第一个Java程序，简单的打开图片并显示在面板上

代码如下：
 1 import java.awt.Component;
 2 import java.awt.EventQueue;
 3 import java.awt.Graphics;
 4 import java.awt.event.*;
 5 import java.io.*;
 6 import javax.swing.*;
 7 
 8 public class HelloWorld {
 9 
10     /**
11      * @param args
12      */
13     public static void main(String[] args) {
14         // TODO Auto-generated method stub
15         EventQueue.invokeLater(new Runnable() {
16             
17             @Override
18             public void run() {
19                 // TODO Auto-generated method stub
20                 JFrame frame = new ImageViewerFrame();
21                 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
22                 frame.setVisible(true);
23             }
24         });
25     }
26 }
27 
28 class ImageViewerFrame extends JFrame{
29     public ImageViewerFrame(){
30         setTitle("ImageViewer");
31         setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
32         label = new JLabel();
33         add(label);
34         chooser = new JFileChooser();
35         chooser.setCurrentDirectory(new File("."));
36         JMenuBar menubar = new JMenuBar();
37         setJMenuBar(menubar);
38         JMenu menu = new JMenu("File");
39         menubar.add(menu);
40         JMenuItem openItem = new JMenuItem("Open");
41         menu.add(openItem);
42         JMenuItem exitItem = new JMenuItem("Close");
43         menu.add(exitItem);
44         openItem.addActionListener(new ActionListener() {
45             
46             @Override
47             public void actionPerformed(ActionEvent arg0) {
48                 // TODO Auto-generated method stub
49                 int result = chooser.showOpenDialog(null);
50                 if(result == JFileChooser.APPROVE_OPTION){
51                     String name = chooser.getSelectedFile().getPath();
52                     label.setIcon(new ImageIcon(name));
53                 }
54             }
55         });
56         exitItem.addActionListener(new ActionListener() {
57             
58             @Override
59             public void actionPerformed(ActionEvent arg0) {
60                 // TODO Auto-generated method stub
61                 System.exit(0);
62             }
63         });
64     }
65     private JLabel label;
66     private JFileChooser chooser;
67     private static final int DEFAULT_WIDTH = 300;
68     private static final int DEFAULT_HEIGHT = 400;
69 }
显示效果如下：