }
}