Java 实现简易图片查看器

import javax.swing.*;
import java.awt.*;
import java.io.File;

public class ImageViewer {
    public static void main(String[] args) {
        EventQueue.invokeLater(()->{
            JFrame frame = new ImageViewerFrame();
            frame.setTitle("ImageViewer");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setVisible(true);
        });
    }
}

class ImageViewerFrame extends JFrame{
    private JLabel label;
    private JFileChooser chooser;
    private static final int DEFAULT_WIDTH = 300;
    private static final int DEFAULT_HEIGHT = 400;

    public ImageViewerFrame(){
        setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT);

        // use a label to display the images
        label = new JLabel();
        add(label);

        // set up the file chooser
        chooser = new JFileChooser();
        chooser.setCurrentDirectory(new File("."));

        // set up the menu bar
        JMenuBar menuBar = new JMenuBar();
        setJMenuBar(menuBar);

        JMenu menu = new JMenu("File");
        menuBar.add(menu);

        JMenuItem openItem = new JMenuItem("Open");
        menu.add(openItem);
        openItem.addActionListener(event->{
            // show file chooser dialog
            int result = chooser.showOpenDialog(null);

            // if file selected, set it as icon of the label
            if (result == JFileChooser.APPROVE_OPTION){
                String name = chooser.getSelectedFile().getPath();
                label.setIcon(new ImageIcon(name));
            }
        });

        JMenuItem exitItem = new JMenuItem("Exit");
        menu.add(exitItem);
        exitItem.addActionListener(e -> System.exit(0));
    }
}