How to show pictures in jFrame, using java2d?

问题

I'm new on working with Java and Netbeans. In many others languages, it's a simple stuff to do. But after broke my brain thinking, I couldn't. My doubt is simple to explain. How can I show bitmaps (stored on Hard Drive) in runtime, in a commom JFrame, using java2D? What I need to edit, and or create? Is it simple to do?

Thanks in advance...

回答1:

The basic process is use Graphics#drawImage to render an image you have previously loaded.

There are a number of things you need in order to achieve this...

• An image to paint
• A surface to paint on

Luckily, both these are relatively easy to achieve in Swing

• See ImageIO for reading images, Reading/Loading an Image
• See Performing Custom Painting for more details about how to perform painting in Swing...

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class ShowMyImage {

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

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

                ImagePane pane = new ImagePane();
                try {
                    pane.setImg(ImageIO.read(new File("C:\\hold\\thumbnails\\_MTCGAC__Pulling_Cords_by_Dispozition.png")));
                } catch (IOException ex) {
                    ex.printStackTrace();
                }

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

    public class ImagePane extends JPanel {

        private BufferedImage img;

        public ImagePane() {
        }

        public void setImg(BufferedImage value) {
            if (img != value) {
                img = value;
                repaint();
            }
        }

        public BufferedImage getImg() {
            return img;
        }

        @Override
        public Dimension getPreferredSize() {
            BufferedImage img = getImg();
            return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            BufferedImage img = getImg();
            if (img != null) {
                int x = (getWidth() - img.getWidth()) / 2;
                int y = (getHeight()- img.getHeight()) / 2;

                g2d.drawImage(img, x, y, this);
            }
            g2d.dispose();
        }
    }
}

回答2:

You need, as was told below to extend JPanel class and override paintComponent method in it.

public class DrawImageClass extends JPanel {
    private static final long serialVersionUID = 1L;
    private Image image;
    public DrawImageClass(Image image) throws HeadlessException {
        super();
        this.image = image;
    }

    @Override
    protected void paintComponent(Graphics g) {
        Graphics2D g2d = (Graphics2D)g;
        g2d.drawImage(image, null, null);
    }
}

And then create JFrame and add this class to it.

public class App {
    private static final int WIDTH=480, HEIGHT = 640;
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setSize(new Dimension(HEIGHT, WIDTH));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        try {
            DrawImageClass panel = new DrawImageClass(ImageIO.read(new File(App.class.getResource("/1.png").getPath())));
            panel.setPreferredSize(new Dimension(HEIGHT, WIDTH));
            frame.add(panel);
            frame.setVisible(true);
        } catch (Exception e) {
            System.out.println("wrong path or smth other");
        }  
    }
}

Example for picture which is in resource folder in project

回答3:

You can do this with the basic AWT package in java. You will need to extend the JFrame class and override its paintComponent method to display an image there. i.e.

public class MyFrame extends JFrame {
    private java.awt.Image bitmap = ImageIO.read(new File("myBitmap.bmp"));

    @Override
    public void paintComponent(java.awt.Graphics graphics) {
        int x = 0;
        int y = 0;
        int w = bitmap.getWidth(null);
        int h = bitmap.getHeight(null);
        graphics.drawImage(bitmap, x, y, w, h, this);
    }
}

You can simply instantiate it then

MyFrame myFrame = new MyFrame();
myFrame.setPreferredSize(new Dimension(100, 100));
myFrame.setVisible(true);

This is a basic example of course.

来源：https://stackoverflow.com/questions/17410168/how-to-show-pictures-in-jframe-using-java2d