CJV_1——ImageViewer via swing

package ImageViewer;

import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;

import javax.swing.ImageIcon;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;

public class ImageViewer {

	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable(){

			@Override
			public void run() {
				JFrame frame = new ImageViewerFrame();
				frame.setTitle("ImageViewer");
				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
				frame.setVisible(true);
				
			}
			
		});

	}

}
class ImageViewerFrame extends JFrame{
	/**
	 * 
	 */
	private static final long serialVersionUID = -4785279480839401296L;
	private JLabel label;
	private JFileChooser chooser;
	private static final int default_width = 300;
	private static final int default_height = 400;
	public ImageViewerFrame(){
		this.setSize(default_width, default_height);
		
		label = new JLabel();
		this.add(label);
		
		chooser = new JFileChooser();
		chooser.setCurrentDirectory(new File("."));
		
		JMenuBar menuBar = new JMenuBar();
		this.setJMenuBar(menuBar);
		
		JMenu menu = new JMenu("File");
		menuBar.add(menu);
		
		JMenuItem openItem = new JMenuItem("Open");
		menu.add(openItem);
		
		openItem.addActionListener(new ActionListener(){

			@Override
			public void actionPerformed(ActionEvent event) {
				int result = chooser.showOpenDialog(null);
				
				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(new ActionListener(){

			@Override
			public void actionPerformed(ActionEvent event) {
				System.exit(0);
				
			}
			
		});
	}
	
}

此段代碼在書中39頁，倘若我個人沒有之前的入門經歷，看這大段還是蠻被打擊的。